Review on mucosal melanoma

In this study the authors reviewed different treatment options, causes and outcome of mucosal melanoma – a form of cancer that affects mucous membranes like the nose, mouth, vagina and anus. 

Mucosal melanoma is a rare cancer that occurs in particular tissues in the body (mucosal), lining the head and neck, nostrils, oral cavity, vagina, anus and other areas. It is an aggressive form (fast-growing) of cancer that usually needs surgery when detected. In most of the mucosal melanoma patients, mutations (permanent change) in a gene called C-KIT (an important protein involved in cell growth) are detected. For these patients, C-KIT inhibitor (drug that will stop the growth of cancerous cells) is a treatment option.

Mucosal melanoma is distinct from other types of skin cancer and requires different treatment approaches and classification system. Like other melanomas, the risk factors, cause and origin of mucosal melanoma need to be well established.

The authors aimed to re-examine different types of mucosal melanoma, their treatment options and survival benefits.

In a study of 815 patients with mucosal melanoma of head and neck, the average 5-year survival rate was 24.2%. Patients over 70 years of age and tumor size > 2 cm had worse overall survival. In cases where cancer had spread to nearby lymph nodes (tiny, bean-shaped organs which help fight infections) of the neck, local surgery of the tumors along with complete removal of the affected lymph nodes were carried out. But this did not improve overall survival compared to local surgery alone.

In mucosal melanoma of anorectum (anus and rectum), local bleeding was the most common symptom in a group of 40 patients. In another study of 142 patients over 30 years, the 5-year survival rate was 26.7% with localized disease (cancer has not spread from original site), 9.8% with regional spreading of cancer (cancer is moving away from the original site) and 0.0% with distant metastasis (the cancer has reached distant organs). Surgery remains the standard treatment in this type of mucosal melanoma. A wide local excision (surgery on area of diseased tissue with a margin of normal tissue) or complete removal of anus, rectum and part of colon improved overall survival. 

In addition to surgery, chemotherapy and immunotherapy (treatment that uses body’s own immune system to help fight cancer) are standard options to treat mucosal melanoma. C-KIT inhibitors also showed promise in improving survival in mucosal melanoma patients. In phase II clinical trials of imatanib (Gleevec), a C-KIT inhibitor, the average overall survival was reported to be 10.7 to 12.5 months.  Either partial or complete disappearance of tumor was reported in 16 to 20% of patients.

The authors concluded that treatment options for metastatic mucosal melanoma are limited due to the rarity of the disease. C-KIT inhibitors could be a promising therapy for those patients who carry the specific genetic mutation.