Evaluating associations of advanced stage at diagnosis of squamous cell anal cancer by sex among adults with and without HIV in the US

Background: Although a rare malignancy, anal cancer incidence is increasing with a growing proportion diagnosed at advanced stages. Our objective was to evaluate factors associated with advanced stage-at-diagnosis (stage 3+) of squamous cell carcinoma of the anus (SCCA) among men and women with and without HIV. Methods: We analyzed U.S. National Cancer Database data (2004-2020) for patients aged 18-89 years with SCCA (ICD-O-3: C210-C218). The outcome was advanced stage at diagnosis (stage 3/4). Stratified by sex, we assessed associations with demographics, HIV status, healthcare access (facility type, insurance), and geographic factors using hierarchical multivariable Poisson regression to estimate adjusted prevalence ratios (aPR) and 95% confidence intervals (CI). Results: Among 36,389 patients with SCCA, 2,600 (7.1%) were living with HIV and 42% were diagnosed at stage 3-4. Women without HIV were more likely to be diagnosed at an advanced stage compared to men without HIV (aPR: 1.20, 95% CI: 1.05-1.37). Among both sexes, NH-Black race (aPR: 1.09, 95% CI: 1.04-1.14), being uninsured (aPR: 1.31, 95% CI: 1.23-1.39), Medicaid insurance (aPR: 1.19, 95% CI: 1.13-1.24), and residing in the least-educated zip codes (aPR: 1.09, 95% CI: 1.04-1.15) were associated with advanced-stage diagnosis. Among women, advanced-stage diagnosis was associated with NH-Asian race (aPR: 1.23, 95% CI: 1.06-1.42). HIV status was not independently associated. Conclusions: Correlates of advanced-stage SCCA differed by sex; living with HIV was not associated with advanced-stage presentation. Impact: These findings identify NH-Black and NH-Asian women, uninsured individuals, and Medicaid enrollees as populations more likely to be diagnosed with advanced-stage SCCA.