Commentary on Recurrence and Mortality of Melanoma in Situ of the Trunk or Extremities.

Strong opinions are the cacti that flourish in data desserts. Accordingly, the controversy regarding the appropriate use of Mohs micrographic surgery (MMS) for treatment of melanoma is due to significant challenges in obtaining convincing data. These challenges include defining outcomes such as local recurrence, the variation in MMS technique that make generalization of single institution experience difficult, the ethical implications of randomizationwhen surgeonsmay not have clinical equipoise, and the heterogeneity of institutional policies regarding melanoma treatment that preclude multicenter studies. In this issue of Dermatologic Surgery, a study by Daniel and colleagues attempts to approach these challenges with a retrospective database study to address the data drought. There is currently no consensus on which outcomes should be used to measure MMS against standard excision. An explosion of the recent literature suggests there may be significant benefit in usingMMS for melanoma in situ (MIS) in high-risk sites as measured by recurrence rates, cost, and patient preference. There is also evidence that there might be advantages in usingMMS for invasive disease. These studies have made clear that there is a role for MMS in melanoma treatment but leave open the question of when MMS is clinically superior and resource efficient. For which tumors and which patients are MMS superior to local excision, and howdowemeasure superiority? Which tumors are too advanced to benefit from MMS and which too low risk to benefit fromMMS? These questions are much harder to answer but as is often the case, more worthwhile. Clinically relevant outcomes are critical in answering these questions, and they must be matched to the appropriate patient population. For example, mortality and disease free survival are important outcomes for invasive melanoma, whereas local recurrence, patient preference, cosmesis, and cost may be better at distinguishing surgical modalities for in situ disease. Anatomical location, age, and other patient factors may also be important to consider. A national consensus onwhich outcomes aremost important andwhere data gaps exist would inform the design of studies that can influence guidelines. Daniel and colleagues use the Surveillance, Epidemiology, and End Results (SEER) database to compare MMS with local excision forMIS on the trunk and extremities. No clinically significant differences in 5-year overall mortality, disease-specific mortality, or local recurrence were detected. The generalizability of this study is its primary strength. The use of a large, nationally representative cohort avoids biases of previous single institution studies. Like many database studies, however, the study by Daniel and colleagues is limited by potential baseline differences in the treatment groups, vagaries in the definition of local recurrence, and a low event rate that could obscure a true difference. Despite these caveats the study presents new data with a statistically valid analysis. Mohs micrographic surgery can deliver tremendous value to patients and society by improving cure rates, enhancing the patient experience, and reducing overall costs. These benefits have been clearly demonstrated for melanoma in high-risk sites but remain unproven for melanoma in lowrisk sites. Daniel and colleagues have demonstrated that MMS is unlikely to reduce local recurrence or mortality for melanoma in low-risk sites which is consistent with the current AAD/ACMS/ASDSA appropriate use criteria designation of “uncertain. ” The possibility that MMS might decrease costs or improve the patient experience remains, but until further data on low risk-tumors demonstrate thatMMS provides added value in one of these dimensions, its value in this scenario will remain unclear. Mohs micrographic surgery may be a powerful technique for the treatment of melanoma, but overutilization unsupported by data could threaten its overall efficacy and acceptance. Critical evaluation of the data, such as the study published in this issue, reveals that the utility of MMS for low-risk cancers in low-risk sites remains uncertain. By limiting the use of MMS when its value is unclear, we will be upholding the high standards forwhichdermatologic surgery is known. Our patients and colleagues expect no less.