Photobiomodulation and cancer: can red light help patients during chemotherapy and radiation therapy?

Can red light cure cancer?

It is a question we are hearing more and more frequently in the clinic.

Photobiomodulation using red and near-infrared light is generating growing interest among patients undergoing oncological treatments. Some have read that this technology stimulates the mitochondria, promotes cellular repair, or modulates inflammation. Others have even heard that it might destroy cancer cells.

But how much truth is there in all of this?

The answer requires distinguishing between two entirely different concepts: treating a cancer and helping a person better tolerate the consequences of their treatment.

Currently, there is insufficient clinical evidence to assert that conventional red LED photobiomodulation sessions destroy tumors, eliminate cancer cells, or cure cancer.

However, there is scientific research that does support its use in certain complications arising from oncological treatments.

In fact, photobiomodulation is already included in international recommendations for preventing some forms of oral mucositis, a particularly painful complication of chemotherapy and radiotherapy.

In this article we will analyze which benefits have been demonstrated, which are still under investigation, and what precautions we should take.

1. What exactly is photobiomodulation?

Photobiomodulation, known internationally as photobiomodulation therapy (PBM), is a non-invasive technique that uses specific wavelengths of visible and near-infrared light.

Wavelengths of approximately 600 to 1,100 nanometers are typically used, although the specific parameters depend on the indication and the device.

Unlike ultraviolet radiation or X-rays, these wavelengths are non-ionizing.

Light can interact with different cellular components and trigger biological responses related to:

• Energy metabolism.

• Mitochondrial signaling.

• The regulation of certain inflammatory pathways.

• The response to oxidative stress.

• Tissue repair processes.

• The modulation of certain pain-related signals.

One of the most studied mechanisms involves the interaction of specific wavelengths with components of the mitochondrial respiratory chain, particularly cytochrome c oxidase.

However, the mechanisms are complex and have not yet been fully elucidated.

It is important to understand that photobiomodulation does not act in the same way in all cells, tissues, or diseases.

The response depends on the wavelength, irradiance, delivered energy, duration, frequency of sessions, and the biological characteristics of the tissue.

Red light and mitochondria: how photobiomodulation works in our cells

2. Why is photobiomodulation of interest in oncology?

Cancer treatments have evolved extraordinarily over the past few decades.

Chemotherapy, radiotherapy, immunotherapy, and targeted therapies have made it possible to improve the prognosis of numerous malignant diseases.

However, these treatments can produce significant side effects.

Among them we find:

• Inflammation and ulceration of the mucous membranes.

• Skin lesions related to radiotherapy.

• Pain and sensory disturbances.

• Peripheral neuropathies.

• Edema and lymphedema.

• Tissue fibrosis.

• Swallowing disorders.

• Fatigue and deterioration of quality of life.

Some of these complications can interfere with eating, rest, mobility, and daily activities.

In certain cases, they may even compel the oncology team to temporarily modify the treatment.

For this reason, modern oncological medicine does not limit itself to fighting the tumor: it also seeks to prevent and alleviate the complications associated with treatment.

This set of interventions is known as oncological supportive care.

And it is precisely within this field that photobiomodulation presents its most interesting applications.

3. Oral mucositis: the application with the greatest scientific support

Oral mucositis is one of the most extensively studied complications of photobiomodulation in oncology.

It is characterized by inflammation and injury to the oral mucosa, which can cause:

• Severe pain.

• Oral ulcers.

• Difficulty eating.

• Problems drinking and swallowing.

• Speech impairment.

• Greater need for analgesia.

• Risk of infectious complications.

It can appear during certain chemotherapy treatments, head and neck radiotherapy, and following hematopoietic stem cell transplantation procedures.

What have studies shown?

Several clinical trials have observed that certain photobiomodulation protocols can reduce the occurrence or severity of oral mucositis.

The 2020 MASCC/ISOO recommendations include specific intraoral photobiomodulation protocols for preventing mucositis in certain clinical situations, including:

• Adults undergoing hematopoietic stem cell transplantation with high-intensity conditioning.

• Patients with head and neck cancer treated with radiotherapy.

• Patients with head and neck cancer treated with radiotherapy combined with chemotherapy.

These recommendations are based on precise protocols, with defined devices, doses, and application times.

It is one of the clearest demonstrations that photobiomodulation can have real utility in oncology without acting directly as an anticancer treatment.

