09 November 2011

Photodynamic Therapy: Shining A Light To Fight Cancer

Photodynamic Therapy or PDT is a clinical procedure that is used to against certain medical conditions including cancer.

It involves using light wavelengths to target and destroy selected cells and tissues. This procedure is both minimally non-invasive and non-toxic.

Recently, a study published by the National Cancer Institute showed a promising next step in PDT. Using a combination of antibodies and near infra red light, PDT can be adjusted to hit only specific cells rather than an area. The researchers used an antibody that targets specific proteins on the surface of the cancerous cells. These stick to the cell and hit by near infra red light that causes damage to these cells but not the surrounding tissue.

The study is published in Nature Medicine.

Three components used in modern PDT applications are the photosensitizer, the light source, and tissue oxygen. The light's wavelength should be adjusted to excite the photosensitizer to produce reactive oxygen species. The combination of these destroys the tissue on the chemical level. Other light based treatments such as lasers and skin rejuvination are different from PDT since these do not use or need a photosensitizer. A photosensitizer is a light-absorbing substance that starts a photochemical or photophysical reaction in the tissue.

Video: Photodynamic Therapy

The limiting factor of Photodynamic Therapy is that the light used by the treatment cannot penetrate deeply. Current technology has light wavelengths usually reaching to about 1cm deep into the tissue. To achieve greater light penetration, hollow needles are used to get light into deeper tissues. Another way is using new high powered LED technology.

But with this new study involving anti-bodies, PDT can be used to greater efficiency and even be used to treat other forms of cancer.

Dr Laura McCallum is Cancer Research UK's science communications officer. She says, "Using antibodies or photodynamic therapy to specifically target cancer cells have both been successful for treating some cancers, so combining the two together is certainly an exciting plan... This potential treatment has promise as scientists - including our own - are also looking at using antibodies to deliver other knockout punches, such as radiation, directly to cancer cells."

Other treatments using PDT is acne,

There are other studies being conducted that are revolutionizing the fight against cancer. Some of these include using vaccines that target cancer cells and embryonic stem cell treatment.