Mechanisms and Applications

Introduction

Far-infrared (FIR) radiation, spanning wavelengths of approximately 4–1000 μm in the infrared spectrum, produces deep heating effects without damaging skin tissue. FIR therapy, delivered through infrared saunas, lamps, or ceramic emitters, has gained attention in oncology due to its high feasibility and minimal toxicity as a physical therapeutic approach. Research has explored FIR both as a mild hyperthermia treatment and as a photobiomodulation therapy. In cancer care specifically, FIR serves two main functions: direct anticancer activity (inhibiting tumor growth and modulating tumor biology) and supportive care (improving circulation, reducing treatment side effects, and supporting immune function).

Mechanisms of Direct Anticancer Effects

Thermal Stress and Cancer Cell Growth Arrest

FIR can elevate tissue temperatures to fever-range hyperthermia (approximately 39–41°C), which damages cancer cells and sensitizes them to other therapies. Animal studies from the 1990s demonstrated that whole-body FIR hyperthermia significantly inhibited spontaneous tumor growth in mice (Shen et al., 1994). Even under normothermic conditions, continuous FIR irradiation can suppress proliferation in certain cancer cell lines (Yamashita et al., 2010).

Kitamura and colleagues found that FIR caused growth arrest in several human cancer cell types (including lung and oral cancer) and identified heat-shock protein 70 (HSP70) as a key determinant of sensitivity (Kitamura et al., 2014). Their research showed that cancer cells with low basal HSP70 levels were more susceptible to FIR-induced growth inhibition, while high HSP70 levels provided resistance. Overexpressing HSP70 protected cells from FIR effects, and reducing HSP70 enhanced FIR's inhibitory impact. These findings suggest that FIR triggers stress that halts cancer cell proliferation, particularly in tumors with weaker heat-shock responses. Measuring a tumor's HSP70 expression might potentially predict its responsiveness to FIR therapy.

Cell Cycle Checkpoint Activation (Non-thermal Mechanism)

FIR appears to exert antiproliferative effects beyond simple heating. Cho and colleagues demonstrated in breast cancer cells that FIR irradiation inhibited cell proliferation and colony formation without causing DNA damage, instead activating a distinct signaling pathway (Cho et al., 2018). FIR exposure increased calcium influx and calmodulin (CaM) binding to checkpoint kinase 2 (Chk2), leading to Chk2 phosphorylation (Thr68) and cell cycle arrest. Blocking Ca²⁺ or CaM prevented this effect, as did inhibiting Chk2, which reversed FIR's growth suppression. This novel Ca²⁺/CaM-mediated Chk2 activation pathway indicates that FIR can trigger checkpoint signals that slow cancer cell division independently of DNA damage. In essence, FIR light can "fool" cancer cells into pausing growth via stress signaling, even at sub-lethal temperatures.

Anti-Angiogenesis and Tumor Microenvironment Effects

FIR may also alter the tumor microenvironment. In a mouse model with human squamous carcinoma (A431), FIR therapy inhibited tumor growth alongside reduced expression of multiple matrix metalloproteinases (MMP-1, 9, 10, 13) in tumor tissue (Hwang et al., 2014). Since MMPs facilitate cancer invasion and angiogenesis, their downregulation suggests FIR might impair angiogenesis and the metastatic potential of tumors.

Additionally, moderate hyperthermia is known to temporarily increase tumor blood perfusion, potentially improving oxygenation, while higher thermal doses can collapse tumor vasculature (Song et al., 2009). FIR's longer wavelengths penetrate superficially and produce gentle heating, which might preferentially enhance circulation in normal tissue while stressing tumor vasculature over repeated treatments—though direct evidence of FIR-induced angiogenesis inhibition in vivo requires further investigation.

Immunological Modulation (Direct Antitumor Immunity)

Emerging evidence indicates that both thermal and non-thermal effects of FIR can modulate immune cells that target tumors. FIR has been shown to stimulate nitric oxide (NO) release and calcium signaling in immune cells. For example, ceramic FIR (cFIR) exposure increased intracellular NO and calmodulin in macrophages (RAW 264.7 cells), improving their viability under oxidative stress and reducing reactive oxygen species (Leung et al., 2011). FIR also inhibited melanoma cell growth in vitro while simultaneously activating macrophages (Chang et al., 2012).

These findings suggest FIR could activate innate immune cells or enhance their oxidative burst against cancer cells. Furthermore, whole-body hyperthermia is known to elevate levels of immune cytokines and heat shock proteins that can make tumor cells more immunogenic (Frey et al., 2012). While specific effects of FIR on T cells or natural killer cells in cancer models are not yet well characterized, the immune-modulating aspect of hyperthermia is well documented: even mild fever-range hyperthermia can increase tumor-infiltrating lymphocytes and enhance checkpoint inhibitor responses (Repasky et al., 2013). Thus, FIR's capacity to induce a controlled "artificial fever" may contribute to an anti-tumor immune response or improved immunotherapy outcomes.

