BACKGROUND

Racial and ethnic disparities in mortality persist among US cancer survivors, with social determinants of health (SDoH) may have a significant impact on these disparities.

METHODS

A population-based cohort study of a nationally representative sample of adult cancer survivors, who participated in the US National Health and Nutrition Examination Survey from 1999 to 2018 was included. Sociodemographic characteristics and SDoH were self-reported using standardized questionnaires in each survey cycle. The SDoH was examined by race and estimated for associations with primary outcomes, which included all-cause and cancer-specific mortality. Multiple mediation analysis was performed to assess the contribution of each unfavorable SDoH to racial disparities to all-cause and cancer-specific mortality.

RESULTS

Among 5163 cancer survivors (2724 [57.7%] females and 3580 [69.3%] non-Hispanic White individuals), only 881 (24.9%) did not report an unfavorable SDoH. During the follow-up period of up to 249 months (median 81 months), 1964 deaths were recorded (cancer, 624; cardiovascular, 529; other causes, 811). Disparities in all-cause and cancer-specific mortality were observed between non-Hispanic Black and White cancer survivors. Unemployment, lower economic status, education less than high school, government or no private insurance, renting a home or other arrangements, and social isolation were significantly and independently associated with worse overall survival. Unemployment, lower economic status, and social isolation were significantly associated with cancer-specific mortality. Compared to patients without an unfavorable SDoH, the risk of all-cause mortality was gradually increased in those with a cumulative number of unfavorable SDoHs (1 unfavorable SDoH: hazard ratio [HR] = 1.54, 95% CI 1.25-1.89; 2 unfavorable SDoHs: HR = 1.81, 95% CI 1.46-2.24; 3 unfavorable SDoHs: HR = 2.42, 95% CI 1.97-2.97; 4 unfavorable SDoHs: HR = 3.22, 95% CI 2.48-4.19; 5 unfavorable SDoHs: HR = 3.99, 95% CI 2.99-5.33; 6 unfavorable SDoHs: HR = 6.34 95% CI 4.51-8.90). A similar trend existed for cancer-specific mortality.

CONCLUSIONS

In this cohort study of a nationally representative sample of US cancer survivors, a greater number of unfavorable SDoH was associated with increased risks of mortality from all causes and cancer. Unfavorable SDoH levels were critical risk factors for all-cause and cancer-specific mortality, as well as the underlying cause of racial all-cause mortality disparities among US cancer survivors.