Although adjuvant radiotherapy (ART) is advised for some high-risk cutaneous squamous cell carcinomas after clean margin surgery, there is a dearth of evidence demonstrating its usefulness. For a study, researchers sought to assess the effects of ART on treatment outcomes for high T-stage cutaneous squamous cell carcinomas after clear margin resection.

An analysis of high T-stage cutaneous squamous cell carcinomas (Brigham and Women’s Hospital T2b or T3) with negative histologic margins following excision during a 20-year period at two academic locations. Depending on whether tumors got ART or were left untreated, local recurrence (LR) and locoregional recurrence (LRR) were compared. 

There were 508 tumours altogether, 96 of which received ART (ART+). ART+ had a lower 5-year cumulative incidence of LR (ART+, 3.6% [95% CI, 1.6%-7.7%] vs ART, 8.7% [95% CI, 6.3%-12.0%]) and LRR (ART+, 7.5% [95% CI, 4.4%-11.9%] vs ART, 15.3% [95% CI, 11.9%-22.1%]). Due to a greater 5-year cumulative incidence of LRR, recurrent tumours greater or equal to 6 cm or Brigham and Women’s Hospital T3 tumours were classed as high-risk (High-risk, 26.3% [95% CI, 19.0% -35.7%]). A reduced 5-year cumulative incidence of LRR was seen in high-risk tumours treated with ART (ART+, 17.2% [95% CI, 11.9% -26.4%] vs ART, 31.0% [95% CI, 26.1%-40.8%]).

The probability of LR and LRR was lowered in half when clean margin surgery was performed after ART for high T-stage cutaneous squamous cell carcinomas.