Conversion-intent PD-1-based chemoimmunotherapy restores surgical feasibility in borderline resectable or unresectable non-head-and-neck cutaneous squamous cell carcinoma

BACKGROUND: The perioperative role of systemic therapy remains poorly defined in borderline resectable or unresectable non-head-and-neck locally advanced cutaneous squamous cell carcinoma (cSCC). We evaluated whether conversion-intent PD-1-based chemoimmunotherapy could restore surgical feasibility in this setting. METHODS: This single-center retrospective cohort study included consecutive patients with non-head-and-neck locally advanced cSCC treated with conversion-intent PD-1 inhibitor plus taxane/platinum-based chemotherapy between January 2022 and December 2025. The primary endpoint was conversion to surgical candidacy. Secondary endpoints included surgery, R0 resection, radiologic and pathologic responses, safety, and survival outcomes. RESULTS: Among the 28 included patients, 17 (60.7%) had unresectable disease at baseline. Following conversion-intent systemic therapy, 23 patients (82.1%) were considered eligible for surgery, and 22 (78.6%) underwent curative-intent surgery. R0 resection was achieved in 16 patients overall (57.1%) and in 72.7% of patients who underwent surgery. The objective response rate was 50.0%, the disease control rate was 89.3%, and the radiologic downstaging rate was 46.4%. Primary-site pathological complete response was observed in 18.2% of patients who underwent surgery. Treatment-related adverse events were common (85.7%), whereas grade ≥3 events were infrequent (14.3%), and permanent discontinuation and surgery delay each affected only a small minority of patients. CONCLUSION: Conversion-intent PD-1-based chemoimmunotherapy was associated with restoration of surgical feasibility in selected patients with borderline resectable or unresectable non-head-and-neck locally advanced cSCC. These findings support a conversion-oriented treatment approach and suggest that surgery-related endpoints may be more informative than radiologic response alone in this setting.