Commentary: Is Mohs Surgery Being Utilized Appropriately?

April 1, 2008

I was asked recently by a colleague as to when I thought she should refer patients with non-melanoma skin cancer (NMSC) for Mohs surgery? Admitting first off that I was not unbiased in this regard, since I am a fellowship-trained Mohs surgeon and practice Mohs surgery on an almost daily basis to generate part of my salary, provide revenue in support of various departmental functions and utilize the Mohs patients to provide part of the surgical training for my residents.

Key Points

A colleague recently asked me when I thought she should refer patients with nonmelanoma skin cancer (NMSC) for Mohs surgery. Admittedly, I was not unbiased in this regard, since I am a fellowship-trained Mohs surgeon and practice Mohs surgery on an almost daily basis to generate part of my salary, provide revenue in support of various departmental functions and utilize the Mohs patients to provide part of the surgical training for my residents.

However, my almost automatic answer was to suggest referring any large, complex or recurrent NMSC; those NMSC found in difficult areas to treat, such as the ear, eyelid and certain parts of the nose; those with poorly defined margins; those that show rapid growth; those histologically aggressive basal cell carcinomas, such as infiltrative, sclerosing and micronodular types; squamous cell carcinomas on the lip; patients with immunosuppression from organ transplantation or on active chemotherapy for unrelated internal malignancy; and lesions in anatomic locations where preservation of healthy, normal tissue is a priority for minimizing functional impairment or for minimizing the cosmetic deformity.

I have always believed that not every NMSC needs to be treated with Mohs surgery. I will also admit that I still use excisional surgery frequently to treat NMSCs, even on the face, and that I also still use a curet and electrosurgery to treat some skin cancers, and I feel that I am providing the proper service to every patient.

I honestly believe that opinion is in the minority, but it is still a valid argument. This dichotomy led me to do a lot of thinking about the utilization of Mohs surgery, and I learned a number of interesting facts.

The first fact I learned is that not everyone understands the true definition of Mohs surgery, other than it is the most highly effective technique in the treatment of NMSCs, with cure rates approaching 99 percent in primary (untreated) skin cancers and 95 percent for recurrent skin cancers.

However, it goes far beyond that simple fact. Mohs surgery requires that the physician act not only as the surgeon, but also as the pathologist. The tissues are processed using frozen sections prepared by trained technicians under the direct supervision of the Mohs surgeon. It is improper to have the tissues interpreted by someone other than the Mohs surgery and bill using the Mohs surgery codes.

Pathologists in virtually every hospital-based clinical laboratory interpret frozen sections on a daily basis. However, it isn't Mohs surgery, and those billing codes should not be used.

Despite these facts, there is no board certification in Mohs surgery, and also no training requirements that must be satisfied in order to bill for performing it.

So, who is doing Mohs surgery? Upon investigation, I learned that 97.9 percent of all Mohs surgery, using data from insurance company codes, is performed by dermatologists.

The last complete year for which data is available showed that of the approximate 8,400 practicing dermatologists in the United States, 2,020 (or 24 percent), utilized Mohs surgery billing codes.

This is reflected in a growth from 8 percent of Medicare patients having Mohs surgery in 2002 to 20 percent having Mohs surgery in 2007. While this increase is substantial, it still represents only one in five skin cancers treated with Mohs surgery in Medicare patients.

So, the real question should be: Is the proper percentage of Medicare patients receiving treatment of their NMSC with Mohs surgery?

The answer to that question is very complex, because the criteria for utilizing Mohs surgery have not been codified.

It is also important to recognize that NMSCs are the most common of all cancers, and the rates are rising to almost epidemic levels.

It has been estimated that in the 10 years from 1995 to 2005, there has been a 38 percent increase in NMSC in the United States. Furthermore, the incidence of skin cancer in Medicare patients is projected to rise another 32 percent by 2010.

So, does this increase in Mohs surgery utilization represent abuse of the system, or, rather, an appropriate application of this technique in the face of an epidemic increase in skin cancer due to the rapidly growing number of "baby boomers" reaching the age when NMSCs are expected to increase?

The answer is unknown, but perhaps it is possible to get some idea of any potential for over-utilization by looking at the other forms of skin cancer treatment for similar signs of increased utilization.

During the 10-year period from 1995 to 2005, the destructive codes for treating skin cancer increased by 57 percent, and the excision codes for treating skin cancer increased by 16 percent. However, during that same period, the Mohs surgery codes increased by 312 percent!