Comparing anal cancer characteristics between Asian American and Pacific Islander subgroups.

Abstract

e15506 Background: Analyses of anal cancer (AC) typically combine Asian Americans and Pacific Islanders (AAPI) into a single “AAPI” group. However, whether this aggregation masks disparities in AC outcomes between AAPI subgroups is unknown. In this study, we compared AC characteristics and outcomes between AAPI subgroups disaggregated by region. Methods: We identified 51,835 patients with AC in the National Cancer Database (2009–2020) after excluding patients missing data for race or stage. The combined AAPI group (n=451) included East Asian (n=173), Southeast Asian (n=142), South Asian (n=74), and Pacific Islander (PI) (n=62) subgroups. Logistic regression analyzed odds of advanced stage (III–IV) and high-grade cancer at diagnosis. Cox regression analyzed three-year overall survival (OS). These analyses used Non-Hispanic White (NHW) (n=45,135) as the reference group and adjusted for confounding by age, comorbidity score, payer type, zip code income quartile, and diagnosis year. This protocol was developed and reviewed by oncology faculty prior to implementation. Results: When combined, the AAPI group showed an adjusted odds ratio (aOR) of 1.40 (95% CI 1.15–1.71; p<0.001) for advanced stage disease, aOR of 1.21 (0.78–1.85; p=0.40) for high-grade disease, and a hazard ratio (HR) of 1.12 (0.92–1.38; p=0.27) for three-year OS compared to NHW patients. When separated, only East Asians showed significantly increased odds of advanced stage disease (aOR 1.49; 95% CI 1.09–2.06; p=0.013) compared to NHW. For high-grade, although no subgroups reached significance, aORs varied from 2.23 (95% CI 0.74–6.95; p=0.15) among PIs to 0.45 (95% CI 0.10–1.43; p=0.22) among South Asians. Southeast Asians showed significantly worse three-year OS (HR 1.52; 95% CI 1.10–2.11; p=0.011). Although no other subgroups reached significance, HRs varied from 1.48 (95% CI 0.86–2.55; p=0.16) for PIs to 0.71 (95% CI 0.38–1.33; p=0.29) among South Asians. Conclusions: Separating the AAPI aggregate group into regional subgroups reveals heterogeneity in anal cancer presentation and outcomes. Non-pooled analyses are limited by both sample size, as evidenced in this study, and availability of data in which AAPI subgroups can be separated. However, disaggregating the AAPI group, even if only into regional subgroups, may reveal important disparities in AC characteristics in future research studies. Anal cancer characteristics for AAPI versus AAPI subgroups. Advanced Stage(aOR, 95% CI) High-Grade (aOR, 95% CI) 3-Year OS (HR, 95% CI) NHW 1.00 (Ref) 1.00 (Ref) 1.00 (Ref) AAPI (Combined) 1.40 (1.15–1.71)** 1.21 (0.78–1.85) 1.12 (0.92–1.38) East Asian 1.49 (1.09–2.06)* 1.55 (0.74–3.20) 0.93 (0.66–1.30) Southeast Asian 1.29 (0.90–1.84) 1.07 (0.49–2.25) 1.52 (1.10–2.11)* South Asian 1.31 (0.80–2.13) 0.45 (0.10–1.43) 0.71 (0.38–1.33) Pacific Islander 1.53 (0.88–2.66) 2.23 (0.74–6.95) 1.48 (0.86–2.55) *p-value <0.05. **p-value <0.001.