Clinical studies have shown that the cure rate for Mohs micrographic surgery is the highest of all treatments for previously untreated skin cancer – 99 percent and 95 percent for recurrent cancers.  As the most exact and precise method of tumor removal, this procedure minimizes the chance of regrowth and decreases the potential for scarring or disfigurement.  As such, Mohs surgery offers the highest potential for complete removal of the cancer, while sparing the surrounding healthy tissue. 

History

Developed by Frederic E. Mohs, MD, in the 1930s, the Mohs micrographic surgical procedure has been refined and perfected for more than half a century.  Initially, Dr. Mohs removed tumors with a chemosurgical technique.  This entailed the application of a chemical to the tumor before tissue was removed.  Because of this it was usually necessary to extend the surgery over the course of a number of days.  During this time, thin layers of tissue were excised, frozen and then pathologically examined.  The surgery included a unique technique for color-coding excised specimens and created a mapping process to accurately identify the location of remaining cancerous cells.

As the process evolved, surgeons omitted the chemical and refined the technique so that the surgery could be completed in one day.  This refinement also generally permits immediate reconstruction of the wound.  However, the color-coded mapping of excised specimens and the thorough microscopic examination of excised tissue remains the unique part of Mohs micrographic surgery.

Common Skin Cancer Treatments

When detected early, most skin cancers can be managed by more routine procedures, such as:

Curettage and electrodesiccation  -- a treatment in which the cancerous tumor and its extensions are removed by scraping (curettage) and burning (electrodesiccation).  Only part of the diseased tissue is visible to the surgeon; the invisible cancerous tissue is identified by its softness in contrast to the firm, gritty texture of normal tissue.

This treatment is most successful in the removal of superficial tumors. Recurrence rates are higher when the tumor is in scar tissue or extends into fat. With this destructive method, no tissue is available for pathological examination.

Cryosurgery -- a method of treatment in which liquid nitrogen is sprayed on diseased tissue and the surrounding area. The nitrogen causes the temperature of the tumor and surrounding healthy tissue to drop to -30 degrees to -50 degrees centigrade.  The intracellular ice crystals that form at this temperature kill the tumor cells.  The dead tissue then sloughs off, allowing the wound to heal.  As with curretage and electrodesiccation, tissue is not available for pathological examination.

Radiation therapy – a treatment that is used to destroy the cancer and its microscopic extensions by using x-rays to destroy the cancer cells.  This destructive treatment method, like the preceding ones, provides no specimen for pathological examination.

Standard surgical excision -- a treatment involving the excision of diseased tissue along with a margin of normal skin to include any microscopic extensions of the tumor.  Following surgery, a specimen is sent to a laboratory where a pathologist examines the removed tissue. If the excision is inadequate, subsequent surgeries followed by separate laboratory analysis may be required.   In a routine pathology lab, only a small percentage of the removed tissue is evaluated.  If cancer cells are present in unexamined sections, they will be missed and the cancer can recur. 

Treatment Issues

Common treatment procedures often prove ineffective because they rely on the human eye to determine the extent of the cancer.  In an effort to preserve healthy tissue, too little tissue may be removed, resulting in recurrence of the cancer.  If the surgeon is too aggressive, more healthy tissue than necessary may be removed, resulting in excessive scarring or disfigurement. 

Some tumors often do not respond well to common treatments, including those tumors greater than two centimeters in diameter, those in difficult locations and those complicated by prior treatment. Removing a recurrent skin cancer is more complicated because scar tissue makes it difficult to differentiate between cancerous and healthy tissue.  In these cases Mohs surgery is often appropriate.

Procedure

The Mohs process includes a specific sequence of surgery and pathological investigation.  Mohs surgeons examine the removed tissue for evidence of cancer cells.  Once the visible tumor is removed, Mohs surgeons trace the paths of the tumor using two key tools:

·        a map of the surgical site

·        a microscope.

Once the obvious tumor is removed, Mohs surgeons:

·        remove an additional, thin layer of tissue from the tumor site;

·        create a “map” or drawing of the removed tissue to be used as a guide to the precise location of any remaining cancer cells;

·        microscopically examine the removed tissue thoroughly to check for evidence of remaining cancer cells.

If any of the sections contain cancer cells, Mohs surgeons:

·        return to the specific area of residual tumor as indicated by the map

·        remove another thin layer of tissue only from the specific area where cancer cells were detected

·        microscopically examine the newly removed tissue for additional cancer cells

If microscopic analysis still shows evidence of disease, the process continues, layer –by layer, until the cancer is completely gone.

Indications

Mohs micrographic surgery is used primarily to treat basal and squamous cell carcinomas, but can also be used to treat less common tumors, including melanoma.  Mohs surgery is indicated when:

·        the cancer is in a difficult area where it is important to preserve healthy tissue for maximum functional and cosmetic result, such as eyelids, nose, ears, lips

·        the cancer was treated previously and recurred

·        the cancer is large

·        the edges of the cancer cannot be clearly defined

·        the cancer grows rapidly or uncontrollably

·        scar tissue exists in the area of the cancer

Reconstruction

The best method of managing the wound resulting from surgery is determined after the cancer is completely removed. Once the final defect is known, management is individualized to achieve the best results and to preserve functional capabilities and maximize aesthetics.  The Mohs surgeon is also trained in reconstructive procedures and usually will perform the reconstructive procedure necessary to repair the wound.  A small wound may be allowed to heal on its own, or the wound may be closed with stitches, a skin graft or a flap. On some occasions another surgical specialist may complete the reconstruction as part of a team approach.

Cost Effectiveness

In addition to its high cure rate, Mohs micrographic surgery also has been shown to be cost effective.  In a study of costs of various types of skin cancer removal, the Mohs process was found to be comparable to the cost of other procedures, such as electrodesiccation and curettage, cryosurgery, excision or radiation therapy.

In addition, Mohs micrographic surgery has other advantages: 

·        Because it preserves the maximum amount of normal skin, Mohs surgery often results in smaller scars.

·        With its high cure rate, Mohs surgery minimizes the risk of recurrence and eliminates the need for more complicated surgery, which may be necessary if the cancer recurs. 

·        Because the Mohs procedure is performed in the surgeon’s office and pathological examinations are conducted immediately, the entire process can often be completed in a single day.

The Mohs Surgeon

The surgeons that perform Mohs micrographic surgery are specially trained dermatologists and physicians who also serve as pathologists and reconstructive surgeons. 

The American College of Mohs Micrographic Surgery and Cutaneous Oncology (Mohs College) is the oldest professional organization of physicians who attained extensive training and experience in Mohs micrographic surgery.  The organization was founded by Dr. Frederic Mohs in 1967.  One of the major goals of the Mohs College is to ensure the highest quality of training in Mohs surgery and thereby ensure the highest quality of care for patients undergoing this procedure.

To be accepted as members of the Mohs College, physicians must complete a three-year residency in dermatology or a related field, plus a one- or two-year fellowship program approved by the Mohs College that includes extensive training in pathology and reconstructive surgery.  Currently more than 60 training centers around the United States are recognized by the Mohs College for instruction in Mohs micrographic surgery. 

Physicians who have completed a Mohs College approved fellowship will, by virtue of their rigorous training, possess the skills and expertise necessary to perform Mohs micrographic surgery at all levels of complexity.

Fort Bend Skin Cancer Center
(281) 980-6647
 Created and maintained by WSI © 2007 Privacy Policy