How Does Melanoma Treatment Work?
Melanomas that are caught early (before they have invaded too deeply under the skin, measured by the “Breslow depth”), are typically treated and cured with surgery under local anesthesia by a dermatologist or dermatologic surgeon. Until recently, the only surgical option available to treat melanomas was a conventional ‘wide local excision’ where the dermatologic surgeon cuts around the melanoma with a margin of safety (typically 1cm for thinly invasive melanomas and between 0.5cm-1cm for in situ melanomas). The specimen is then sent to the lab to check that the margins are clear.
In the past decade, the Mohs surgery technique, initially used for non-melanoma skin cancers such as basal cell carcinomas and squamous cell carcinomas, has been shown to offer some melanoma patients a higher cure rate than conventional wide local surgery. This procedure is mainly used for melanomas on the head and neck, genitalia, or hands and feet. During Mohs surgery, the Mohs surgeon will cut around the melanoma with a margin of safety, and the tissue is processed in the office by a trained histotechnician.
In addition to removing the melanoma, the Mohs surgeon usually also takes a small biopsy from somewhere else on your skin to serve as a control. While the tissue is processing, you will wait in the exam room or in the waiting room.
Mohs for melanoma requires the histotechnician to use special stains so that the Mohs surgeon can visualize the melanocytes, the cells that form melanoma. Once the tissue is processed, the Mohs surgeon will look at the tissue under the microscope and compare it to the control tissue to ensure that the melanoma is completely removed. If there is any residual melanoma, the surgeon will go back and remove more tissue just from that area. Once the cancer is fully removed, the Mohs surgeon will discuss options to reconstruct the wound (see ‘Wound Care’ and ‘Flap and Grafts’).
Mohs surgery has been shown to have a better cure rate for thinly invasive or in situ melanomas on specialty sites such as the head, neck, genitalia, or hands and feet compared to conventional excision, with a <1% recurrence rate as compared to an ~10% recurrence rate with conventional wide local excisions. It also has the advantage of being ‘tissue sparing’, meaning that at times the final scar is smaller than it would be with conventional wide local excision.