Does red light therapy stimulate tumor growth despite research suggesting it does not?

From the Guidelines

Red light therapy does not stimulate tumor growth, and its use can be considered safe in the context of cancer treatment, as long as it is discussed and approved by a medical professional. The evidence from the provided studies 1 suggests that red light therapy, particularly in the context of photodynamic therapy (PDT), has been effectively used to treat various skin conditions, including basal cell carcinoma (BCC) and cutaneous T-cell lymphoma, without promoting tumor growth. In fact, the studies demonstrate high response rates and sustained clearance of lesions with the use of red light therapy.

Key Findings

• A study published in the British Journal of Dermatology in 2008 1 reported an overall cure rate of 79% for superficial and nodular BCCs treated with methyl ester of ALA (MAL)-PDT, with a good or excellent cosmetic response in 98% of patients.
• The same study found that fractionation of light may enhance the efficacy of topical PDT in BCC, with a significantly higher response rate of 97% achieved with fractionated PDT compared to single illumination.
• Another study published in the British Journal of Dermatology in 2002 1 demonstrated the effectiveness of topical ALA-PDT in treating Bowen's disease, with a weighted complete clearance rate of 86% and a recurrence rate ranging from 0 to 40%.

Recommendations

• Red light therapy can be considered a safe and effective treatment option for certain skin conditions, including BCC and cutaneous T-cell lymphoma, under the guidance of a medical professional.
• Patients with a history of cancer or active tumors should consult with their oncologist before starting any red light therapy regimen to ensure it does not interfere with their primary cancer treatment.
• Typical red light therapy sessions can last 10-20 minutes, 3-5 times per week, using devices with wavelengths between 630-660 nm (red) or 810-850 nm (near-infrared), following manufacturer guidelines and healthcare provider recommendations.

From the Research

Tumor Growth and Red Light Therapy

• The study published in 2012 2 investigated the effects of low-level light therapy (LLLT) on tumor growth in a mouse model of nonmelanoma skin cancer, and found no measurable effect of LLLT on tumor growth.
• A 2021 study 3 evaluated the effects of a single red light-emitting diode (LED) irradiation on breast cancer-bearing mice, and observed that a single irradiation does not increase tumor volume.
• Another study published in 2021 4 discussed the clinical applications of low-level light therapy, including its use for skin rejuvenation, acne vulgaris, wound healing, and androgenic alopecia, but did not specifically address its effects on tumor growth.

Safety of Red Light Therapy in Cancer Patients

• A systematic review published in 2019 5 analyzed the safety of photobiomodulation therapy (PBMT) for the management of cancer-related toxicities, and found that the use of PBMT does not lead to tumor safety issues.
• A 2022 study 6 investigated the efficacy of red light phototherapy in preclinical models of melanoma, and found that red light phototherapy inhibits melanoma proliferation and alters tumor microenvironments.

Effects of Red Light Therapy on Tumor Growth

• The available evidence suggests that red light therapy does not stimulate tumor growth, and may even have inhibitory effects on certain types of cancer cells 2, 3, 6.
• However, further research is needed to fully understand the effects of red light therapy on tumor growth and to determine its potential as a therapeutic agent for cancer treatment.