PURPOSE Despite narrowing racial gaps, disparities persist across cancer types and socioeconomic levels. The diminishing returns hypothesis suggests that economic advantage yields fewer health benefits for Black individuals but is largely unexplored in the context of cancer. We examined the diminishing returns among Black and White individuals across cancer types using a nationally representative study population. METHODS The study analyzed cancer-specific survival among 5.3 million non-Hispanic Black and White adults diagnosed with primary cancer (2006-2020) using SEER-22. We assessed how race and neighborhood socioeconomic status (SES) jointly affects survival across 21 cancer types. A 10-level race-SES variable was created, using White individuals in the highest-SES group as the reference. The main outcome was cancer-specific death. Diminishing returns were defined quantitively and qualitatively as worse survival for Black individuals even at higher SES. Cox models adjusted for demographics and clinical factors, with multiple imputation for missing data. Social gradients were also evaluated. RESULTS Black women showed strong evidence of diminishing returns overall and for seven cancers, especially uterine and breast cancers. A social gradient was also evident in cancers with diminishing returns, except uterine cancer. For Black men, diminishing returns were not observed across all cancers combined but was present in eight cancers—including prostate and colorectal cancers. Most cancers among men exhibited a strong social gradient. Findings were consistent by time period and upon restricting to localized and regional disease in sensitivity analyses. CONCLUSION Higher SES improves cancer survival for White patients but not Black patients, worsening racial disparities for certain cancers.
McCullough et al. (2026) studied this question.