Costs and Economics of Skin Cancer Management, Mohs Surgery, and Surgical Reconstruction
First, the authors refer to a statistic that Mohs micrographic surgery (MMS) utilization increased by 700% between 1992 and 2009. The source of this number remains obscure. One opinion piece in the dermatology literature mentions this statistic,2 though the article cited as this number’s source does not include this calculation.3 Although a 7-fold increase in utilization of MMS would not in itself be problematic over this time period (MMS training only became widespread in the early 1980s and the incidence of NMSC skyrocketed), the accuracy of this statistic remains unclear.
Second, when considering the global cost of NMSC care, it is important to recall that a significant proportion (up to 30%, based on some studies)4 of MMS cases are allowed to heal by secondary intention, whereas excisions are almost always closed primarily. The significant cost of posttumor extirpation repair, which may be several times the excision cost, was not addressed by the authors.
Third, the authors do not account for the impact of the multiple procedure reduction rule on cost. Medicare and almost every private insurer reduces payment for the secondary (less expensive) procedure by 50%; because MMS bundles the cost of the excision and pathology together, it is (unless a flap or graft is used) more costly than the repair, and thus repair reimbursements associated with MMS are halved. In contrast, repairs after excisions are usually reimbursed at 100%, and the (more modest) excision reimbursement is halved. Importantly, pathology fees are reimbursed at 100% when MMS is not used. These changes together have a net negative effect on the cost of MMS care.
Fourth, the authors cite 2 studies5,6 regarding recurrence rates and suggest that recurrence rates after MMS and excision are “the same.” In fact, these studies found that post-MMS recurrence rates are lower (the authors swapped the percentages of the first study in their article and the numbers for the second do not match the cited article), though not statistically significantly so. It is not clear, moreover, whether these studies were sufficiently powered to detect a significant difference in recurrence rates. Both of the cited studies were controversial and had significant methodological shortcomings, including generalizability, bias, and confounding.7–11 Most importantly, the first study was a trial where MMS was not compared with a single excision but rather to a set of serial excisions performed to obtain clear margins, whereas the latter was a cohort study in which patients were not randomized at all. A large meta-analysis of available studies suggested that the recurrence rate for primary basal cell carcinoma, for example, is 10.1%, more than 5 times the recurrence rate seen with MMS in the studies cited by the authors.12
Fifth, the authors note that on average “1 in 4 cases of skin cancer is treated with MMS.” If correct, this points to a dramatic underutilization of MMS in the United States because based on the Appropriate Use Criteria 1 academic center suggested that 72% of tumors would be MMS eligible.13 Although surgeons should be responsible stewards of the healthcare system, it is not clear whether self-imposed rationing is desirable or indeed ethical.14
Sixth, the authors refer to “margins” as a measure of the size of the excised tumors; these numbers, based on current procedural terminology coding, are based on total lesion size including margins, not simply the margins around the tumor.