In most cases, risks of Mohs surgery are relatively minor, but risks increase as the area treated becomes larger. Excision of smaller cancerous areas with Mohs surgery carries little risk; excising a larger area automatically carries a larger risk.
Routine Mohs Surgery
Most Mohs surgery is performed as an outpatient procedure in a doctor's office, using local anesthesia. Because Mohs surgery is so precise, removing only areas of tissue that contain cancerous cells, it often results in smaller treatment areas and reduced scarring. The risk of scarring still exists, as does the risk of infection. Other risks common to surgery, such as reactions to general anesthetic, are normally bypassed with Mohs surgery, since general anesthetic is usually unnecessary.
More Complex Mohs Surgery
Unfortunately, areas carrying cancerous cells are not always small. In some cases, Mohs surgery is used to remove larger growths that have sent cancerous growth deeper under the skin. In these cases, incisions will be larger, scarring is more likely to be severe, and the risk of infection will also be greater. Sometimes Mohs surgery requires extensive reconstruction, involving general anesthesia and increasing the risks of infection, bleeding, inflammation and extensive scarring. In cases where scarring is severe or highly visible, additional cosmetic procedures may be necessary to reduce their appearance.
The main risk involved with Mohs surgery, as with any cancer-related surgery, is that of recurrence. The chances of recurrence in the same place (that was previously treated) is slightly less with Mohs surgery than with other approaches, but a high percentage of those who experience one case of skin cancer will see additional lesions within a few years.