Mohs surgery is the most advanced and effective method for skin cancer removal. It has the highest cure rate for complex skin cancers while at the same time minimizing the removal of normal surrounding skin. It is used to treat certain skin cancers that develop on cosmetically sensitive locations (face, hands, etc), in patients with immunosuppression (organ transplant, leukemia, HIV infection), have returned after previous treatment, are of large size, and have edges that are ill-defined.
Processing the tissue with a special technique, the skin cancer is removed layer by layer until cancer-free tissue (or clear margins) is reached. It is a highly specialized and precise procedure that differs from routine surgical excision, when only ~1% of margins are evaluated and results can take up to a week to return.