The finding is partially but not wholly explained by socioeconomic status, meaning that in addition to the health risks associated with low socioeconomic status or stage of presentation, there are additional health risks associated specifically with these racial/ethnic identities.
"As with many disparities, you have to identify the problem before you can fix it," says Meryl Colton, MS, medical student at University of Colorado School of Medicine, who performed the analysis with Adam L. Green, MD, investigator at the CU Cancer Center and pediatric oncologist at Children's Hospital Colorado.
The study used data from the National Cancer Institute Surveillance, Epidemiology and End Results (SEER) database to compare the overall rate of death in the two years following cancer diagnosis for the three above-mentioned racial/ethnic groups, as well as people with Medicaid or no insurance compared to private insurance. For example, taking the chance of a young-adult white patient dying within two years of being diagnosed with liver cancer as a baseline of "1", the chance of a similar Hispanic white patient dying is 1.77 and a non-Hispanic black patient's chance of dying is 1.76.
This increased risk of mortality for black and Hispanic patients, as well as those without private health insurance, holds true across cancer types including germ cell tumors, soft tissue sarcomas, lymphomas and leukemias.
Much of this disparity is explained by the overlap between low socioeconomic status and racial/ethnic minority status, meaning that the increased chance of dying after a cancer diagnosis is due in part to conditions associated with having less financial resources no matter one's race/ethnicity. However, even after controlling for insurance status, an indicator of socioeconomic status, and stage of presentation, disparities in death rates after cancer diagnosis remained between these racial/ethnic groups, implying an influence of race/ethnicity independent of financial resources.
"This is a starting point," says Colton. "Part of an analysis like this is saying, 'hey, this exists!' And now the second part is trying to figure out why this is happening."
Though additional study is certainly required, Colton points to three possible components of this continuing disparity: The possibility that residual socioeconomic factors could influence a patient's diagnosis and/or care, the possibility for genetically distinct forms of these diseases to make cancers more dangerous in certain populations, or the possibility that the medical system fails to offer equal diagnosis and treatment across racial/ethnic groups.
"This is a population that shouldn't be getting cancer and it's devastating when they do," Colton says. "Knowing that a disparity exists allows us to ask questions that can help ensure everyone receives the best possible care."
The American Society of Clinical Oncology (ASCO) annual meeting 2016, Chicago, Illinois