Photodynamic Therapy

Photodynamic Therapy

Photodynamic therapy is a medical technology used by dermatologists to treat certain types of skin cancer

Photodynamic therapy (PDT) is a medical technology developed in the 1980s used by dermatologists to treat certain types of skin cancer. PDT can be as effective as cryotherapy, curettage, radiotherapy and fluorouracil in treating solar keratoses on the face and scalp, and superficial basal cell carcinomas. It is also approved to treat wet macular degeneration and being investigated for treatment of psoriasis.

PDT works by using photosensitising agents (drugs that are administered into the body through topical, oral or intravenous methods), oxygen and light, to create a photochemical reaction that selectively destroys cancer cells. In the body, photosensitising agents concentrate in cancer cells and only become active when light of a certain wavelength is directed onto the area where the cancer is. The reaction between the photosensitising agent, light and oxygen kills the cancer cells. Unlike chemotherapy for cancer the effect of PDT can be localised. It can also be much cheaper than the alternative radiotherapy or surgical operation and after care. However, the light needed to activate most photosensitizers can not penetrate through more than one third of an inch of tissue, therefore treatment is limited to tumors on or under the skin, or on the lining of some internal organs and is less effective against large tumors.

Side Effects

Photosensitivity usually lasts around 24 hours. Side effects may include burning/stinging sensation, swelling and redness, crusting, itchiness, peeling and blisters, and skin infections.

Notes of Precaution

The treated area should be protected from light exposure using a dressing.

A local anesthetic may be applied to the treatment area before or during treatment to relieve pain.

The treated skin lesion may blister and ulcerate as the cancer cells die off, and it may take several weeks to heal.

Loss of pigmentation may occur and may be permanent.

The photosensitising agents may make healthy cells sensitive to sunlight, as well. It's best to avoid prolonged exposure to sunlight for weeks after treatment, and wear protective covering.