Disparities in stage III–IV squamous cell anal carcinoma (SCAC): Real-world treatment patterns, outcomes, and implications for immunotherapy.

Abstract

6 Background: SCAC is a rare malignancy with rising incidence and few therapeutic advances. Prior studies have shown that Black and male patients (pts) experience worse survival, underscoring persistent inequities in SCAC care. With the recent FDA approval of retifanlimab plus carboplatin–paclitaxel, the first FDA approved regimen in SCAC, understanding real-world inequities is critical to ensure equitable access to novel therapies. Methods: This retrospective study evaluated pts with SCAC who initiated first-line (1L) systemic therapy between January 2019 and December 2023. Eligible pts had stage III or IV disease at diagnosis or had stage I/II disease at diagnosis and later developed metastatic disease. Treatment patterns and outcomes (overall survival [OS], time to treatment discontinuation [TTD], and time to next treatment [TTNT]) were assessed across subgroups defined by race, insurance status, and area deprivation index (ADI). The Kaplan–Meier method was used to estimate OS, TTD, and TTNT. Results: Among 923 pts with SCAC, 69% were White, 7% were Black, and 10% were from the most deprived (Q5) ADI. The most common 1L regimens were fluorouracil + mitomycin (47%) and capecitabine + mitomycin (19%). Striking disparities were observed across the treatment continuum. Black and Medicaid/Medicare pts were more likely to receive single-agent chemotherapy than multi-agent regimens, reflecting differences in treatment intensity that may contribute to poorer outcomes. Single-agent immunotherapy was underutilised overall (4%). Black pts progressed to second-line therapy earlier than White pts (median TTNT 14.1 vs 39.1 months). Medicaid pts (median TTNT 14.1 months) and those from high-ADI regions (21.3 months) also had shorter TTNT compared with commercially insured (not reached) and the least deprived pts (38.4 months). TTD was uniformly short (~1.9 months) across groups, underscoring high rates of early discontinuation. The 24-month OS rate was 63% for Black pts compared with 77% for White pts, and 60% for Medicaid pts compared with 80% for commercially insured pts. Pts from the most deprived regions (Q5 ADI) had a lower 24-month OS rate (59.1%) compared with the least deprived (Q1) regions (70.5%). Conclusions: Disparities in treatment persistence and survival were evident among pts with SCAC, disproportionately affecting Black pts, Medicaid beneficiaries, and those from socioeconomically deprived areas. These inequities highlight systemic barriers that limit equitable cancer care. While the approval of retifanlimab provides a new therapeutic option for pts with advanced/metastatic disease, the broader inequities observed underscore the need for deliberate strategies to ensure equitable access as novel therapies are introduced.