Sentinel lymph node biopsy versus observation in high‐risk cutaneous squamous cell carcinoma in immunosuppressed and immunocompetent patients: An inverse probability of treatment weighting study

Background The survival benefit of sentinel lymph node biopsy (SLNB) in immunocompetent and immunosuppressed patients with high‐risk cutaneous squamous cell carcinoma (cSCC) has not been established. Objective To determine whether SLNB improves disease‐specific survival (DSS) in high‐risk cSCC. Secondary objectives were to analyse disease‐free survival, nodal recurrence‐free survival and overall survival (OS). Methods Multicentre, retrospective, observational cohort study comparing survival outcomes in immunosuppressed and immunocompetent patients treated with SLNB or watchful waiting. Inverse probability of treatment weighting was used to adjust for possible confounding effects. Results We studied 638 tumours in immunocompetent patients (SLNB n = 42, observation n = 596) and 173 tumours in immunosuppressed patients (SLNB n = 28, observation n = 145). Overall, SLNB was positive in 15.7% of tumours. SLNB was associated with a reduced risk of nodal recurrence (NR) (hazard ratio [HR], 0.05 [95% CI, 0.01–0.43]; p = 0.006), disease specific mortality (HR, 0.17 [95% CI, 0.04–0.72]; p = 0.016) and all‐cause mortality (HR, 0.33 [95% CI, 0.15–0.71]; p = 0.004) only in immunocompetent patients. Conclusions SLNB was associated with improvements in NR, DSS and OS in immunocompetent but not in immunosuppressed patients with high‐risk cSCC.