Mohs micrographic surgery is a refinement of an innovation in 1936 by Dr. Frederick Mohs. It is a highly specialized outpatient surgery that offers the best cure rate for many skin cancers, while maximally sparing healthy tissue. The distinctions of this procedure are many and include:
- Margin Control
Mohs surgery uniquely orients, maps, and processes removed tissue, which permits the microscopic evaluation of virtually 100% of the specimen margins. The completeness of this margin control permits the accurate identification and removal of all tumor extensions under the microscope. Tissues in Mohs surgery are processed as modified frozen sections, which allows the accurate and rapid interpretation of most skin cancers.
- Cure Rate
With complete margin control, Mohs surgery may achieve the highest cure rate for many skin cancers. For primary (cancers that have not been treated previously) basal cell cancers (BCC) and squamous cell cancers (SCC), Mohs surgery cure rates are 99% and 97%, respectively. For recurrent (cancers that have returned from previous therapy) BCC and SCC, Mohs surgery cure rates are 94% and 90%, respectively. These cure rates are higher than other conventional options.
- Tissue Sparing
The preciseness of the Mohs process allows the Mohs surgeon to remove cancer growths one layer at a time, while maximally preserving healthy tissue. For the patient, the least tissue removed potentially translates into the smallest wound possible and hence the smallest scar possible.
- Outpatient Procedure
Mohs surgery is performed under local anesthesia and occasionally with mild sedation. Patients may avoid general anesthesia, return home immediately and have a rapid recovery. This can be a significant benefit for older patients, who are also the ones most susceptible to skin cancers.
The meticulous nature of Mohs surgery is time intensive, so it is more expensive than routine excision methods. In many cases, the Mohs surgeon repairs the wound on the same day or the next day, but sometime consultation with additional specialists is sought for difficult cases. Depending on the cancer, one tumor may require several hours to an entire day to clear and repair. Some cancers are not accurately seen with the frozen sections in Mohs surgery. Finally, cancers that have already spread to lymph glands or elsewhere are not treatable with this technique.
When is Mohs surgery needed?
Despite its many advantages, Mohs surgery should not be applied for every skin cancer. Mohs micrographic surgery is best indicated for skin cancers that are at higher risk for tissue destruction, recurrence, or metastasis. These high-risk features include:
Skin cancers on the head and neck, especially on or near the temple, ears, eyes, nose, mouth and lips. These sites are cosmetically and functionally important and maximally preserving healthy tissue becomes critical. Further, skin cancers in these areas may be more aggressive. Other non-facial locations, such as the genitalia, hands and feet, and fingers and toes may also be considered for Mohs surgery. to achieve high cure rate and maximally spare healthy tissue.
Tumors that return from previous treatment are at higher risk. Generally, they are more difficult to cure, behave more aggressively, and destroy more tissue. Mohs surgery is ideal for many recurrent skin cancers and achieves the highest cure rate.
Cancers greater than 2 centimeters (7/8 inch) are more difficult to treat and may be more aggressive.
The initial biopsy may reveal high-risk features such as infiltrative, morpheaform/sclerosing, micronodular, deeply invasive, spindle cell, perineural, poorly differentiated, etc. Mohs surgery may achieve an excellent cure rate for these higher risk skin cancers.
- High-Risk Patients
Patients who have certain genetic conditions (Basal cell nevus syndrome, albinism, etc.) or who are immunosuppressed (organ transplant recipients, HIV/AIDS, leukemia/lymphoma, etc.) may develop not only more skin cancers, but also more aggressive skin cancers. Mohs surgery should be an integral part of therapy for skin cancers in these patients.