Photodynamic Therapy for Cancer

Photodynamic therapy combines a special drug, known as a photosensitizing agent, and a certain light to kill cancer cells. Some of the drugs are applied topically such as aminolevulinic acid (ALA) and methyl ester of ALA. However, the most commonly used is injected into the blood vessels. It is called porfimer sodium and this type of treatment will be the focus of this article. It is non-toxic and absorbed by both healthy cells and cancerous cells. However, when exposed to a certain light the drug activates, killing the cancer. Photodynamic therapy (PDT) is sometimes named phototherapy, photoradiation therapy, and photochemotherapy.

Preparation for Photodynamic Therapy: It’s advisable to get your body used to the light sensitivity it will be experiencing later. Cover the windows and turn off the lights in your home before your Photodynamic therapy appointment. Before you leave, it is important to wear socks, long pants and a long sleeved top to your appointment. Your clothes should be of a tight knit fabric and light in color. Also, bring along gloves, sunglasses and a hat with a wide brim that goes all the way around.  

Procedure: The time it takes for the drug to absorb into the cancer cells is known as the drug-to-light interval and can take hours to days. Over time the body cleanses itself from the drug.  

To activate the drug, a laser is sent through a thin fiber optic strand made of glass and is directed to the cancerous cells. The light makes oxygen and the drug react together to create a chemical that kills cancer cells. How the strand reaches the affected area depends on the type of cancer. For example, the strand is placed in the throat with an endoscope when treating esophageal cancer. With lung cancer, it is put into a bronchoscope so it can be fed into the lungs. The whole procedure is fairly quick and typically outpatient. 

A low powered laser means that pain is minimal or even nonexistent with Photodynamic therapy. The light is applied anywhere between 5 to 40 minutes, depending on how big the tumor is. In less than a week, dead tissue can be taken out.  

Types of or Techniques Used: There are many ways in which Photodynamic therapy is used. Besides targeting cancer directly, it can cut off the cancer’s food source by destroying the blood vessels which feed it. PTD can even turn the body’s own immune system to fight against the cancer.  

Recovery Time: The procedure is typically painless and can even be repeated in the same area for multiple treatments. After healing there is little or no scarring. However, you may feel sensitive to light up to 30 days after the procedure. Be careful about how much time you spend outside. Also, watch your exposure to reading lamps and doctor’s examination lamps. High heat can also activate the photosensitizing agents still in your body, so be careful with hair dryers, and other heat sources.  

Risks and Side Effects of Photodynamic Therapy: Though there are no long-term side effects, Swelling is a common complaint of Photodynamic therapy. It can cause problems with breathing and swallowing and may be painful. Light sensitivity of the eyes and skin is also common due to the photosensitizing agents used.  

While your body is cleansing itself of the drugs, you may find that your eyes and skin are very sensitive to light. Just a few minutes in the sun can cause burning and blistering. Your eyes may not only be more sensitive to sunlight but also other forms of light as well.  

Avoiding the sun is a must but some indoor light exposure is necessary. This helps break down the drug in your skin. After about 30 days, if you’re concerned, a doctor can test your skin to see if you still have photosensitivity from PDT.  

General side effects can vary from person to person. For example, esophageal cancer treatment may cause stomach upset, vomiting, elevated temperature, or mild to severe dehydration. With lung cancer PDT treatments you may experience bloody phlegm, pneumonia, or problems breathing.  

Remember, everyone’s experience is unique so ask your doctor what to expect with your Photodynamic therapy procedure.