given as nine intralesional injections over three weeks or, in a sustained-release form, as one or three intralesional injections per week.
Interferon leaves no surgical wound, has good cosmetic results and avoids bleeding and infection. Short-term side effects include fever, chills, muscle aches, headaches and nausea.
Photodynamic Therapy (PDT) This treatment uses visible light in combination with a photosensitizer, a compound that attracts light. The photosensitizer now being used is a hematoporphyrin derivative, HPD.
Approximately 48 to 72 hours after HPD is intravenously injected, most of the compound is cleared by the normal skin and selectively retained in the cancerous cells . Upon exposure to different colors of light, HPD undergoes a photodynamic reaction that damages the tumor cells and spares the uninvolved tissue . In practice, HPD is given as an intravenous injection and is followed 48 to 72 hours later by irradiation with red or blue-green light.
There are no well-controlled studies using HPD, but encouraging preliminary results have been reported in treating basal and squamous cell carcinomas.
A disadvantage of photodynamic therapy with HPD is that levels of HPD may stay in the normal skin for three to six weeks after the injection. During this time, patients need protection from all bright light, since exposure to light can result in severe redness and swelling of the skin. This adverse effect would be eliminated if an effective photosensitizer could be applied only to the affected area of skin.
