Photodynamic therapy

Killing cancer cells with high-intensity light energy




Photodynamic therapy uses non-toxic, herb-derived or semi-synthetic drugs to make cancer cells more vulnerable to a particular wavelength of light. The herbal compounds — such as curcumin, hypericin and especially chlorine e6 — therefore act as so-called photosensitizers or photosensitizing agents.


The photodynamic therapy involves injecting the photosensitizer into the bloodstream. Due to the increased uptake by malignant cells, the accumulation is rather specific and targeted to cancer cells. When the photosensitizer is exposed to a specific wavelength of light by a laser, it produces a type of reactive oxygen that can kill the cancer cells. This effect is similar to radiotherapy, but less invasive, less toxic and more specific.

Photodynamic therapy might also help destroy the nearby blood vessels which feed the cancer cells. This then prevents the cancer cells from receiving necessary nutrients to survive. Secondly, the process of photodynamic therapy can also activate the immune system and prompt immune cells to attack the cancer cells. This is especially synergistic with advanced immune therapies such as dendritic cells and checkpoint inhibitors. 



Photodynamic therapy is usually recommended for patients with small tumors. The limiting factors of this therapy may depend on the location (endoscopic/interstitial access) and the required penetration depth. Coming from the treatment of superficial skin cancers, it is still a relatively new treatment approach for other cancer types. However, it is becoming more widely recognized as an effective option beyond skin cancer, including cancer of oral cavity, esophagus, stomach, pancreas, colorectum, prostate, breast, uterus, bladder, muscles and bones. At Esperance, it is performed as an outpatient procedure where it can be repeated and adopted with other therapies such as surgery, radiation and cytotoxic treatments. 



Depending on the applied photosensitizer, an increased sensitivity for sunlight may result from the treatment. For that reason, the patient is recommended to avoid direct sunlight or bright indoor lights for a certain period of time; however, normally not more than a couple of weeks. There may be local reactions at the tumor site due to inflammatory tissue responses such as swelling.