Mohs surgery accomplishes the nifty trick of sparing the greatest amount of healthy tissue while also most completely expunging cancer cells; cure rates for BCC and SCC are an unparalleled 98 percent or higher with Mohs, significantly better than the rates for standard excision or any other accepted method.
The reason for the technique’s success is its simple elegance. Mohs differs from other techniques in that microscopic examination of all excised tissues occurs during rather than after the surgery, thereby eliminating the need to "estimate" how far out or deep the roots of the skin cancer go. This allows the Mohs surgeon to remove all of the cancer cells while sparing as much normal tissue as possible. The procedure entails removing one thin layer of tissue at a time; as each layer is removed, its margins are studied under a microscope for the presence of cancer cells. If the margins are cancer-free, the surgery is ended. If not, more tissue is removed from the margin where the cancer cells were found, and the procedure is repeated until all the margins of the final tissue sample examined are clear of cancer. In this way, Mohs surgery eliminates the guesswork in skin cancer removal, producing the best therapeutic and cosmetic results.