Socioeconomic status and survival in older patients with melanoma

Abstract

Objectives: To determine the association between socioeconomic status (SES) and survival in older patients with melanoma.

Design: Retrospective cohort study.

Setting: Surveillance, Epidemiology and End Results (SEER): a population-based cancer registry covering 14% of the U.S. population.

Participants: Twenty-three thousand sixty-eight patients aged 65 and older with melanoma between 1988 and 1999.

Measurements: Outcome was melanoma-specific survival. Main independent variable was SES (measured as census tract median household income) taken from the SEER-Medicare linked data.

Results: Subjects residing in lower-income areas (< or =30,000 dollars/y) had lower 5-year survival rates (88.5% vs 91.1%, P < .001) than subjects residing in higher-income areas (>30,000 dollars/y). In Cox proportional hazard models, higher income was associated with lower risk of death from melanoma (hazard ratio = 0.88, 95% confidence interval = 0.79-0.98, P = .02) after adjusting for sociodemographics, stage at diagnosis, thickness, histology, anatomic site, and comorbidity index. There was an interaction effect between SES and ethnicity and survival from melanoma. For whites and nonwhites (all other ethnic groups), 5-year survival rates increased as income increased, although the effect was greater for nonwhites (77.6% to 90.1%, 1st to 5th quintiles, P = .01) than for whites (89.0% to 91.9%, 1st to 5th quintiles, P < .001).

Conclusion: Older subjects covered by Medicare residing in lower-SES areas had poorer melanoma survival than those residing in higher-SES areas. Further research is needed to determine whether low SES is associated with late-stage disease biology and poorer early detection of melanoma.

Figure 1

Five-year Kaplan-Meier survival rates by income quintiles and ethnic groups. CI = confidence interval.