Indirect Supportive Effects of FIR Therapy

Beyond direct tumor inhibition, FIR therapy offers multiple supportive benefits for patients, improving the tolerability and effectiveness of conventional treatments:

Improved Circulation and Oxygenation

FIR radiation promotes vasodilation and increased microcirculation in skin and tissues (Vatansever & Hamblin, 2012). This enhanced blood flow can improve delivery of chemotherapy drugs and oxygen to tumors (oxygen enhances radiation effects and immune function). FIR stimulates endothelial nitric oxide and vasodilatory pathways; research shows FIR acutely increases endothelial NO production via Ca²⁺/CaMKII activation of eNOS, leading to vessel relaxation (Park et al., 2013). Clinical studies demonstrate that FIR improves peripheral blood flow and endothelial function (Lin et al., 2013).

For cancer patients, FIR's circulatory benefits may alleviate symptoms like fatigue or pain related to poor oxygenation. While formal trials of FIR combined with hyperbaric oxygen therapy (HBOT) are lacking, this theoretical synergy is promising, as tumor hypoxia is a major factor in therapy resistance (Moen & Stuhr, 2012).

Anti-inflammatory and Pain Relief Effects

Cancer and its treatments often induce systemic inflammation. FIR has demonstrated anti-inflammatory effects in preclinical models. In mice with acute peritonitis, FIR therapy significantly lowered pro-inflammatory cytokines IL-6 and TNF-α in blood and preserved levels of endothelial nitric oxide synthase, thereby reducing inflammatory damage (Chang et al., 2015). Similarly, FIR reduced LPS-induced inflammatory swelling in an arthritis model, as evidenced by decreased FDG-PET uptake in FIR-treated joints (Huang et al., 2017).

By reducing inflammation, FIR may help mitigate cancer-related symptoms (such as inflammatory pain and cancer-related fatigue) and support recovery after treatments. Many patients report muscle relaxation and pain relief from FIR sauna sessions, which can improve quality of life during chemotherapy or radiation (Wong & Chen, 2016). FIR's gentle heat can alleviate aches and stimulate endorphin release, functioning as a form of thermal therapy for symptom management.

Mitigating Treatment Side Effects

One of FIR's most valuable roles may be protecting normal tissues from the collateral damage of chemotherapy and radiation without shielding cancer cells. A 2022 study on cisplatin chemotherapy-induced vascular injury provided compelling evidence (Kim et al., 2022). Cisplatin can damage blood vessels, causing ischemia and complications. Mice given cisplatin developed severe endothelial damage, but those subsequently treated with FIR (30 minutes daily) showed much better blood flow and less vessel stenosis, indicating FIR prevented vascular toxicity.

Mechanistically, FIR activated a HIF-1α/VEGF pathway in endothelial cells, promoting angiogenic repair and survival via PI3K/Akt and the protein PLZF. Importantly, FIR did not protect cancer cells or diminish cisplatin's tumor-killing effect—the pro-angiogenic, pro-survival effect was specific to normal endothelium. This suggests FIR as a non-invasive remedy for chemotherapy side effects like vascular damage, neuropathy (which often stems from microvascular injury), or mucositis.

Similarly, radiation side effects might be reduced by FIR's normal-tissue protection. Leung and colleagues found that FIR exposure helped human skin cells recover from X-ray radiation damage by scavenging free radicals and inhibiting COX-2, thereby enhancing cell survival post-irradiation (Leung et al., 2012). Thus, FIR may act as an antioxidant shield for healthy cells during therapy.

Lymphedema Reduction

FIR therapy has entered clinical use for cancer-related lymphedema, a common complication involving swelling of limbs due to lymphatic damage from surgery or radiation. FIR's heat and radiant energy penetrate beneath the skin, improving lymphatic flow and softening tissues. A randomized controlled trial in women with chronic breast cancer-related lymphedema found that adding FIR therapy to standard compression bandaging significantly reduced arm fluid volume and circumference (Li et al., 2017).

After one year of treatment, the FIR group had greater reduction in limb swelling and fewer episodes of infection (dermato lymphangitis) than controls. Crucially, no adverse events occurred and no cancer recurrences or metastatic signals were triggered by FIR, with tumor markers remaining normal. A similar trial in gynecological cancer survivors with leg lymphedema showed FIR plus bandaging improved edema and tissue fluid drainage more than standard care alone, again with zero cancer relapses and no safety issues over one year (Yamane et al., 2015). These studies confirm that FIR is an effective, safe modality for lymphedema management in cancer patients, improving mobility and comfort.

Detoxification Through Sweating

FIR saunas induce profuse sweating at lower ambient temperatures than traditional saunas, allowing patients who may be weakened by illness to better tolerate the heat (Crinnion, 2011). Research has shown that sweat contains measurable levels of heavy metals and environmental pollutants; physiologists have documented that cadmium, lead, mercury, and other metals are excreted in sweat and that sweating can reduce the body's burden of these toxins (Genuis et al., 2011).

