Squamous Cell Carcinoma of the Conjunctiva: A Population-Based Study on Epidemiologic Trends, Cancer-Specific Survival Patterns, and the Risk of Second Malignant Neoplasms, 1975 to 2016.

Purpose: To analyze the national epidemiologic trends of squamous cell carcinoma of the conjunctiva (SCCC) over 4 decades, providing the largest report on disease-specific survival (DSS) outcomes and investigating the risk of developing second primary neoplasms in these patients.

Methods: This retrospective, population-based cohort study analyzed 1,172 patients diagnosed with SCCC from January 1, 1975, through December 31, 2016. Data were extracted from the US Surveillance, Epidemiology, and End Results database. Incidence, DSS, and the relative risk (95% confidence interval) of developing second primary neoplasms were studied.

Results: SCCC incidence (0.45/million/year) increased during the study's time period (regression coefficient = 0.004, p = 0.002), primarily due to an increasing incidence in women (regression coefficient = 0.004, p = 0.003) and in White (regression coefficient = 0.006, p = 0.007) patients. The 5-year DSS was 95.4%. Sex and race did not impact survival. Patients residing in the Midwestern United States exhibited the lowest survival compared with other regions with a 5-year DSS of 85.2% (p = 0.008). White male SCCC patients are at an increased risk, compared with the general population, of developing second primary neoplasms of the liver (relative risk = 4.8 [1.3-12.4]; p < 0.05), respiratory tract (relative risk = 2.3 [1.4-3.6]; p < 0.05), and skin (relative risk = 3.7 [1.8-6.9]; p < 0.05).

Conclusions: SCCC incidence has been increasing in the United States. DSS is substantially higher than the overall survival previously reported in the literature. The area of residence significantly impacts survival. White men with SCCC are at an increased risk of developing second primary neoplasms of different organ systems.