Outcomes of Patients With Multiple Cutaneous Squamous Cell Carcinomas: A 10-Year Single-Institution Cohort Study.

IMPORTANCE: Patients with multiple cutaneous squamous cell carcinomas (CSCCs) pose a management challenge for physicians, but their prognosis is unknown because outcomes have not been compared between patients who form single vs multiple CSCCs. OBJECTIVE: To compare outcomes in patients with 1 vs multiple CSCCs. DESIGN, SETTING, AND PARTICIPANTS: A 10-year retrospective single-institution cohort study at an academic tertiary care center of patients with dermally invasive (non-in situ) primary CSCC diagnosed from January 1, 2000, through December 31, 2009. MAIN OUTCOMES AND MEASURES: Electronic medical records were reviewed to determine the tumor stage (Brigham and Women's Hospital tumor stage) and outcomes (local recurrence [LR], nodal metastases [NM], and death due to CSCC). Outcomes were compared between patients with 1 vs more than 1 CSCC via multivariable competing-risk regression adjusted for other significant cofactors. RESULTS: Of 985 patients with CSCC, 727 had 1 CSCC, 239 had 2 to 9 CSCCs, and 19 had 10 or more CSCCs. Most patients with 10 or more CSCCs were immunosuppressed (15 of 19 [78.9%]). The median follow-up time was 50 months (range, 2-142 months). Patients with more than 1 CSCC had a higher risk of LR (subhazard ratio for 2-9 CSCCs, 1.8; 95% CI, 1.1-4.3; and for ≥10 CSCCs, 3.8; 95% CI, 1.4-10.0) and NM (subhazard ratio for 2-9 CSCCs, 3.0; 95% CI, 1.4-6.5; and for ≥10 CSCCs, 4.2; 95% CI, 1.4-10.4) compared with patients with 1 CSCC, adjusted for Brigham and Women's Hospital tumor stage. The 10-year cumulative incidence of LR and NM was higher in patients with 2 to 9 CSCCs and markedly higher in those with 10 or more CSCCs compared with patients who had 1 CSCC (10-year cumulative incidence for 1 CSCC: LR, 3.0%; 95% CI, 2.0%-4.5%; and NM, 2.3%; 95% CI, 1.5%-3.8%; for 2-9 CSCCs: LR, 6.7%; 95% CI, 4.2%-10.6%; and NM, 5.9%; 95% CI, 3.5%-9.6%; and for ≥10 CSCCs: LR, 36.8%; 95% CI, 19.2%-59.0%; and NM, 26.3%; 95% CI, 11.8%-48.8%). CONCLUSIONS AND RELEVANCE: Patients with multiple CSCCs warrant frequent follow-up because they have an elevated risk of LR and NM. In particular, patients with 10 or more CSCCs have markedly elevated risks of recurrence and metastasis.