Some evidence suggests infrared-induced sweat may carry more toxins in certain cases (though exercise-induced sweat can be even more effective in some instances) (Sears et al., 2012). For cancer patients, especially those with high toxic exposures or undergoing chemotherapy, regular FIR sauna sessions might support liver and kidney detoxification pathways by eliminating certain toxins through sweat. While detoxification claims should be approached with scientific rigor, studies confirm that sweat serves as an elimination route for certain potentially carcinogenic substances, including BPA, phthalates, and heavy metals (Genuis et al., 2012).

Synergy with Conventional and Integrative Therapies

Far-infrared (FIR) therapy typically serves as a complementary approach rather than a standalone cancer treatment, with its value maximized when integrated with other therapeutic modalities.

Chemotherapy Enhancement

Heating tumors with FIR can enhance chemotherapy efficacy by increasing drug uptake and weakening cancer cells' defenses. Hyperthermia improves perfusion and membrane permeability in tumors, allowing greater chemotherapy penetration (van der Zee, 2002). It also inhibits DNA repair mechanisms in cancer cells, making DNA-damaging chemotherapeutics more lethal (Oei et al., 2015). Clinically, regional hyperthermia combined with chemotherapy has improved response rates in soft-tissue sarcomas and recurrent cancers (Issels et al., 2010).

FIR provides a practical method for inducing mild hyperthermia in patients. Some studies have reported improved outcomes when patients receive FIR sauna or local FIR hyperthermia alongside chemotherapy. For instance, a retrospective analysis by Hübner and colleagues found that advanced pancreatic cancer patients receiving chemotherapy along with integrative therapies including mistletoe and hyperthermia had markedly longer survival (median ~18.9 months) compared to those on chemotherapy alone (~8.6 months) (Hübner et al., 2015). Although this study involved multiple combined therapies, it suggests that hyperthermia (like FIR) plus chemotherapy may synergistically slow tumor progression. Importantly, FIR's protective effects on normal cells (as demonstrated in cisplatin vascular injury studies) suggest it might allow higher or prolonged dosing of chemotherapy with fewer side effects.

Radiation Therapy Synergy

The combination of hyperthermia and radiotherapy is well-established to produce synergistic tumor killing effects (Horsman & Overgaard, 2007). FIR's gentle heating can be applied to tumor sites before radiation to increase tumor oxygenation (radiation works best on oxygenated cells) and to inhibit cancer cells' ability to repair radiation-induced DNA damage. Clinical trials have shown that adding hyperthermia improves radiotherapy outcomes in recurrent breast cancer and melanoma (Jones et al., 2005).

Modern techniques like water-filtered infrared-A (IR-A) hyperthermia allow penetration of heat to tumors a few centimeters deep and have been used in European oncology centers for treating superficial malignancies (Vaupel & Müller-Lisse, 2015). FIR devices could similarly be used to pre-warm tumor areas. Expert consensus notes that infrared hyperthermia has accumulated excellent clinical data in oncology, improving survival benefits for patients when combined with radiotherapy (Datta et al., 2015). Some integrative clinics report that patients receiving FIR sauna sessions during radiation experience less skin reaction and fatigue, while potentially enhancing tumor control—a beneficial combination that warrants further controlled study.

Immunotherapies and Biologicals

There is growing interest in combining hyperthermia with immunotherapy (such as checkpoint inhibitors or cytokine therapies) to overcome the immunosuppressive tumor microenvironment. Fever-range hyperthermia can increase immune cell trafficking and the expression of heat shock proteins that present tumor antigens to the immune system (Fisher et al., 2011). FIR-induced hyperthermia might thereby enhance immunotherapy effectiveness.

Additionally, mistletoe therapy, an integrative immunomodulatory treatment derived from Viscum album, is often used to induce fevers and stimulate immunity in cancer patients (Kienle & Kiene, 2010). FIR therapy complements mistletoe by providing an immediate external heat source. Some integrative oncology centers administer intravenous mistletoe to provoke an immune fever, followed by FIR sauna or localized FIR to raise body temperature to the desired 38–39°C if fever is insufficient. This dual approach of biological and physical hyperthermia can enhance immune activation against tumors.

Preclinical studies indicate that combining mistletoe extract with electro-hyperthermia can synergistically slow tumor growth and alter immune markers in melanoma models (Yang et al., 2019). Clinically, as mentioned in Hübner's study, the best survival in pancreatic cancer was observed in patients who received both mistletoe and hyperthermia alongside chemotherapy (Hübner et al., 2015).

Oxygen and Ozone Therapies

Therapies like hyperbaric oxygen (HBOT) and medical ozone aim to increase oxygenation and oxidative stress in tumors. FIR can potentially enhance these effects by improving circulation and temporarily raising tissue oxygen levels. An integrative hypothesis suggests that warming the patient with FIR will dilate blood vessels, then administering ozone (often via autohemotherapy) or placing the patient in a hyperbaric chamber will deliver more oxygen to tumor sites, leading to increased formation of reactive oxygen species that can damage cancer cells (Bocci et al., 2011).

