“This technique requires that the Mohs-trained physician, most often a dermatologist, serve as surgeon, pathologist, and reconstructive surgeon, all at the same time,” said Dr. Greenway. “As each layer of tissue is excised, it is immediately examined under a microscope and color-coded with immunostains for mapping purposes. Tissue is continually removed and examined, one layer at a time, down to the roots, until the samples are cancer-free. This spares the surrounding normal skin tissue and ensures 100-percent clear margins. Reconstruction of the wound can be done at the same time.”
Explore This IssueSeptember 2006
Guidelines for the treatment of melanoma are found in the NCCN’s Clinical Practice Guidelines in Oncology, Melanoma (available online at www.nccn.org/professionals/physician_gls/PDF/melanoma.pdf ). Treatment involves a much wider excision (0.5–2.0 cm), and sentinel node biopsy is recommended for melanomas >1.0 mm. If the sentinel node is negative, then regional lymph node dissection is not indicated. If it is positive, then a completion lymphadenectomy of the nodal basin is recommended. The NCCN-recommended adjuvant options include a clinical trial, high-dose adjuvant interferon alfa-2b or observation for patients with either localized melanomas (>4.0 mm) who are at significant risk for recurrence or positive nodes. CO2 laser ablation may be used in selected patients.
Promising New Treatments
Although BCC and SCC are commonly treated with surgery and radiation, local therapy, such as 5-fluorouracil (5-FU) (Effudex) and imiquimod (Aldara), are now being considered. 5-FU is a standard chemotherapy drug and imiquimod is an immune response modifier that promotes the release of cytokines that help to destroy cancer cells; both are manufactured as a cream, which makes them easy to use.
“5-FU and imiquimod are being applied topically to treat AK [actinic keratoses], superficial BCC, and Bowen’s disease,” said Dr. Greenway. A randomized phase III clinical trial is under way to see how well topical imiquimod works compared to surgery in treating BCC.
“One of the other promising areas of investigation involves the use of varying electrical pulses combined with intralesional drug therapy to treat non-melanoma skin cancers,” said Dr. Greenway. “We have been involved with electrochemotherapy (ECT) utilizing bleomycin sulfate intralesionally with the electrical current in BCC. In our study, six out of seven patients demonstrated complete cure, with a partial response for the other patient.”
Attacking Cancer with Light, Chemo
“Photodynamic therapy (PDT) is also being used to treat AK and some non-melanoma skin cancers in clinical trials,” said Dr. Weber. According to the National Cancer Institute, PDT involves a two-step process that uses a photosensitizer drug and light to create a chemical reaction that destroys only the cancer cells. For skin cancer, the drug is administered topically and is absorbed by both healthy and abnormal cells. After a predetermined period of incubation, the photosensitizer is activated by a specific wavelength of light (from a laser or other source, such as light-emitting diodes) that is directed at the cancer and produces oxygen that kills the abnormal cells. Simultaneously, PDT damages the blood vessels in the cancer, thereby cutting off its source of nutrients and it also activates the immune system to attack the cancer cells.
“Through multidisciplinary consultation, we can offer patients a wider armamentarium of treatment modalities in order to do what’s best for them.” – —Hugh Greenway, Jr., MD