Photodynamic Therapy

At Penn Medicine's Abramson Cancer Center, our radiation oncologists and other cancer specialists are experienced in using light-sensitive medication together with low-level beams of light to destroy cancer cells. We were the first institution in the Delaware Valley with this technology.

Photodynamic Therapy (PDT), also known as photoradiation therapy, phototherapy, or photochemotherapy is used to treat certain types of cancer. It is based on the discovery that certain chemicals known as photosensitizing agents can kill organisms when they are exposed to a particular type of light. PDT destroys cancer cells through the use of a fixed-frequency laser light (an intense narrow beam of light) in combination with a photosensitizing agent.


  • 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.
  • 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.
  • 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.

PDT causes minimal damage to healthy tissue. However, because the laser light currently in use cannot pass through more than about three 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.

The Advantage to Patients

Research shows the advantages of PDT include:

  • Minimal damage to healthy tissue
  • Less invasive than surgery
  • Precise targeting of cancer cells
  • Ability to repeat treatments to the same site
  • Less scarring

Type of Cancer Treated with PDT

Currently, photodynamic therapy is being by Penn Cancer Services to treat:

Treatment Sessions

Radiation therapy offers patients a noninvasive cancer treatment option. There's no pain during the procedure (though some patients with physical limitations may experience some discomfort when positioned), very little noise, and no time spent inside small, confining spaces, as with some technology.

At the start of each session, a radiation therapist will spend 5 to 15 minutes positioning the patient for treatment and setting up the equipment as instructed by the radiation oncologist. X-rays are taken to insure that the patient is in the proper treatment position. Once the patient is in position, the therapist will enter the control room next door. From here, the patient is monitored throughout the treatment on a television screen and via voice communication. Should the patient have any concerns, or feel sick or uncomfortable, this may be expressed to the radiation therapist using the microphone located in the treatment room.

Depending upon the individual patient's circumstances, a course of radiation therapy usually runs five days a week for several weeks. Generally, the patient is at Penn Radiation Oncology for about an hour each day with the actual radiation therapy session lasting 15 to 30 minutes.

Patients are seen at least once a week by a Penn radiation oncologist. During this appointment, the radiation oncologist evaluates a patient's response to treatment. As needed, the amount of radiation administered to the patient is altered based upon the radiation oncologist's observations. Blood work and X-rays may also be ordered to see how a patient's body is responding to treatment. If a patient's tumor shrinks significantly, another simulation may be required. This allows adjustments to be made to the treatment so that the rest of the tumor is destroyed while sparing even more normal tissue.