Racial/Ethnic Disparities in Cancer-Specific Survival in California

Key Points

  • The stage at diagnosis was the greatest contributor to cancer-specific survival disparities.
  • Neighborhood socioeconomic status and marital status were important contributors.

In a study using California Cancer Registry data reported in the Journal of Clinical Oncology, Ellis et al found that the stage at diagnosis was the greatest contributor to racial/ethnic disparities in cancer-specific survival, with neighborhood socioeconomic status and marital status also being important contributors.

Study Details

The study included data on 877,662 cancer cases and 222,042 cancer-specific deaths among black, Hispanic, Asian American/Pacific Islander, and white patients diagnosed with breast, prostate, colorectal, or lung cancer between 2000 and 2013 in California. The percentage contribution of tumor, treatment, hospital, sociodemographic, and neighborhood factors to overall racial/ethnic survival disparities was estimated from a sequence of multivariable Cox proportional hazards models.

Factors in Disparity

In baseline models, black patients had the lowest survival for all types of cancer, and Asian American/Pacific Islander patients had the highest survival. The stage at diagnosis appeared to be the greatest contributor to survival disparities, accounting for 24% of disparities in breast cancer, 24% in prostate cancer, and 16% to 30% in colorectal cancer.

With regard to other contributors:

  • In breast cancer, neighborhood socioeconomic status accounted for approximately 7% of disparities in black and Hispanic women, hormone receptor status accounted for 9% of overall disparity, and adjustment for all covariables accounted for 54% of overall disparities.
  • In prostate cancer, 14% of the disparity was explained by differences in marital status and 7% by neighborhood socioeconomic status, and adjustment for all covariables accounted for 48% of overall disparities.
  • In lung cancer, adjustment for the stage at diagnosis increased disparities across all groups by 17% in men and 30% in women. Differences in neighborhood socioeconomic status accounted for 18% and 17% of disparities in men and women; differences in marital status accounted for 21% and 14%, tumor histology accounted for 19% overall, and adjustment for all covariables accounted for 15% to 40% of disparities.
  • In colorectal cancer, marital status accounted for 16% of disparities in men and 13% in women, neighborhood socioeconomic status accounted for approximately 6%, and adjustment for all covariables explained 52% to 55% of overall disparities.

Overall, neighborhood socioeconomic status was an important factor in all cancers, but only for black and Hispanic patients, and the influence of marital status was greater in men than in women.

The investigators concluded: “Stage at diagnosis had the largest effect on racial/ethnic survival disparities, but earlier detection would not entirely eliminate them. The influences of neighborhood socioeconomic status and marital status suggest that social determinants, support mechanisms, and access to health care are important contributing factors.”

The study was supported by the Stanford Cancer Institute and the National Cancer Institute.

Libby Ellis, PhD, of the Cancer Prevention Institute of California, is the corresponding author of the Journal of Clinical Oncology article.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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