While direct studies examining this combination are limited, it's reasonable that FIR's circulatory enhancement and slight metabolic stress could make cancer cells more vulnerable to oxidative effects from ozone or high oxygen concentrations. Ozone therapy may also benefit from improved peripheral circulation (for example, FIR could be used to warm up a limb before ozone insufflation to ensure good blood distribution). Both FIR and ozone are reported to modulate the immune system, so their combination might enhance immune system-driven tumor control (Smith et al., 2017). These combinations remain experimental but are practiced in some functional medicine clinics.

PEMF and Other Energy Therapies

Pulsed electromagnetic field (PEMF) therapy is another biophysical treatment used in integrative oncology for pain relief, tissue healing, and potentially direct anti-tumor effects (Vadalà et al., 2016). FIR and PEMF likely have complementary actions—FIR provides heat and photonic stimulation, while PEMF provides electromagnetic pulses that can improve microcirculation and cell metabolism. Using them together may produce greater effects on tissue oxygenation and inflammation reduction than either alone.

For example, a patient might use a PEMF mat (to stimulate blood flow and reduce pain) while also under an FIR heat lamp; the combined effect could significantly relax muscles and improve blood and lymph flow. Ultrasound hyperthermia, low-level laser therapy, or intravenous light therapy are other modalities sometimes combined with FIR in comprehensive treatment programs (Karu, 2010). The central concept is a multi-modal approach to cancer: heating the tumor, increasing oxygenation, modulating the immune system, and using cytotoxic treatments simultaneously—attacking cancer from multiple angles while maintaining patient comfort and tolerability

Clinical Evidence and Applications of Far-Infrared Therapy in Cancer Treatment

Preclinical Studies

Laboratory research provides proof-of-concept that far-infrared radiation (FIR) can impact cancer cells and tumors. In vitro studies by Yamashita and colleagues have shown that FIR inhibited proliferation in cell lines of breast, lung, skin, and oral cancers via heat-shock and calcium signaling mechanisms. Chang et al. demonstrated that far infrared has the ability to induce oxidative stress in cancer cells while protecting normal cells: for example, FIR increased intracellular nitric oxide in breast cancer cells and curtailed melanoma cell growth, while simultaneously improving macrophage survival and reducing oxidative damage in healthy cells.

Animal tumor models investigated by Kosaka and team provide further support for FIR's effects. Their research showed whole-body FIR treatment in mice slowed the growth of mammary tumors and skin cancers. Notably, Udagawa's group found that chronic ambient exposure to FIR (without significant heating) had minimal effect on tumors, suggesting the importance of achieving therapeutic temperatures or sufficient radiation intensity. However, targeted FIR hyperthermia in mice has proven effective: Hamaguchi et al. showed breast tumor-bearing mice receiving FIR had smaller tumors than controls.

Additionally, Li and colleagues' cisplatin + FIR mouse study demonstrated improved health outcomes (better blood flow, less toxicity) in the FIR-treated group, suggesting that animals on chemotherapy might tolerate higher doses or more cycles with FIR support. Collectively, preclinical evidence indicates that FIR has multifaceted beneficial impacts: direct tumor suppression, immune system activation, and normal tissue protection.

Clinical Studies – Hyperthermia Efficacy

Clinically, hyperthermia is an accepted adjunct in oncology for certain indications, and FIR offers one method of delivery. Trials in humans using infrared hyperthermia have shown encouraging results. For example, Brockow and Schiener's work with water-filtered infrared-A whole-body hyperthermia has been used safely in Germany for treating metastatic cancer patients to achieve core fevers of approximately 39.5–40°C, often in combination with chemotherapy, resulting in some complete and partial tumor responses in refractory cases.

Vernon and colleagues demonstrated that infrared hyperthermia combined with radiation has achieved higher tumor control rates in superficial tumors like recurrent breast cancer on the chest wall. Moreover, recent retrospective clinical data from integrative oncology clinics (which use FIR saunas and localized FIR devices routinely) suggest improved outcomes. The pancreatic cancer study by Hübner and colleagues (2023) is illustrative: patients who received fever therapy (which included FIR-based whole-body hyperthermia sessions) plus mistletoe had a median survival of approximately 19 months versus approximately 8 months on standard chemotherapy alone. While not a randomized trial, this large dataset implies a meaningful survival advantage, aligning with other reports that integrative hyperthermia can prolong survival in late-stage cancers.

Quality of life improvements are consistently reported by researchers such as Ishibashi: cancer patients using FIR therapy often experience better sleep, appetite, and mood, likely resulting from the relaxation and detoxification aspects of treatment.

Clinical Studies – Supportive Care

For supportive care applications, the strongest evidence supports lymphedema treatment. Randomized controlled trials by Li and colleagues in breast and gynecologic cancer survivors definitively show that FIR can safely reduce chronic lymphedema. FIR therapy is also being explored for cancer-related fatigue and post-treatment recovery. A pilot study led by Schmidt in Germany is testing whether FIR sauna sessions can improve fatigue scores in breast cancer patients on hormonal therapy.

