Skin Cancer Part Two
Basal Cell Carcinoma is the most common skin cancer in the United States. Small lesions can be taken care of by MOHS micrographic surgery or surgical excision. The breakthrough for the large lesions not amenable to surgery, or for metastatic disease, is a newly FDA approved drug called vismodegib. This drug targets the hedgehog signaling pathway that is present in more than 90% of basal cell carcinoma. Vismodegib shrank advanced basal cell cancers in 43% of patients. Vismodegib is also effective in patients with Basal Cell Nevus Syndrome that have genetic predisposition to develop basal cell cancers, it is an oral drug taken on a daily basis. The major side effects from vismodegib are fatigue, diarrhea and hair loss.
Squamous cell carcinoma of the skin, if the lesions are small, can be taken care of by laser/freezing or surgery. Topical 5FU can be useful as well. For deep and large tumors radiation treatment can be useful. Metastatic squamous cell carcinoma of the skin is rare, therefore experimental protocols are not available. Metastatic disease usually responds to chemotherapeutic agents used for squamous cell cancer of head and neck and cervix.
For years the outlook for metastatic melanoma was grim with treatments like interlukin 2, interferon and dacarbazine that had very low response rates and very high toxicity profile.
Currently the increasing knowledge on the biology of melanoma has broadened the therapeutic options. It is now known that mutations in the BRAF gene causes the overexpression of the BRAF protein which in turn leads to tumor proliferation. The BRAF protein is currently the target of new therapies for advanced melanoma.
Vemurafenib is an oral drug recently FDA approved for metastatic melanoma patients with the BRAF mutation. This drug has a very high response rate with a long duration of response of almost two years.
Another recent breakthrough in melanoma treatment is a monoclonal antibody called ipilimumab, which stimulates the immune system. Ipilimumab targets the T-cell regulation causing even complete responses in some patients.
Several vaccines are currently being developed increasing knowledge of mechanisms and pathways that promote tumor growth and will continue to increase the therapeutic options for all types of skin cancer.