It is worth noting that the intraoral protocols studied are not equivalent to standing in front of a full-body LED panel.

4. Radiodermatitis: can red light help irradiated skin?

Radiotherapy can produce skin reactions of varying severity.

Its manifestations include:

• Erythema.

• Dryness.

• Itching.

• Burning sensation.

• Desquamation.

• Pain.

• More significant skin lesions in certain patients.

Photobiomodulation has been investigated as a possible preventive or complementary intervention to reduce some of these reactions.

The results of various studies are promising, although significant methodological differences still exist.

In 2022, WALT published consensus recommendations to continue researching and applying specific protocols for certain radiotherapy-related complications.

However, for radiodermatitis there is still no universal protocol with the same strength of evidence as some oral mucositis indications.

Furthermore, it is essential to assess the irradiated area, the presence of tumour lesions, and the characteristics of the oncological treatment.

Photobiomodulation should not be used directly over a known tumoral area without specialist guidance and clinical justification.

5. Peripheral neuropathy caused by chemotherapy

Some antineoplastic medications can cause damage to the peripheral nerves.

This is what we know as chemotherapy-induced peripheral neuropathy.

It can present as:

• Tingling in the hands and feet.

• A burning sensation.

• Neuropathic pain.

• Loss of sensitivity.

• Balance disturbances.

• Difficulty performing fine movements.

Among the medications associated with this condition are certain taxanes, platinum compounds, and other neurotoxic agents.

What role could photobiomodulation play?

Research is ongoing into whether PBM can modulate inflammation, neuronal metabolism, and certain processes related to peripheral nerve recovery.

Preliminary studies and consensus technical recommendations exist to encourage further research.

However, the current evidence does not yet allow us to state that photobiomodulation reliably prevents or treats all neuropathies caused by chemotherapy.

Nor should it replace neurological evaluation or the therapeutic measures indicated by the oncology team.

Its potential role should be considered complementary and still subject to ongoing research.

6. Lymphedema after breast cancer

Lymphedema can appear after certain oncological surgeries or radiotherapy treatments.

It occurs when there is an alteration of lymphatic drainage, which promotes the accumulation of fluid in the tissues.

It can cause increased limb volume, a feeling of heaviness, functional limitation, and discomfort.

Photobiomodulation has been studied as a complementary treatment in patients with lymphedema, particularly following breast cancer.

Some studies have reported improvements in certain symptoms or functional measures.

However, the results are heterogeneous and do not justify replacing decongestive therapy, compression, therapeutic exercise, or specialized follow-up.

PBM may have a complementary role in selected patients, but more robust clinical trials are still needed.

7. Fibrosis and sequelae of radiotherapy

Radiotherapy can cause persistent changes in the tissues.

In some patients, hardening, loss of elasticity, discomfort, or functional limitations may develop.

Photobiomodulation is being investigated for its possible influence on inflammation, tissue remodeling, and certain processes related to fibrosis.

Although plausible biological hypotheses and preliminary results exist, there is still insufficient evidence to recommend it systematically as a treatment for all post-radiotherapy fibrosis.

Its application should be assessed according to the location, the time elapsed since treatment, and the current oncological status.

8. Cancer-related fatigue: a particularly important issue

Cancer-related fatigue is one of the most common and difficult symptoms to manage.

It is not simply a matter of feeling tired.

It can be a persistent sense of physical, mental, or emotional exhaustion that does not fully improve with rest.

Its causes may include the disease itself, inflammation, anaemia, sleep disorders, loss of muscle mass, and the side effects of treatments.

Can red light help?

There is scientific interest in studying photobiomodulation and its possible influence on energy metabolism, muscle function, and certain fatigue-related symptoms.

However, there is not yet sufficiently robust clinical evidence to assert that whole-body LED sessions consistently improve cancer-related fatigue.

It is an interesting line of research, but it should not be presented as a proven benefit.

Patients with significant fatigue need a medical evaluation to identify treatable causes and to access interventions of known efficacy, such as adapted exercise programmes, rehabilitation, nutritional support, and treatment of associated problems.

9. Does photobiomodulation help patients tolerate chemotherapy better?

The answer is that it may help manage certain complications, but it has not been demonstrated to broadly improve tolerance to all chemotherapy treatments.

This distinction is fundamental.

For example, if a patient is at risk of oral mucositis and receives a PBM protocol validated for their clinical situation, they may benefit from a reduction in that complication.