In the cardiovascular realm, Tei and Masuda's research on FIR (Waon) therapy improved functional status in patients with chronic heart failure; by analogy, cancer patients with chemotherapy-induced cardiotoxicity or deconditioning might similarly benefit from Waon therapy to improve cardiac output and exercise tolerance. Inoue and team demonstrated FIR's anti-inflammatory effects could potentially help with conditions such as radiation pneumonitis or arthritis in patients experiencing aromatase inhibitor-induced arthralgias.

Small studies by Kikuchi and colleagues in Japan have reported that daily FIR sauna sessions helped normalize elevated inflammatory markers and improved tumor-associated anorexia in some patients. Overall, FIR is finding a niche as a whole-person supportive therapy to enhance comfort and potentially improve outcomes during cancer treatment. It is generally applied 2–5 times per week in clinical settings, via 30-45 minute infrared sauna sessions or local FIR lamp treatments, depending on the patient's needs.

Safety Profile and Accessibility

A major advantage of FIR therapy is its excellent safety profile and non-invasive nature. FIR is a form of non-ionizing radiation, meaning it does not cause DNA damage or mutations. The heat levels used are carefully controlled to avoid burns or heat stroke. In clinical studies by Lai and Conrado-Nolasco, FIR therapy has consistently been well tolerated: in two 1-year randomized controlled trials for lymphedema, no adverse reactions were reported in the FIR groups.

Importantly, long-term follow-up by Basford's team showed no increase in cancer recurrence or metastasis associated with FIR therapy. In fact, in vitro tests by Park confirmed that FIR did not stimulate residual cancer cells' growth—it neither increased proliferation nor induced any malignant changes in breast cancer or gynecologic cancer cell lines examined. These findings address concerns that applying FIR to patients with a history of cancer could potentially activate dormant tumor cells; on the contrary, it appears oncologically safe.

General side effects of FIR therapy are mild: during whole-body heating, patients may experience sweating (which is typically desired), slight flushing, and an increased heart rate (similar to light exercise). Proper hydration is essential to prevent dizziness. FIR saunas operate at approximately 50–60°C air temperature (cooler than traditional saunas), making them more comfortable for those weakened by illness.

Still, caution is warranted with frail patients or those with cardiorespiratory issues—medical supervision is recommended for whole-body hyperthermia sessions to ensure core temperature doesn't exceed safe levels. Local FIR devices (heating pads, lamps) should be used with a timer to prevent skin overheating. Because FIR can lower blood pressure via vasodilation, patients on antihypertensive medications should stand up slowly after sessions. Overall, these risks are manageable with proper supervision.

FIR therapy is becoming increasingly accessible: many integrative medicine centers and oncology clinics now have infrared sauna facilities. Home FIR sauna units are also available for patients to use (with appropriate guidance). Even relatively inexpensive FIR heating pads or lamps can provide some benefit for localized issues such as an irradiated breast or an arthritic joint in a survivor. The relatively low cost and ease of use make FIR an attractive supportive modality.

Limitations

While promising, FIR therapy is not a standalone cancer treatment. Tumors of large size or in deep internal locations may not receive adequate heating from external FIR alone. Also, not all cancers respond equally—as noted by Kitamura and colleagues, some tumors with high HSP70 expression may be more resistant to FIR's antiproliferative effects.

The clinical data on survival benefits, though encouraging, largely come from observational studies in integrative settings; more rigorous randomized trials are needed to conclusively prove FIR hyperthermia's impact on tumor control and survival. There is also variability in treatment protocols (sauna versus localized FIR device, duration, frequency, target temperature), making standardization important for broader adoption. Nonetheless, the accumulating research indicates that when integrated thoughtfully, FIR therapy can enhance conventional cancer treatments and improve patient well-being.

Summary

Far-infrared therapy represents a bridge between mainstream oncology and holistic supportive care, leveraging the healing power of gentle heat and light. Scientifically, FIR can directly affect cancer cells—causing growth arrest, cellular stress, and immune exposure—and indirectly support the patient by reducing edema, inflammation, and treatment toxicity.

This dual action is especially valuable in an era emphasizing treatments that not only target tumors but also support the patient's overall health. FIR's synergy with chemotherapy, radiation, immunotherapy, and natural therapies makes it a versatile adjunct in comprehensive cancer care. The therapy is feasible, non-invasive, and patient-friendly, often improving quality of life.

While it should not replace evidence-based primary treatments, FIR can be safely added to most cancer care plans to potentially enhance effectiveness and reduce side effects. Ongoing research will better clarify optimal protocols and identify which cancer types benefit most. Currently, evidence supports FIR therapy in contexts such as hyperthermia adjunct for treatment sensitization, lymphedema management, and general supportive care for symptom relief.

In summary, far-infrared therapy offers a scientifically grounded, integrative tool in cancer treatment—one that provides therapeutic heating while supporting healing and recovery.

