Mohs micrographic surgery is a technique that delivers the lowest recurrence rate of any skin cancer treatment method, the highest chance for a complete cure, and an optimal cosmetic result. Developed by Dr. Frederick Mohs in the 1930s, Mohs micrographic surgery has a cure rate of 98 percent or more for basal cell carcinomas and squamous cell carcinomas—the two most common types of skin cancers.
The Mohs micrographic surgery technique is designed to be tissue sparing. Through specialized training, your Mohs surgical dermatologist completely removes any cancer cells present at the surgical site, leaving behind only healthy, noncancerous skin. Since approximately 80 percent of basal cell and squamous cell carcinomas occur on the head and neck, Mohs surgery is extremely important because it helps to preserve the function and appearance of skin in highly visible parts of the body.
Not all skin cancers are appropriate for Mohs micrographic surgery. Small, superficial basal cell carcinomas or squamous cell carcinomas on the abdomen, chest, back, arms and legs are usually considered low risk. These cancers are typically treated with standard methods such as surgical excision, cryosurgery (freezing), curettage and electrodessication (scrape and burn), photodynamic therapy, and/or topical medications.
Areas that are considered high risk and most appropriate for Mohs micrographic surgery include cancers that affect the nose, eyelids, lips, ears, hands, feet and genitals; areas on the face, scalp, neck and shins are considered intermediate risk. Other skin cancers for which the Mohs micrographic surgery technique may be appropriate include the following:
- Recurring cancers or those never completely removed by other treatments
- Large cancers (even in normally low-risk areas)
- Cancers with poorly demarcated borders
- Distinct microscopic cancer cell patterns that suggest the cancer may be more aggressive
- Cancers occurring in patients with weakened immune systems caused by diseases such as leukemia and HIV/AIDS, or by medications such as transplant drugs
- Cancers that occur in patients with predisposing genetic syndromes
One key difference between Mohs micrographic surgery and routine excisional surgery is that the Mohs technique requires the tissue-sparing surgery to be completed in stages. The Mohs surgeon usually starts by confirming that the area being operated on has a skin cancer present. This is accomplished by comparing clinical photographs to previous biopsy reports. Next, the affected area is usually photographed, and the surgeon marks around the skin cancer with ink to help guide treatment. An anesthetic is used to numb the skin completely. Then, using a scalpel, the doctor removes a thin layer of visible cancer-containing skin and color-codes the removed tissue to create an “ink map” that correlates with the exact location on the body from where the tissue was removed. An assistant bandages the wound, and the patient returns to the waiting area.
Next, a technician processes the removed skin in an on-site Mohs micrographic laboratory. This includes freezing the skin and slicing the tissue into paper-thin sections that are placed on glass slides and stained. Your Mohs micrographic surgeon examines these slides under a microscope. If no cancer cells remain in a given area, then that area is deemed clear of cancer. If any cancer cells do remain, they’re pinpointed on a map. Then, the patient is brought back to the procedure room, and the Mohs surgeon removes another thin layer of tissue, repeating this process until the patient is cleared of cancer cells in all checked areas.
Unlike traditional excisional surgery, the Mohs process doesn’t require patients to wait days for lab results. Instead, your Mohs micrographic surgeon performs the entire procedure, including surgery and laboratory testing, while you remain on-site. The entire process may take several hours from start to finish, but it is worth it for the high cure rate!