This can translate into less pain, fewer difficulties eating, and a better quality of life during treatment.

But it does not mean that red light neutralises the overall toxicity of chemotherapy.

Nor does it mean that it automatically protects the liver, kidneys, heart, or all healthy tissues.

There is insufficient evidence to recommend full-body LED sessions as a general measure to prevent all adverse effects of chemotherapy.

The application must be directed toward specific, measurable clinical objectives.

10. Can red light destroy cancer cells?

This is probably the most important misconception we need to clarify.

Online, one can find claims presenting red light as a technology capable of eliminating malignant cells.

However, it is essential to distinguish conventional photobiomodulation from other medical techniques that also use light.

Photobiomodulation and photodynamic therapy are not the same thing

Photodynamic therapy uses a photosensitizing agent and an appropriate light source to trigger reactions capable of producing cellular damage.

It is used in certain dermatological conditions and in specific oncological indications.

Conventional photobiomodulation, on the other hand, seeks to modify biological responses through light doses that are not aimed at destroying tissue.

Therefore, we must not confuse:

• Photodynamic therapy: can destroy cells through specific photochemical mechanisms.

• Photobiomodulation: seeks to modulate certain cellular and tissue functions.

The fact that both use light does not mean they have the same effects.

11. Is there a risk of stimulating cancer cells?

This question deserves a particularly careful answer.

Photobiomodulation can influence mechanisms related to cellular metabolism, proliferation, and intracellular signaling.

Some laboratory studies have observed increases in proliferation in certain tumor cell lines following specific exposures.

Other studies have observed inhibitory effects or an absence of relevant changes.

These differences may depend on the cell type, wavelength, dose, and experimental conditions.

What happens in real patients?

A systematic review published in Cancer Medicine in 2020 analyzed 67 studies:

• 43 in vitro studies.

• 15 animal studies.

• 9 clinical studies.

The experimental results were heterogeneous.

The available clinical studies did not identify a general increase in tumor progression or recurrence associated with the protocols studied.

However, this does not demonstrate that any device, dose, or modality of photobiomodulation is completely safe in all cancers.

The absence of an unfavorable signal in certain studies is not equivalent to an absolute guarantee of long-term safety.

12. What do international experts say?

The World Association for Photobiomodulation Therapy (WALT) published a position paper in 2022 dedicated to the use of PBM in complications arising from oncological treatments.

The consensus acknowledges the potential of this technique for various supportive care indications.

It also considers that PBM may be used in patients with cancer when there is an appropriate indication and clinical precautions are observed.

Nevertheless, experts advise against direct exposure of known tumours and emphasise the importance of individualised dosimetry.

The document also acknowledges that definitive data on all possible tumour-related effects and long-term safety are not yet available.

Therefore, the scientific position is not to prohibit all photobiomodulation for patients with cancer, but neither is it to indiscriminately authorise any exposure.

13. What is the difference between a localised treatment and a full-body LED session?

This difference is fundamental.

Many of the scientific studies on photobiomodulation in oncology use devices applied to specific areas.

For example:

• Oral mucosa.

• Irradiated skin.

• Certain regions affected by neuropathy.

• Areas with edema or functional impairments.

Researchers control the wavelength, power, delivered energy, treated surface area, and number of sessions.

Full-body LED devices expose much larger surface areas and can combine several wavelengths simultaneously.

Therefore, it is not scientifically correct to automatically transfer the results of an intraoral treatment to a full-body 20-minute exposure.

Safety and efficacy must be evaluated taking into account the specific device and protocol.

In patients with active cancer, this difference takes on particular relevance.

LED masks: real photobiomodulation or simply red light?

14. Can photobiomodulation be used during chemotherapy?

In certain situations, yes.

In fact, some mucositis prevention protocols are specifically designed for patients undergoing cancer treatments.

However, the decision depends on several factors:

• Type of cancer.

• Tumor location.

• Oncological treatment administered.

• Complication to be prevented or treated.

• General condition of the patient.

• Photosensitizing medications.

• The body area that will receive the light.

• Device parameters.

Treating oral mucositis using a validated protocol is not the same as performing a whole-body LED exposure in a patient with active metastatic disease.

In this latter context, the evidence remains insufficient to recommend the procedure on a routine basis.

15. What about after overcoming cancer?

Patients who have completed their oncological treatments may present persistent after-effects.

