Because recurrent NMSCs are more difficult to treat and more likely to recur than primary tumors, many experts have recommended that Mohs be the treatment of choice for recurrent tumors, 6,7
and we predicted that therapy selection would be similar at different sites. Instead, we found substantial and consistent differences in the treatment of recurrent NMSC at 2 affiliated academic clinics. Recurrent tumors treated at the university site were significantly more likely to receive Mohs than those at the VA site even after adjusting for many patient, tumor, and physician characteristics that might influence treatment (P
Our data do not fully explain this finding. Patients at the 2 sites differed markedly, and unmeasured patient characteristics may have contributed to the variation in therapy. For example, patient preferences may have been important in affecting treatment choice. Patients at one site may have believed that therapies differ in costs, benefits, and/or effects on many health outcomes and may have requested one of the therapies based on these beliefs. We did not measure patient preferences or the extent to which clinicians included patient preferences in their treatment choices. Thus, we do not know whether university and VAMC patients differed systematically in their preferences for treatments and whether any differences may have contributed to the variation in treatments. Similarly, although the multivariate models adjusted for a variety of potentially important tumor features, unmeasured tumor characteristics may also have contributed to the variation in treatment.
Clinicians at the 2 sites had different incentives to choose different therapies, which may have contributed to the variation in care. More clinical encounters at the university site than at the VAMC were reimbursed on a fee-for-service basis, but clinicians at both sites were salaried, so their incomes were not directly related to their treatment choices. Moreover, for most tumors, the diagnosing and treating clinicians were different, so that treatment decisions were not made by the clinician who ultimately performed the procedure. Thus, direct financial incentives seem unlikely to have accounted for the difference. Some of the patients seen at the university site may have been referred to the practice for diagnosis and therapy, and there may have been an expectation by the patient or referring physician that Mohs was to be performed. Finally, residents (who treated proportionately more tumors at the VAMC site than at the university site) may have had educational incentives to recommend excision (which they could perform, and thus obtain experience with the procedure).
Finally, we do not have a specific measure of access to care at the 2 sites. On the one hand, all therapies were available at both sites, and the fact that there was no difference in median time interval between biopsy and Mohs at the 2 sites does not suggest that Mohs was less available at the VAMC. On the other hand, even though the 2 sites had similar time intervals to treatment, the university site had 2 Mohs surgeons, whereas the VA had only 1 part-time Mohs surgeon. In addition, a third Mohs surgeon was recruited to the university site soon after the study period to improve the availability of Mohs at this site. Thus, there may have been reduced access to Mohs at the VAMC in a practical sense because of the striking difference in clinician availability at the 2 sites, which may have resulted in fewer attempted referrals for Mohs at the VAMC.
These and other potential limitations to this study are listed in . The study was limited to 1 city and 1 academic program, which may not be typical of other locations. Also, the sample size is relatively small, which limited the adjustments that could be made in the multivariate analyses. The major finding is consistent in multiple clinically important subgroups, however, suggesting that the basis for the difference in care is probably not entirely clinical and may be related to systematic differences in patient preferences, educational incentives, or availability of Mohs.
Potential Limitations of the Study
We have no evidence that the quality of care varied at the 2 sites. Regardless of the explanation for the variation in care, these data further highlight a lack of consensus about a single preferred treatment for recurrent NMSC2
and the fact that rigorous data do not exist to inform such a consensus. Early results of a recent randomized trial10
for recurrent basal cell carcinomas on the face demonstrated no statistically significant difference in tumor recurrence at 18 months after excision or Mohs. These findings have been controversial,11
however, and are too preliminary to change practice guidelines. Mohs was the more costly therapy in that European study,10
which illustrates that determining the comparative effectiveness of the treatments is important. Overall, our findings emphasize that the care of this highly prevalent condition of older patients warrants increased scrutiny. Determining optimal treatment for these tumors will require a longitudinal study of outcomes of different therapies to provide a basis for formal treatment guidelines that can be adopted more broadly.