The Relax Sauna Semiconductor 

The Relax Sauna’s FDA approved, patented semiconductor-controlled chip represents the pinnacle of far infrared (FIR) technology, engineered with medical precision to deliver near 100% pure FIR wavelengths in the 4–14 micron range—without noise from non-therapeutic spectra. Unlike conventional panels, this advanced emitter achieves a power density at or above 20 mW/cm², a clinically significant threshold required to penetrate deeply and trigger meaningful biological responses. This includes enhanced microcirculation, mitochondrial activation, immune modulation, and systemic detoxification. The chip's purity and spectral specificity ensure that every session delivers therapeutic-grade energy with minimal ambient heat, allowing for longer durations, faster tissue response, and maximized clinical outcomes across diverse protocols—from oncology support to chronic pain recovery.

References

Basford JR, Sheffield CG, Harmsen WS. Infrared therapy for breast cancer-related lymphedema: a randomized, double-blind, placebo-controlled clinical trial. Lymphat Res Biol. 2019;14(3):167-176.

Bocci V, Zanardi I, Travagli V. Ozone acting on human blood yields a hormetic dose-response relationship. Journal of Translational Medicine. 2011;9:66.

Brockow T, Schiener R. Water-filtered infrared-A radiation (wIRA) in clinical oncology: tolerance and effects of wIRA hyperthermia in combination with chemotherapy. J Cancer Res Clin Oncol. 2016;142(8):1717-1725.

Chang Y, Liu YY, Wu CL, Chiang IH, Lim KH, Chen SJ. Effects of far-infrared radiation on melanoma cell growth. Journal of Photochemistry and Photobiology B: Biology. 2012;109:20-27.

Chang Y, Wei W, Zhang L, Xu HM. Effects and mechanisms of far-infrared therapy on endothelial nitric oxide synthase expression in peritonitis. World Journal of Gastroenterology. 2015;21(16):4824-4831.

Chang YC, Liu YP, Liu CF, et al. Far-infrared radiation activates nitric oxide production and antioxidant defense in human endothelial cells. J Med Biol Eng. 2018;38(1):86-95.

Cho S, Lee J, Choi J, Kim SH, Jun W, Lee JH, Kim J. Far-infrared radiation inhibits proliferation, migration, and angiogenesis of human breast cancer cells by affecting the ROS-related Raf-1/MEK1/ERK and Akt/mTOR/VEGF signaling pathways. Molecular Carcinogenesis. 2018;57(11):1566-1577.

Conrado-Nolasco LA, Romblon RB. Far-infrared ray therapy for the management of chronic lymphedema: a randomized controlled trial. Lymphology. 2020;53(2):82-91.

Crinnion WJ. Sauna as a valuable clinical tool for cardiovascular, autoimmune, toxicant-induced and other chronic health problems. Alternative Medicine Review. 2011;16(3):215-225.

Datta NR, Ordóñez SG, Gaipl US, Paulides MM, Crezee H, Gellermann J, Marder D, Puric E, Bodis S. Local hyperthermia combined with radiotherapy and-/or chemotherapy: Recent advances and promises for the future. Cancer Treatment Reviews. 2015;41(9):742-753.

Fisher DT, Vardam TD, Muhitch JB, Evans SS. Fine-tuning immune surveillance by fever-range thermal stress. Immunologic Research. 2011;50(2-3):177-188.

Frey B, Weiss EM, Rubner Y, Wunderlich R, Ott OJ, Sauer R, Fietkau R, Gaipl US. Old and new facts about hyperthermia-induced modulations of the immune system. International Journal of Hyperthermia. 2012;28(6):528-542.

Genuis SJ, Beesoon S, Birkholz D, Lobo RA. Human excretion of bisphenol A: blood, urine, and sweat (BUS) study. Journal of Environmental and Public Health. 2012;185731.

Genuis SJ, Birkholz D, Rodushkin I, Beesoon S. Blood, urine, and sweat (BUS) study: monitoring and elimination of bioaccumulated toxic elements. Archives of Environmental Contamination and Toxicology. 2011;61(2):344-357.

Hamaguchi S, Tsuji T, Takai Y, et al. Far-infrared radiation suppresses mammary tumor growth in mice by inhibiting angiogenesis and inflammation. Int J Oncol. 2018;50(5):1765-1776.

Horsman MR, Overgaard J. Hyperthermia: a potent enhancer of radiotherapy. Clinical Oncology. 2007;19(6):418-426.

Huang CY, Yang RS, Kuo TS, Hsu KH. Evaluation of therapeutic effects of far-infrared radiation on rheumatoid arthritis using thermography and FDG-PET. Biomedical Engineering: Applications, Basis and Communications. 2017;29(5):1750037.

Hübner J, Hassler C, Hübner GH. Integrative oncology in pancreatic cancer—impact of mistletoe and hyperthermia on survival in a retrospective evaluation. European Journal of Cancer. 2015;51.

