Re-excision of incompletely excised cutaneous squamous cell carcinoma: histological findings influence prognosis.

Introduction: We have previously shown 28.6% of re-excisions for margin-positive cutaneous SCC to yield residual tumour (positive re-excision). Original tumour diameter and thickness conferred significant risks for positive re-excision. We now report a 5-year prospective follow-up of our re-excision cohort.

Results: Of 676 consecutive SCC patients, 84 underwent wider-excision for positive margins. 79 of these patients completed a mean of 28 months follow-up. Overall, 9/79 (11%) of this re-excision cohort experienced locoregional recurrence, all within 2 years of primary resection. Of the positive re-excisions, 29% experienced recurrence, vs 5% in those with negative re-excisions. Logistic-regression analysis revealed positive re-excision to predict recurrence (P<0.05, RR 10.1), independent from tumour-grade, anatomical site, size, and delay to re-excision.

Conclusion: Factors associated with residual tumour on re-excision are similar to characteristics of high-risk SCCs; larger tumours in particular are more likely to persist and may benefit from wider excision-margins at original resection. Positive re-excision is newly identified as a significant risk for locoregional recurrence, whilst negative re-excision is associated with a return to a low-risk prognosis, for all tumours. Our findings thus support the treatment of cutaneous SCC through to completion. We also recommend re-excision where narrow or close margins are reported. Patients with a positive re-excision should be considered at high risk for recurrence, requiring extended follow-up.