Photo Dynamic Therapy
PDT is a minimally invasive treatment for cancer. It can be applied before or after chemotherapy, surgery, or radiation without conflict. It can be repeated as often as necessary, without causing treatment resistance by the tumour.(1)
PDT uses light from a specific wavelength (usually red or infrared on the light spectrum chart), which triggers photosensitive drugs (including 5-ALA, Tookad, Photofrin, among others). The drugs are administered in different ways depending on the cancer, and have an affinity for tumour cells, thus causing an increased accumulation in the tumour. When the specific light is applied, it causes a sequence of chemical reactions to occur which attacks the tumour and destroys it from the inside out.(2). There is also some evidence indicating that photodynamic therapy may help to destroy tumours in two other ways. Firstly, the photosensitizer can damage blood vessels in the tumour, thereby preventing the cancer cell from receiving necessary nutrients. Secondly, PDT may activate the immune system to attack the tumour cells.(3)
PDT is not new. It has been used in various forms since the early 1900s, though modern forms of photosensitive drugs have been around since the 1970s. In addition to skin cancers, PDT has already been shown to improve survival in patients with unresectable cholangiocarcinoma(4), and certain lung cancers(5). Research is being conducted today in centres across Canada, including London Cancer Centre, Juravinski Cancer Centre, Princess Margaret Hospital and McGill University.
Until recently, PDT has been inhibited by the lack of superior photosensitizing agents and the quality of light forms available. This has been particularly true for the treatment of deeper tissue tumours. Today, with the development of leading-edge light therapy by Kerber Applied Research of Ontario, effective treatment of deep tissue cancers such as liver, pancreas, lung, etc., is now possible using photodynamic therapy. The Kerber technology allows for specific light to penetrate several centimetres into body tissue, thus enabling activation of the sensitizer drug, causing destruction of cancer cells. This innovative LED technology now opens up a whole new field in photodynamic therapy, which expands the scope of this non-toxic, clinically proven safe therapy for cancer.
This is a very exciting tine for cancer treatment innovation. A treatment method that also includes preventing damage to normal cells is a modality whose time is very welcome, though overdue. Photodynamic therapy is proving to be an excellent tool in the treatment of many previously difficult-to-treat cancers, and one without the toxicities of many orthodox therapies.
To find out more, call United Medicine Group at 416-385-9900.
References:
1. Lancet Oncology-Dec. 2001-1:212-9éPDT-Clinical Reality in the Treatment of Cancer
2. Killing Cancer Canada-Photodynamic Therapy
3. National Cancer Institute-Photodynamic Therapy for Cancer-Fact Sheet:
a)Dolmans DEJGJ, Fukumura D, Jain RK. Photodynamic Therapy for Cancer. Nature Reviews Cancer 2003; 3(5):380-387
b)Wilson BC. Photoodynamic Therapy for Cancer: Principles. Canadian Journal of Gastroenterology 2002;16(6):393-396
c)Vrouenraets MB, Visser GWM, Snow GB, van Dongen GAMS. Basic Principles, Applications in Oncology and Improved Selectivity of Photodynamic Therapy. Anticancer Research 2003; 23:505-522
4. Clinical Gastroenterology and Hepatology 2008; 6:266-267 and 290-297 (abstract)
5. Chest 2002: Abstract p366. Presented Nov. 6, 2002
