Patients who receive Mohs micrographic surgery fare better at academic/top volume facilities, retrospective analysis suggests

Where a patient with early melanoma gets treated appeared to affect prognosis, a retrospective analysis suggested, as those who received Mohs micrographic surgery (MMS) at either an academic or a top volume facility had better long-term survival outcomes than those who had the same procedure done at a nonacademic or a low volume facility.

In a cohort of 4062 patients with nonmetastatic, T1a-T2a melanoma, those who underwent surgery at an academic facility had a nearly 30% lower risk of death at a hazard ratio (HR) of 0.73 (95% CI, 0.59-0.89) compared to patients who underwent surgery at a nonacademic facility, senior author Michael Girardi, MD, Yale University School of Medicine, New Haven, Connecticut, and colleagues reported in JAMA Dermatology.

Similarly, treatment at a top decile-volume facility (TDVF) was associated with a 21% improvement in overall survival (OS) at a HR of 0.79 (95% CI, 6.4-0.97) compared with a low volume facility. “To our knowledge, this is the first evidence of the role of facility-level factors in influencing patient outcomes after MMS for invasive melanoma,” Girardi and colleagues observed. “These results have implications for furthering the understanding of associations between facility-level characteristics and cancer outcomes as a whole as well as for the continued use of MMS for invasive melanoma.”

Patients diagnosed with early melanoma and who went on to be treated with MMS were identified in the National Cancer Database (NCDB), which is a nationwide resource data set that includes roughly 70% of all newly diagnosed cancers in the US. The median age of patients was 60 years, over 96% of them were non-Hispanic White and 92% had no comorbidities.

“The most common tumor primary site was on the head and neck…followed by the extremities…and the trunk,” the authors wrote. Over three-quarters of the tumors were under 0.8 mm and over 78% of patients had node-negative disease.

“Patients were treated at a total of 462 facilities,” researchers pointed out, 27.5% of which were identified as academic institutions where 56.8% of patients were actually treated. Some 13.4% of the facilities were identified as TDVFs, where 61.9% of patients were treated. However, some 60% of the TDVFs were academic institutions as well.

The median annual case volume was 3.71 (interquartile range (IQR), 2-9.8 cases) at academic centers compared with a median of 1.75 (IQR, 1.2-2.9 cases) at nonacademic centers. Among low volume centers, the median annual case volume was 1.8 (IQR, 1.3-3) compared with a median of 15.7 cases (IQR, 10.5-26.2) for TDVFs.

More tumors on the head and neck, 48.6%, were treated at academic centers compared with 26.9% of the melanomas treated at nonacademic centers (P<0.001). Similarly, more head and neck tumors, 47%, were treated at TDVFs than at low volume facilities where 26.4% of the tumors treated were head and neck tumors (P<0.001). Conversely, superficial spreading tumors made up a larger proportion of tumors treated at both nonacademic and low volume facilities at 37.5% and 38.5%, respectively, than those treated at academic and high-volume centers, where 28.4% of tumors treated at both types of facilities were superficial spreading tumors.

As the authors pointed out, previous analyses of different cancer types have found that high-volume and academic hospitals were more likely to following guideline recommendations for the treatment of specific cancer types, which in turn led to improved long-term survival outcomes. Importantly, they noted that MMS has not yet been included in national guidelines for the treatment of invasive melanoma. However, it’s still possible that high-volume academic centers are more likely to follow current recommendations for the use of MMS even though its use is not yet included in contemporary melanoma guidelines, they noted. There is also the possibility that differences in patient outcomes observed between the different types of facilities simply reflect the greater experience higher volume centers have in using MMS for melanoma treatment which may have resulted in better surgical technique.

Given that the use of MMS has rapidly increased for the treatment of invasive melanoma, “[t]he findings of the present study as well as the increasing use of MMS for melanoma support the development of consensus guidelines for the procedure’s use,” the study authors recommended. “Such guidelines may serve to reduce variations in practices and patient outcomes between facilities,” they speculated.

Commenting on the study, Christopher Miller, MD, University of Pennsylvania, Philadelphia, and Christopher Bichakjian, MD, University of Michigan, Ann Arbor, Michigan, suggested that findings from the study should be interpreted with caution.

“First, it is challenging to demonstrate a true survival benefit based on retrospective data among a cohort of patients with established 5-year disease-specific survival rates exceeding 95%,” they pointed out. Moreover, they suggested it was “unlikely” that the observed survival benefit for high-volume/academic centers was due solely to a surgical technique when prospective, randomized trials with surgical margins up to 5 cm have failed to demonstrate a disease-specific survival advantage.

“[T]he NCDB reports overall rather than disease-specific survival, indicating that unmeasured confounders could skew mortality rates, particularly among older patients…[and it also] does not record local recurrence rate, which is a more relevant measure of the effectiveness of melanoma surgery,” Miller and Bichakjian wrote. In addition, the NCDB is a hospital-based registry so findings may not apply to private practices in the community where in fact MMS is frequently performed for the treatment of melanoma. The editorialists also noted that over 70% of all melanomas treated with MMS at either low-volume or nonacademic facilities were not on the head and neck; for these non-head and neck tumors, MMH may not have been necessary.

“If MMS is indicated for melanomas at greater risk for recurrence after conventional WLE (wide local excision), one would expect to use MMS predominantly for specialty-site or locally recurrent/persistent melanomas,” they suggested. Miller and Bichakjian also questioned whether performing MMS at least 8 times a year for the treatment of melanoma really qualifies a facility as being high-volume, as the study authors judged it to be. And, they pointed out, the authors did not address how many cases of MMS a surgeon must have conducted to be considered competent in the treatment of melanoma; given that annual facility volumes were not that high, the majority of surgeons may not have achieved the minimum number of MMS cases as are required by the American Committee on Graduate Medical Education for its fellows to be considered competent in MMS.

“Like other technical procedures, MMS for melanoma has a steep learning curve and requires competency standards to achieve and maintain expertise,” Miller and Bichakjian wrote. “Performing 8 cases per year, in our opinion, is insufficient for a surgeon to be considered an expert.”

  1. High-volume, academic centers who treat early melanoma with Mohs micrographic surgery (MMS) had better overall survival outcomes than low-volume, non-academic centers.

  2. Facility-level factors may influence outcomes after MMS for melanoma but survival differences between facilities are difficult to demonstrate when disease-specific survival rates already exceed 95%.

Pam Harrison, Contributing Writer, BreakingMED™

Neither the authors nor the editorialists had any conflicts of interest to declare.

Cat ID: 26

Topic ID: 78,26,730,11,26,192,925