Shining a Light on Cancer: How Photodynamic Therapy Lighting is Revolutionizing Cancer Treatment

Have you ever stopped to think about the power of light? From spatial illumination to effective skincare, light has a wide range of applications in our daily lives.

However, one of the most powerful applications of light is for it be harnessed as a weapon in the fight against cancer. Photodynamic therapy, or PDT, is a groundbreaking medical procedure that harnesses the power of light to treat a variety of cancerous and precancerous conditions.

IN THIS NEWSLETTER:

• What is Photodynamic Therapy (PDT)?

• History of Photodynamic Therapy

• Role of Lighting and the respective PS Activation Wavelengths

• Drawbacks of Photodynamic Therapy

• What’s next for Photodynamic Therapy?

• Lighting Equipment Manufacturers

• Sources

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WHAT IS PHOTODYNAMIC THERAPY?

• Photodynamic therapy (PDT) is a promising treatment modality for cancer and other diseases, and the selection of the appropriate photosensitizer (PS) and light wavelength is critical for optimizing treatment outcomes.

• The wavelength of light used for activation of the PS can determine the depth of tissue penetration, with longer wavelengths (such as red light) penetrating deeper into tissues than shorter wavelengths (such as blue light). By choosing the appropriate PS and light wavelength, PDT can be used to selectively target cancer cells while sparing normal tissue.

Essentially, there are four steps involved in photodynamic therapy-

• The patient is giving a photosensitive drug (called photosensitizer or photosensitizing agent).

• After consumption, the drug get absorbed by the cancer cells.

• Cancer cells that have absorbed the photosensitizer are then exposed to light using either a laser or LEDs in an endogenous or exogenous manner.

• The light helps activate the photosensitizer to produce of form of oxygen that damages the cell structure and destroys the cancerous and precancerous cells.

HISTORY OF PHOTODYNAMIC THERAPY (PDT)

ANCIENT PRACTICES

• Utilization of sunlight as a healing and therapeutic agent isn’t anything new and found its place during the ancient times within the Greek, Egyptian and Indian civilizations.

• Egyptians associated colors with Gods, worshipped the sunlight and believed in shining the rays of light through colored crystals to penetrate the body and act as a treatment for a range of ailments.

• They were believed to be one of the pioneers of what we call, CHROMATHERAPY.

HOW DID PHOTODYNAMIC THERAPY (PDT) COME ABOUT?

• Like most discoveries, you can bet every dollar you have on the fact that this one was an accident as well.

• In the early 1900s, a medical student Oscar Raab was studying the interaction of fluorescent dyes on infusoria (minute freshwater life forms) and found that intense light applied to the dye resulted in rapid destruction of these microorganisms.

• Raab’s professors, Jesionek and von Tappeiner coined the term "photodynamic effect" and conducted the groundbreaking research on the use of photosensitizing agents and light to kill cells.

• This work also helped to elucidate the underlying mechanisms of the photodynamic effect, including the generation of reactive oxygen species and the damage caused to cellular structures by these species.

• However, despite descriptions of this light-mediated therapy in ancient texts and the discovery of photodynamic therapy, the landmark paper in 1978 in Cancer Research by Dougherty and his colleagues at the Roswell Park Cancer Institute remains rightly viewed as the starting point for clinical PDT in modern medicine.

ROLE OF LIGHTING AND THE RESPECTIVE PS ACTIVATION WAVELENGTHS

• The choice of photosensitizer and light wavelength will depend on the specific condition being treated, the depth and location of the target tissue, and other factors. The goal is to choose a combination of photosensitizer and light that will maximize the selectivity of the treatment, targeting abnormal cells while sparing normal tissue.

Below is a table summarizing the widely used photosensitizers, year of FDA approval, cancer treatments they are used for and range of light wavelengths used for their activation.

This in no way is an exhaustive list of photosensitizers. What really blows my mind is the number of cancer treatments listed under the indication column that utilize photodynamic therapy and underscore the importance of light as a resource in combating various forms of cancer.

DRAWBACKS OF PHOTODYNAMIC THERAPY

Damage to normal cells is limited but photodynamic therapy can still cause burns, swelling, pain, and scarring in the treatment area. Other side effects may occur depending on the area that is treated, including:

• Cough

• Trouble Swallowing

• Stomach Pain

• Painful Breathing

• Shortness of Breath

• Skin problems, such as redness, stinging, swelling, or itching

A type of photosensitizer called porfimer sodium makes the skin and eyes sensitive to light for about 6 weeks. During this time, you should avoid direct sunlight and bright indoor light.

However, it is important to note that side effects do typicall improve once the treatment is over.

WHAT’S NEXT FOR PHOTODYNAMIC THERAPY?

• Scientists and medical professionals are actively exploring ways to broaden the reach of photodynamic therapy (PDT) to treat a wider range of cancers.

• Innovative advances in photodynamic therapy (PDT) have led to the development of a new treatment approach called photoimmunotherapy, or PIT.

• PIT involves combining a photosensitizer with an immune protein that delivers the photosensitizer to cancer cells. Upon light activation, the photosensitizer selectively targets and destroys cancer cells, while also triggering an immune response that further targets cancer cells.

• Additional research is dedicated to the discovery of more advanced photosensitizers that offer improved efficacy and precision in targeting cancer cells.

• Efforts are also focused on identifying photosensitizers that can be triggered by light with greater tissue penetration, allowing for the treatment of larger or deeper tumors and with an area of investigation dedicated to potentially reducing their side effects.

LIGHTING EQUIPMENT MANUFACTURERS

• SPIE

• Modulight

• Novanta Photonics

• Omicron Laserage

• Illumacell

SOURCES

• NATIONAL CANCER INSTITUTE

• SCIENCEDIRECT

• AMERICAN CANCER SOCIETY

• NATIONAL LIBRARY OF MEDICINE

• CANADIAN CANCER SOCIETY

• WIKIPEDIA

• HEALTHLINE

• WILEY ONLINE LIBRARY

• LIPPINCOTT, WILLIAMS AND WILKINS

• ONCOLOGY TIMES

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