These include skin changes, fibrosis, muscle discomfort, edema, and neuropathies.

A prior history of cancer does not, in itself, constitute an absolute contraindication for all modalities of photobiomodulation.

Nevertheless, the type of tumor, its location, the time elapsed, the current status of the disease, and the treatment objective must all be taken into consideration.

In some patients, a localized application could be reasonable.

In others, it will be preferable to use better-established supportive treatments.

The assessment must be individualized.

16. Safety, contraindications, and informed consent

Photobiomodulation is generally well tolerated when applied correctly.

However, it may cause discomfort, heat, transient erythema, skin irritation, or problems arising from inadequate exposure.

Certain photosensitive conditions, medications, ocular problems, and other clinical circumstances must also be taken into account.

In patients with an oncological history, having an up-to-date medical record is especially important.

Before performing the procedure, ongoing treatments, disease status, and the areas that will be exposed must be known.

The informed consent must explain in a comprehensible way the expected benefits, the limitations of the evidence, and the existing uncertainties.

In patients with active cancer, coordination with the responsible oncologist is particularly important.

Patient consent does not replace medical assessment, nor does it turn an unvalidated procedure into a safe or effective treatment.

17. Which patients might benefit the most?

Selection should be based on the complication to be treated, not solely on the cancer diagnosis.

The indication with the strongest support is the prevention of oral mucositis in specific populations undergoing oncological treatments.

Other applications, such as radiodermatitis, neuropathy, lymphedema, or fibrosis, require individual assessment of the quality of the evidence and the availability of appropriate protocols.

Generalised fatigue, overall improvement of the immune system, or the prevention of tumour recurrence should not be presented as demonstrated benefits of full-body LED sessions.

Photobiomodulation can be an interesting complementary tool, but it is not a universal solution.

Summary: level of evidence for photobiomodulation in oncology

The MASCC/ISOO and WALT recommendations make it possible to distinguish between these indications, without treating them as equivalent in terms of level of evidence.

18. Frequently asked questions

Can I have red light sessions if I have cancer?

It depends on the clinical situation and the indication. Cancer does not constitute an absolute contraindication for all photobiomodulation, but full-body sessions in patients with active disease require particular caution and have not been validated in a general way.

Does red light destroy cancer cells?

There is insufficient clinical evidence to demonstrate that conventional red LED photobiomodulation sessions eliminate tumors or cure cancer.

Can photobiomodulation help during chemotherapy?

Yes, for certain complications and with specific protocols, particularly to prevent some forms of oral mucositis. It has not been shown to reduce all side effects of chemotherapy.

Can it improve neuropathy caused by chemotherapy?

This possibility is being investigated, but there is not yet sufficient evidence to recommend it as a standard treatment.

Does it help combat cancer-related fatigue?

It is a line of research, but it has not been conclusively demonstrated that whole-body LED sessions reduce oncological fatigue.

Can it increase tumor growth?

Experimental studies show variable results. Clinical studies of certain applications have not identified a general increase in recurrences, but they do not allow the safety of any exposure — or across all cancer types — to be guaranteed.

Can I receive photobiomodulation after overcoming cancer?

It may be possible following an individual assessment. Medical history, current situation, and the objective of the intervention must all be considered.

Do full-body LED sessions replace localized medical photobiomodulation?

No. The localized protocols used in oncological research have specific parameters, and their results cannot be automatically extrapolated to full-body devices.

19. The doctor's reflection

In medicine, we must maintain an open attitude toward new technologies, while also upholding constant scientific rigor.

Photobiomodulation represents an interesting field of research, especially within the realm of oncological supportive care.

Its usefulness in certain complications, such as oral mucositis, demonstrates that light can become a valuable therapeutic tool when used according to appropriate medical criteria.

But we must avoid two mistakes.

The first would be to reject any application of photobiomodulation simply because the patient has a history of cancer.

The second, equally important, would be to present red light as a treatment capable of destroying tumors or guaranteeing a faster recovery after chemotherapy.

The available evidence does not support these claims.

The goal of supportive care is to improve quality of life, relieve symptoms, and accompany the patient through a process that can be physically and emotionally difficult.

And when a technology demonstrates that it can contribute to that goal, it deserves to be studied and used responsibly.

Dr. Florian Vallecillo · El Doctor Explica · Clínica Valorian — Marbella