A risk scale for predicting extensive subclinical spread of nonmelanoma skin cancer

BACKGROUND. The clinical appearance of nonmelanoma skin cancer may represent only a portion of microscopic tumor invasion. OBJECTIVE. To develop a scale based on high-risk characteristics for predicting the probability of extensive subclinical spread of nonmelanoma skin cancer. METHODS. Retrospective analysis of 1095 Mohs micrographic surgical cases (MMS) yielded high-risk factors for extensive tumor spread, defined as requirement of greater than or equal to3 MMS layers. Predictive characteristics included: any BCC on the nose, morpheaform BCC on the cheek, neck tumors and recurrent BCC in men, location on the eyelid, temple, or ear helix, and size >10 turn. Multivariate logistic regression was applied to develop a risk index. RESULTS. Tumor characteristics were assigned point values calculated from the respective odds of extension and categorized p into six risk classes with probabilities of extensive subclinical spread ranging from 10% to 56%. CONCLUSION. A risk scale simplifies and enhances prediction of extensive tumors. The associated probabilities can help to guide patient preparation and appropriate therapy.