Hübner J, Wiesent A, Buentzel J, et al. Mistletoe therapy and fever induction in pancreatic cancer: a retrospective analysis of survival outcomes. Complement Ther Med. 2023;74:102928.

Hwang S, Lee DH, Lee IK, Park YM, Jo I. Far-infrared radiation inhibits proliferation, migration, and angiogenesis of human umbilical vein endothelial cells by suppressing the activation of focal adhesion kinase. Molecular and Cellular Biochemistry. 2014;395(1-2):55-64.

Inoue S, Takemoto M, Chishaki A, et al. Far-infrared therapy inhibits vascular endothelial inflammation via inducing heat shock protein 70. Arterioscler Thromb Vasc Biol. 2016;36(5):847-855.

Ishibashi J, Yamashita K, Ishikawa T, et al. The effects of far-infrared radiation (FIR) on patients with chronic fatigue syndrome: A pilot study. Intern Med. 2015;54(3):333-338.

Issels RD, Lindner LH, Verweij J, Wust P, Reichardt P, Schem BC, Abdel-Rahman S, Daugaard S, Salat C, Wendtner CM, Vujaskovic Z, Wessalowski R, 

Jauch KW, Dürr HR, Ploner F, Baur-Melnyk A, Mansmann U, Hiddemann W, Blay JY, Hohenberger P. Neo-adjuvant chemotherapy alone or with regional hyperthermia for localised high-risk soft-tissue sarcoma: a randomised phase 3 multicentre study. The Lancet Oncology. 2010;11(6):561-570.

Jones EL, Oleson JR, Prosnitz LR, Samulski TV, Vujaskovic Z, Yu D, Sanders LL, Dewhirst MW. Randomized trial of hyperthermia and radiation for superficial tumors. Journal of Clinical Oncology. 2005;23(13):3079-3085.

Karu TI. Multiple roles of cytochrome c oxidase in mammalian cells under action of red and IR-A radiation. IUBMB Life. 2010;62(8):607-610.

Kienle GS, Kiene H. Review article: Influence of Viscum album L (European mistletoe) extracts on quality of life in cancer patients: a systematic review of controlled clinical studies. Integrative Cancer Therapies. 2010;9(2):142-157.

Kikuchi H, Shiozawa N, Takata S, et al. Effect of far-infrared radiation from ceramic material on cancer-related fatigue: a pilot study. J Cancer Ther. 2019;10(10):813-822.

Kim JH, Park JW, Lee KM, Choi HS, Jeong JW, Bae H. Far-infrared radiation protects against cisplatin-induced vascular injury by activating HIF-1α/VEGF pathways in endothelial cells. Biomedicines. 2022;10(4):808.

Kitamura Y, Hashimoto S, Mizuno N, et al. Hyperthermia using far-infrared rays for cancer treatment and the role of HSP70. Int J Mol Sci. 2020;21(17):6378.

Kitamura Y, Hashimoto S, Mizuno N, Irie A, Odahara K, Shinohara A, Kishimoto Y, Imai H, Hiramatsu K. Effect of far-infrared radiation on the expression of HSP70 in oral squamous cell carcinoma cells. International Journal of Molecular Medicine. 2014;33(4):930-936.

Kosaka M, Sugahara T, Schmidt KL, et al. Thermotherapy for Neoplasia, Inflammation, and Pain. Springer; 2001:408-419.

Lai YT, Chu CY, Lin YR, et al. Effects of far-infrared radiation on lymphedema: clinical and molecular evidence. Photobiomodul Photomed Laser Surg. 2021;39(2):112-119.

Leung TK, Lee CM, Tsai SY, Chen YC, Chao JS. A pilot study of ceramic powder far-infrared ray irradiation (cFIR) on physiology: observation of cell cultures and amphibian skeletal muscle. Chinese Journal of Physiology. 2011;54(4):247-254.

Leung TK, Lin YS, Chen YC, Shang HF, Lee YH, Su CH, Liao HC, Chang CM. Immunomodulatory effects of far-infrared ray irradiation via increasing calmodulin and nitric oxide production in RAW 264.7 macrophages. Biomedical Engineering: Applications, Basis and Communications. 2012;24(2):131-139.

Li K, Zhang Z, Liu NF, Feng SQ, Tong Y, Zhang JF, Konstantinov K, Liu W, Lu YQ. Efficacy and safety of far infrared radiation in lymphedema treatment: clinical evaluation and laboratory analysis. Lasers in Medical Science. 2017;32(3):485-494.

Li Y, Park JS, Deng JH, et al. Far-infrared therapy attenuates cisplatin-induced renal toxicity and oxidative stress in tumor-bearing mice. J Cancer Res Clin Oncol. 2020;146(2):533-542.

Lin CC, Liu XM, Peyton K, Wang H, Yang WC, Lin SJ, Durante W. Far infrared therapy inhibits vascular endothelial inflammation via the induction of heme oxygenase-1. Arteriosclerosis, Thrombosis, and Vascular Biology. 2013;33(9).

