Skin cancer is becoming more prevalent, and it is estimated that about twenty percent of people worldwide will develop skin cancer in their lifetime. Fortunately, skin cancer has a high recovery rate and is rarely lethal when diagnosed and treated early. For certain types of skin cancer, the treatment recognized as having the highest cure rate is known as Mohs micrographic surgery, or simply, Mohs surgery. The Mohs surgery technique incrementally removes cancerous tissue while sparing as much healthy tissue as possible.
Benefits of Mohs Surgery over Traditional Local Excision
Unlike skin cancer treatments that may remove large amounts of healthy tissue while excising cancer, Mohs surgery methodically removes cancer in increments to preserve healthy tissue. Sections of removed tissue are examined under a microscope to detect the extent of the cancer. If the cancer appears to extend beyond the borders of removed tissue, removal and examination continue until all cancerous tissue is eradicated. Skin cancer lesions can often be deceiving; what appears to be a small lesion at the skin surface may branch out with root-like extensions into deeper tissue layers. Methodical examination with a microscope allows the physician to determine exactly how far the tumor extends, while minimizing the removal of healthy tissue.
The Mohs surgery technique is used on many types of skin cancers. It is typically reserved for skin cancers that have a high risk of reappearing or for skin cancers that have already recurred. Mohs surgery is also performed to remove large cancers, cancers that are aggressive or have rapid growth, cancers with poorly defined margins and cancers occurring in scars. The procedure is most frequently used for basal and squamous cell carcinoma, and also may be performed on select melanomas. It has a very high success rate, particularly in the case of squamous and basal cell carcinomas, achieving a 97-99 percent cure rate. Mohs surgery is also a preferred option for removing skin cancer from areas such as the face, hands, feet, and genitals, where preserving a maximum amount of healthy tissue is important for maintaining function and minimizing scarring.
At the beginning of the procedure, the physician creates a reference sketch of the visible cancer and the surrounding skin. Next, the affected area is marked and numbed with a local anesthetic. The visible tumor is excised using either a scoopshaped device, known as a curette, or another surgical instrument. Once the visible tumor is removed, the physician will cut a thin layer of underlying tissue from the tumor site to examine it and determine if cancer extends beyond the excision. This layer of tissue is cut into sections and the edges are color coded with a variety of dyes, which ensures the tissue can be oriented and mapped correctly. The excision area is bandaged, and you will be taken to the waiting room while the tissue is prepared and examined.
The removed tissue sections are frozen and the entire border and underside of each section is cut into fine slices and placed on microscope slides. The centers of the tissue sections do not need to be examined since they have already been removed and the goal is to identify if any cancer extends into the uncut tissue. The slices are stained to make the cancer cells identifiable, and then carefully inspected. If your physician determines that cancer cells extend to the border of any slice, the area is indicated on the reference map and another layer of tissue is removed from that area. This procedure of removal and examination continues until no more evidence of cancer is found. Two or three stages of this process are typical, but individuals may require several excisions depending on how extensively the cancer has spread.
The entire Mohs surgery is typically performed in a single session and may last several hours. Once the cancerous tissue has been eradicated, the area will be repaired. A small, shallow lesion may be allowed to heal by itself, while a larger lesion will typically be closed with sutures. For a very large lesion or one in a cosmetically sensitive area, such as the face, a flap of skin may be pulled over the lesion, or a skin graft may be necessary to reconstruct the incision area. Temporary numbness, tightness, and soreness are normal during recovery from Mohs surgery, and slight swelling and bruising may also occur. To minimize scarring after Mohs surgery, follow your physician’s instructions. Mohs surgery is a highly effective way to remove skin cancer while sparing as much healthy tissue as possible, thereby minimizing scarring and achieving a high cure rate. Consult your physician to see if Mohs surgery is right for you.