The relationship between cancer incidence, stage and poverty in the United States

We extend a prior analysis on the relation between poverty and cancer incidence in a sample of 2.90 million cancers diagnosed in 16 US states plus Los Angeles over the 2005-2009 period by additionally considering stage at diagnosis. Recognizing that higher relative disparities are often found among less-common cancer sites, our analysis incorporated both relative and absolute measures of disparities. Fourteen of the 21 cancer sites analyzed were found to have significant variation by stage; in each instance, diagnosis at distant stage was more likely among residents of high-poverty areas. If the incidence rates found in the lowest-poverty areas for these 21 cancer sites were applied to the entire country, 18,000 fewer distant-stage diagnoses per year would be expected, a reduction of 8%. Conversely, 49,000 additional local-stage diagnoses per year would be expected, an increase of 4%. These figures, strongly influenced by the most common sites of prostate and female breast, speak to the trade-offs inherent in cancer screening. Integrating the type of analysis presented here into routine cancer surveillance activities would permit a more complete understanding of the dynamic nature of the relationship between socioeconomic status and cancer incidence.