Mohs micrographic surgery – named after Frederic E. Mohs, M.D., the physician who developed the technique – is a specialized surgical treatment that is designed to remove skin cancer while saving as much healthy tissue as possible. It offers a high five-year cure rate – up to 99% for basal cell carcinomas and up to 97% for squamous cell carcinoma.
Patients are generally referred by their primary care physician, internist or dermatologist for Mohs surgery. Self-referred patients are accepted if a biopsy has already been performed.
Skin cancer is the most common form of malignancy in man. It is estimated that this year alone, more than 5 million people will be diagnosed with basal cell carcinoma, squamous cell carcinoma and malignant melanoma – the three primary forms of skin cancer.
Frequently asked questions
What is Mohs micrographic surgery?
The late Frederic E. Mohs, M.D., developed the Mohs micrographic surgery technique in 1956. While this technique has been refined through the years, its goals have remained the same: to precisely excise all of the tumor, including roots that may be hidden to the naked eye, while preserving as much healthy tissue as possible.
Mohs surgery ensures that the tumor is removed by immediate microscopic examination of the entire surgical margin. If tumor is noted after initial excision, another layer of tissue is taken. This continues until a cancer-free plane is achieved.
Mohs surgery greatly diminishes the chance for cancer recurrence compared to other techniques.
At the same time, this technique produces smaller wounds and, hence, offers improved wound reconstruction opportunities (i.e., smaller scars) because only tissue that contains cancerous cells is removed. This aesthetic benefit is of particular importance because the majority of skin cancers develop on highly visible areas of the body, particularly the face, which have received the greatest amount of sun exposure. (Other possible causes of skin cancer include X-rays, chronic ulcers/sinus tracts, burn scars, certain chemicals, and a compromised immune system, i.e., in transplant patients.)
When is Mohs micrographic surgery indicated?
Several effective methods are used to treat skin cancer with reasonably high cure rates, but Mohs surgery produces the highest success rates. Mohs micrographic surgery is used primarily to treat basal cell and squamous cell carcinomas but may be used to treat less common tumors as well.
Approximately 75-80% of all skin cancers are basal cell carcinomas; approximately 15 -20% of skin cancers are squamous cell carcinomas.
The American College of Mohs Surgery, the preeminent organization governing fellowship-trained Mohs surgeons, cites the following current indications for Mohs surgery:
- The cancer was treated previously and recurred
- Scar tissue exists in the area of the cancer
- The cancer is in an area where healthy tissue must be preserved for maximum functional and cosmetic results, i.e., eyelids, nose, ears, lips, fingers, genitals, etc.
- The cancer is large
- The edges of the cancer cannot be clearly defined
- The cancer grows rapidly or uncontrollably
Is this a new technique?
In 1982, Washington University School of Medicine became the first treatment facility in Missouri to offer Mohs micrographic surgery and remains among a select group of medical centers in the country equipped to offer this form of treatment by fellowship-trained physicians. At Washington University, we treat more than 3,000 skin cancers with Mohs surgery each year.
How is Mohs micrographic surgery performed?
Patients are generally referred for Mohs surgery after a suspicious lesion is biopsied, a pathology report confirms the presence of skin cancer, and one or several of the previously mentioned indications are noted.
Once the obvious tumor is excised, the Mohs surgeon removes an additional thin layer of tissue and creates a color-coded map of the site to be used as a guide to the precise location of any remaining cancer cells on the patient. After the tissue is processed, it is examined under a microscope. If any section contains cancer cells, the surgeon will return to the waiting patient and remove another thin layer of tissue from this exact location only. The newly removed tissue is then color-coded, processed and examined under the microscope as above.
Should additional cancer cells be present, this process will be repeated until the cancer is completely gone. The goal is to eradicate all tumor roots on the day of the surgery.
Where is Mohs micrographic surgery performed, and how long does it take?
Mohs surgery is performed on an outpatient basis, in the physician’s offices at the Center for Dermatologic and Cosmetic Surgery in West County or the Center for Outpatient Health at Barnes-Jewish Hospital, with only a local anesthetic injected into the tumor site. This process is quite precise and can be time-consuming. It takes approximately 20 – 30 minutes for a layer of tissue to be removed and 1 hour for each layer of tissue to be prepared into microscopic slides and examined. On average, patients require removal of two to three layers of tissue to ensure that all cancer cells are gone.
Many patients undergo Mohs surgery in the morning and wound reconstruction the same afternoon by our team or an appropriate reconstructive surgeon. Occasionally, a patient will need to return to our clinic or that of a reconstructive surgeon on a second day to complete the process.
How are postoperative wounds managed?
Once the entire cancer is removed, your Mohs surgeon – or other reconstructive surgeon (i.e., plastic surgeon or oculoplastic surgeon) as decided upon at the time of consultation – will discuss wound-management options that will achieve the best results in preserving functional capabilities and maximizing aesthetics.
Mohs surgeons are trained in reconstructive procedures and often will repair the wound with stitches, a skin graft or skin flap. In some cases, the wound is allowed to heal by itself – a process that requires daily bandage changes for two to six weeks.
Is Mohs micrographic surgery covered by my health insurance? Is this a cost-effective procedure?
Most major health insurance companies cover Mohs micrographic surgery, although we always advise patients to check with their provider before making an appointment.
Mohs surgery has been shown to be cost-effective. Because Mohs surgery minimizes skin removal, repairs are often simpler and involve less complicated reconstructive procedures. With its higher cure rates, Mohs surgery also minimizes the need for larger, more serious surgeries to treat recurrent cancers.
How do I prepare for Mohs micrographic surgery?
No real preparation is needed, other than a good night’s sleep. You should eat a light breakfast on the day of surgery. If you are currently taking medication, continue as usual unless directed otherwise by your physician.
Eliminate aspirin or any medications containing aspirin, for a least two weeks before surgery. This is because aspirin tends to prolong bleeding during the operation. Vitamin E, Gingko Biloba, garlic tablets, St. John’s Wort and your daily multivitamin can also increase bleeding and must be stopped 2 weeks before surgery.
Also, eliminate medications containing ibuprofen, commonly found in Advil, Nuprin and Motrin, for at least one week before surgery. If you need a pain reliever, you may take acetaminophen, which is found in Tylenol.
On the day of surgery, it is best to wear a shirt that buttons down the front. No makeup or jewelry should be worn if surgery is to be performed on your face.
Bring one friend or relative with you, since you will spend most of the day in the waiting room while the microscopic slides are prepared and interpreted. Because our waiting areas are small, we recommend only one other person attend with you. Otherwise, we recommend you bring a good book or some magazines.
How do I select a surgeon to perform Mohs micrographic surgery?
Mohs surgeons are specialists in dermatology, pathology and reconstructive surgery. After completing a residency in dermatology, physicians are eligible for additional Mohs micrographic surgical training, and the minimum fellowship-training period is one year. If your doctor is a fellow of the American College of Mohs Surgery, you can be assured that he or she has received the highest level of training in this subspecialty area.
What can I do to prevent future skin cancers?
Minimize your exposure to the sun by applying a sunscreen with a minimum sun protection factor (SPF) of 30. It should be applied 20 minutes before you go outdoors. Sunscreen is under-utilized by the majority of individuals. Be sure to use it liberally and often.
Wear a hat with a broad brim (greater than 6 inches), and avoid direct exposure to the sun between 10 a.m. and 4 p.m.
Be sure to visit your dermatologist for yearly checkups – especially if you have had a skin cancer in the past or have numerous moles, since these conditions increase your risk of skin cancer. If you notice any suspicious areas on your skin between visits, ask your physician if a biopsy might be needed.