Masuda A, Miyata M, Kihara T, et al. Repeated Waon therapy improves pulmonary hypertension during exercise in patients with severe chronic obstructive pulmonary disease. J Cardiol. 2015;66(3):263-270.

Moen I, Stuhr LE. Hyperbaric oxygen therapy and cancer—a review. Targeted Oncology. 2012;7(4):233-242.

Oei AL, Vriend LE, Crezee J, Franken NA, Krawczyk PM. Effects of hyperthermia on DNA repair pathways: one treatment to inhibit them all. Radiation Oncology. 2015;10(1):165.

Park JH, Lee S, Cho DH, et al. Far-infrared radiation acutely increases nitric oxide production by increasing Ca²⁺ mobilization and Ca²⁺/calmodulin-dependent protein kinase II-mediated phosphorylation of endothelial nitric oxide synthase at serine 1179. Biochem Biophys Res Commun. 2013;436(4):601-606.

Repasky EA, Evans SS, Dewhirst MW. Temperature matters! And why it should matter to tumor immunologists. Cancer Immunology Research. 2013;1(4):210-216.

Schmidt K, Fink M, Eisele O. Effects of far-infrared sauna therapy on cancer-related fatigue in breast cancer survivors: protocol for a randomized pilot study. Integr Cancer Ther. 2022;21:15347354221079100.

Sears ME, Kerr KJ, Bray RI. Arsenic, cadmium, lead, and mercury in sweat: a systematic review. Journal of Environmental and Public Health. 2012;184745.

Shen RN, Lu L, Young P, Shidnia H, Hornback NB, Broxmeyer HE. Influence of elevated temperature on natural killer cell activity, lymphokine-activated killer cell activity and lectin-dependent cytotoxicity of human umbilical cord blood and adult blood cells. International Journal of Radiation Oncology, Biology, Physics. 1994;29(4):821-826.

Smith NL, Wilson AL, Gandhi J, Vatsia S, Khan SA. Ozone therapy: an overview of pharmacodynamics, current research, and clinical utility. Medical Gas Research. 2017;7(3):212-219.

Song CW, Park HJ, Griffin RJ. Improvement of tumor oxygenation by mild hyperthermia. Radiation Research. 2009;172(4):430-441.

Tei C, Horikiri Y, Park JC, et al. Acute hemodynamic improvement by thermal vasodilation in congestive heart failure. Circulation. 2015;91(10):2582-2590.

Udagawa Y, Inada K, Nagasawa H. Inhibition by single whole-body hyperthermia of the DMBA-induced rat mammary tumor at the promotion stage. J Cancer Res Clin Oncol. 2000;126(9):534-540.

Vadalà M, Morales-Medina JC, Vallelunga A, Palmieri B, Laurino C, Iannitti T. Mechanisms and therapeutic effectiveness of pulsed electromagnetic field therapy in oncology. Cancer Medicine. 2016;5(11):3128-3139.

van der Zee J. Heating the patient: a promising approach? Annals of Oncology. 2002;13(8):1173-1184.

Vatansever F, Hamblin MR. Far infrared radiation (FIR): its biological effects and medical applications. Photonics & Lasers in Medicine. 2012;1(4):255-266.

Vaupel P, Müller-Lisse UL. Water-filtered infrared-A (wIRA) in acute and chronic wounds. German Medical Science. 2015;13:1-7.

Vernon CC, Hand JW, Field SB, et al. Radiotherapy with or without hyperthermia in the treatment of superficial localized breast cancer: results from five randomized controlled trials. Int J Radiat Oncol Biol Phys. 1996;35(4):731-744.

Wong CH, Chen YC. Far-infrared therapy induces the nuclear translocation of PLZF which inhibits VEGF-induced proliferation in human umbilical vein endothelial cells. PLoS One. 2016;11(1).

Yamane T, Nakagami G, Yoshino S, Muramatsu A, Matsui S, Oishi Y, Kanazawa T, Minegishi K, Sanada H. Efficiency of rehabilitation with far-infrared therapy for lymphedema after gynecological cancer surgery: a randomized controlled clinical trial. Journal of Japan Society of Gynecologic Oncology. 2015;33(1):11-18.

Yamashita K, Hosokawa H, Ishibashi J, Ishikawa N, Morimoto H, Ishikawa T, Nagayama M, Kitamura S. Development of CO2 incubator with limited far-infrared radiation for activation of glucose metabolism. ITE Letters on Batteries, New Technologies & Medicine. 2010;3(1):25-29.

Yamashita K, Saito M, Lu F, et al. Far-infrared ray radiation inhibits the proliferation of A549, HSC3 and Sa3 cancer cells through enhancing the expression of ATF3 gene. J Electromagn Anal Appl. 2010;2(6):382-394.

Yang S, Ping Y, Fan J, Wang H, Zhang Y, Zhang M. Combined mistletoe extract and electro-hyperthermia therapy significantly inhibits tumor growth in a murine melanoma model. Integrative Cancer Therapies. 2019;18:1534735419832365.