• 7/11/2003
  • Baltimore, MD

The American Cancer Society says there will be about 30,000 new cases of oral cancer diagnosed this year. Nearly one-third will be cancers of the throat. Surgery is standard treatment. Now, a special light can kill the cancer.

Two years ago, Allison Jaccard was diagnosed with cancer of the larynx. Although this type of cancer is usually thought to be in people who have smoked for years, Jaccard was never a smoker or a drinker. She had surgery, but it didn’t get all the cancer. Then Jaccard was offered an alternative treatment at the University of Maryland using laser light therapy.
“It is extremely exciting, I will tell you, for several reasons, not the least of which it’s working,” says Paul Castellanos, M.D., a head and neck surgeon at University of Maryland.

Dr. Castellanos uses a light-sensitive drug activated by a laser to destroy cancer cells. Through this device, the laser is directed to the cancer cells, killing them while healthy cells survive. The laser activates the drug to produce a toxic form of oxygen that kills the cancer. He says, “It’s allowing us to take care of cancers of the throat and oral cavity without having to do ablations of those tissues that can have a devastating effect on the patient’s voice.”
In a University of Maryland study of people with early stage cancers of the mouth, throat and larynx, after one treatment, nearly 90 percent showed no evidence of the disease. It worked for Jaccard. She’s been cancer-free since getting the treatment. “The thing that it’s done for me is to make you realize just how precious everything you have is,” she says. “So, it just gives you a perspective of what’s important.” Dr. Castellanos says the main side effect of the treatment is an extreme sensitivity to sunlight. Patients are required to stay completely out of the sun for up to six weeks. The light sensitive drug reacts to red light from the sun, so sunblock will not work.

OCF NOTE: PDT has been around for about 8 years, it is just now going through clinical trials for oral cancers at some institutions, and that is likely the reason that Baltimore put out this news article. Photodynamic therapy (also called PDT, photoradiation therapy, phototherapy, or photochemotherapy) is a treatment for some types of cancer. It is based on the discovery that certain chemicals known as photosensitizing agents can kill one-celled organisms when the organisms are exposed to a particular type of light. PDT destroys cancer cells through the use of a fixed-frequency laser light in combination with a photosensitizing agent.

In PDT, the photosensitizing agent is injected into the bloodstream and absorbed by cells all over the body. The agent remains in cancer cells for a longer time than it does in normal cells. When the treated cancer cells are exposed to laser light, the photosensitizing agent absorbs the light and produces an active form of oxygen that destroys the treated cancer cells. Light exposure must be timed carefully so that it occurs when most of the photosensitizing agent has left healthy cells but is still present in the cancer cells.

The laser light used in PDT can be directed through a fiber-optic (a very thin glass strand). The fiber-optic is placed close to the cancer to deliver the proper amount of light. The fiber-optic can be directed through a bronchoscope into the lungs for the treatment of lung cancer or through an endoscope into the esophagus for the treatment of esophageal cancer.

An advantage of PDT is that it causes minimal damage to healthy tissue. However, because the laser light currently in use cannot pass through more than about 3 centimeters of tissue (a little more than one and an eighth inch), PDT is mainly used to treat tumors on or just under the skin or on the lining of internal organs.

Photodynamic therapy makes the skin and eyes sensitive to light for 6 weeks or more after treatment. Patients are advised to avoid direct sunlight and bright indoor light for at least 6 weeks. If patients must go outdoors, they need to wear protective clothing, including sunglasses. Patients should talk with their doctor about what to do if the skin becomes blistered, red, or swollen. Other temporary side effects of PDT are related to the treatment of specific areas and can include coughing, trouble swallowing, abdominal pain, and painful breathing or shortness of breath.

In December 1995, the U.S. Food and Drug Administration (FDA) approved a photosensitizing agent called porfimer sodium, or Photofrin®, to relieve symptoms of esophageal cancer that is causing an obstruction and for esophageal cancer that cannot be satisfactorily treated with lasers alone. In January 1998, the FDA approved porfimer sodium for the treatment of early nonsmall cell lung cancer in patients for whom the usual treatments for lung cancer are not appropriate. The National Cancer Institute and other institutions are supporting clinical trials (research studies) to evaluate the use of photodynamic therapy for several types of cancer, including cancers of the bladder, brain, larynx, and oral cavity. Researchers are also looking at different laser types, photosensitizers that can be applied to the skin to treat superficial skin cancers, and new photosensitizing agents that may increase the effectiveness of PDT against cancers that are located further below the skin or inside an organ.