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Predicting Subclinical Spread in Nonmelanoma Skin Cancer

Variables of size and location can predict subclinical spread and identify tumors suitable for Mohs micrographic surgery.

Mohs micrographic surgery (MMS) is indicated for tumors with a high risk for recurrence, and tumors with substantial subclinical spread are ideal candidates for such an approach. These investigators sought to identify risk factors predictive of extensive subclinical spread in nonmelanoma skin cancer. They used univariate and multivariate statistical analyses to examine data on 1095 patients with nonmelanoma skin cancer treated with MMS during a 3-year period.

A 3-mm margin was included at each MMS stage. The 22% of tumors that required 3 or more stages to achieve a tumor-free plane were classified as having extensive subclinical spread and were compared with the remaining 78% of tumors. Univariate analysis identified location on the nose, ear, eyelid, temple, or neck; size larger than 1 cm; and having morpheaform basal cell carcinoma (BCC), recurring BCC, or squamous cell carcinoma as factors associated with high risk for extensive subclinical spread. In the multivariate analysis, larger preoperative size; any BCC on the nose; morpheaform BCC on the cheek; recurrent BCC in men; neck tumors in men; and locations on the ear helix, eyelid, or temple were associated with extensive subclinical spread. Interestingly, age younger than 35 was a significant "protective" factor, and immunosuppression was not associated with the extent of spread.

Comment: This research adds size greater than 1 cm (rather than 2 cm) and location on the neck to the list of risk factors that indicate a benefit from MMS. As the control patients (whose tumors required fewer than 3 stages) had already been preselected for MMS, some features (e.g., immunosuppression) were probably present in both groups and were not significantly more common in patients with extensive spread. Presumably the patients younger than 35 had significantly less subclinical spread because they were diagnosed and treated while their tumors were still small. In the younger group, tissue sparing rather than a higher cure rate is the primary benefit of MMS.

— George J. Hruza, MD

Published in Journal Watch Dermatology August 28, 2002

Citation(s):

Batra RS and Kelley LC. Predictors of extensive subclinical spread in nonmelanoma skin cancer treated with Mohs micrographic surgery. Arch Dermatol 2002 Aug; 138:1043-51.

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