Area Socioeconomic Variations in U.S. Cancer Incidence, Mortality, Stage, Treatment, and Survival, 1975–1999

Abstract

Objectives

This report analyzes area socioeconomic differentials and trends in incidence, mortality, stage of disease, treatment, and survival for all cancers combined and for six major cancers (lung, colon/rectum, prostate, breast, uterine cervix, and melanoma of the skin) by sex and race/ethnicity in the United States.

Methods

County and census tract poverty rates from the 1990 census were linked to U.S. mortality, SEER cancer incidence, stage, treatment, and survival data from 1975 to 1999. Age-adjusted incidence and mortality rates were calculated for each area poverty group, and differences in rates were tested for statistical significance at the 0.05 level.

Results

Substantial area socioeconomic gradients in both incidence and mortality were observed for various cancers. The association between area socioeconomic position and cancer mortality changed markedly over the past 25 years. Socioeconomic inequalities in male lung and prostate cancer mortality widened, while those in colorectal and breast cancer mortality narrowed over time and even appear to have reversed in the late 1990s. There was a marked increase in incidence for breast cancer and melanoma of the skin in all socioeconomic groups, with a positive gradient remaining throughout the study period. Socioeconomic inequalities in cervical cancer also persisted against a backdrop of declining incidence and mortality rates. For each of the cancers considered, regardless of race/ethnicity, both men and women in high poverty areas (poverty rates 20% or higher) had substantially higher rates of late-stage cancer diagnosis and lower rates of cancer survival than those in low poverty areas (poverty rates less than 10%). Cancer survival rates for residents of higher poverty areas remained lower even after controlling for differences in stage. Residents of higher poverty areas were also less likely to receive preferred treatment for lung and breast cancers and to undergo radical prostatectomy.

Conclusions

Area socioeconomic differentials in cancer incidence and mortality vary substantially by sex, race/ethnicity, and time period. Area socioeconomic disparities may be associated with similar disparities in the distribution of smoking, diet, physical activity, cancer screening, and treatment. Area socioeconomic measures, when linked to cancer registration and vital statistics data, enhance cancer surveillance research and monitoring.