A prospective study of the accuracy of the surgeon's diagnosis and significance of positive margins in nonmelanoma skin cancers

Even with a precise preoperative diagnosis, complete excision of nonmelanom a skin cancer is not always achieved. The conundrum remains the decision fo r appropriate secondary treatment, Many surgeons, regardless of the nature of the lesion, consider re-excision to be the only option. In a prior 4-yea r prospective study that ascertained the accuracy of our clinical diagnosis of skin lesions removed in an office setting, one-fifth were found to be m alignant and 98 percent (n = 415) of the lesions were nonmelanoma skin canc er. Unfortunately, 65 (15.7 percent) of the malignant nonmelanoma skin canc er lesions had positive margins. The outcome of our management for these sp ecific lesions was followed prospectively over the 7.5 years of this study to determine whether aggressive surgical intervention was justified in ever y case. Of 65 patients with lesions, early and complete reexcision of margin-positi ve nonmelanoma skin cancer was performed for 34 (52.3 percent), with residu al tumor found in 11 (32.4 percent), followed by a later recurrence in one (2.9 percent). The remaining 31 patients agreed to semiannual office visits , with one (3.2 percent) recurrence in this group. Thus, the overall rate o f recurrence for margin-positive nonmelanoma skin cancer was 3.1 percent, w ith a mean follow-up of 3.6 years (range, 0 to 7.5 years). There were no recurrences for basal cell carcinoma in either treatment grou p, suggesting that, at least for "simple" primary lesions without confoundi ng risk factors, there is some validity to a "wait and see" attitude, in wh ich treatment of a potential recurrence would be straightforward. Despite o ur observed infrequent local recurrences of squamous cell cancers (13.3 per cent), the small risk of metastases still suggests the appropriateness of c omplete surgical eradication for these tumors whenever feasible.