Variables Affecting Basal Cell Carcinoma and Melanoma In Situ Excision Clearance: A Multi-institutional Retrospective Study.

BACKGROUND The primary endpoint for surgical excision of skin cancer is the positive margin status. Tumor characteristics may explain much of this risk, but other important factors can include physician specialty. OBJECTIVE To determine the variables affecting the success of a basal cell carcinoma (BCC) or melanoma in situ (MIS) excision. METHODS/MATERIALS An 8-year, multicenter, retrospective study of 5,800 BCC or MIS excisions performed at 13 different Kaiser Permanente medical centers. The margin status was determined by searching final pathology diagnosis texts for phrases associated with positive margins. RESULTS An incomplete excision rate was found in 23% of all specimens (BCC-22%, MIS-25%). Per specialty, the proportion of specimens with positive tumor margins was 24% for dermatology, 26% for plastic surgery, 28% for otolaryngology, and 12% for general surgery. General surgeons most often excised large tumors and tumors from truncal regions, 2 variables conferring lower odds of an incomplete excision. For non-Mohs procedures, dermatologists were no different than otolaryngologists or plastic surgeons in performing an incomplete BCC or MIS excision in all multivariate models (all p > .05). CONCLUSION Intrinsic tumor characteristics may influence the success of achieving tumor-free resection margins more than the specialty of the provider.