Cancer patients with low socioeconomic status (SES) have more advanced cancers at diagnosis, receive less aggressive treatment, and have a higher risk of dying in the five years following cancer diagnosis, according to a new study. The study, to be published in the journal Cancer, supports the need to focus on SES as an underlying factor in cancer disparities by race and ethnicity.
Racial and ethnic disparities in the diagnosis and treatment of cancer and in risk of death after cancer have been documented by many studies. But the role that socioeconomic status might play, in addition to race and ethnicity, has been less well-studied.
To explore the association between SES and mortality, Tim Byers, M.D. of the University of Colorado Denver and colleagues from seven states conducted the Breast, Colon, and Prostate Cancer Data Quality and Patterns of Care (POC) Study, a collaborative inquiry by seven state cancer registries within the National Program of Cancer Registries. The researchers documented compete information on cancer stage, treatment received, and 5-year mortality rates from multiple medical record sources for 13,598 cancer cases diagnosed in seven states in 1997, including 4,844 women with breast cancer, 4,332 men with prostate cancer, and 4,422 men and women with colorectal cancer. They also determined the socioeconomic status of the neighborhood of each patient by using the neighborhood-specific income and education data from the 2000 U.S. census.
Their analysis revealed that for all three types of cancers, individuals of low socioeconomic status had more advanced stages of cancer and received less aggressive treatment. For example, women of low socioeconomic status were less likely to receive radiation treatment after a lumpectomy or to receive anti-estrogen therapy when diagnosed with an estrogen receptor positive (ER+) tumor. Men with prostate cancer who were living in areas of low socioeconomic status were less likely to have been treated by prostatectomy or radiation compared to men from areas of high socioeconomic status. Chemotherapy was also less likely to be used for low socioeconomic status men and women with colorectal cancer.
For all three types of cancer, patients who lived in low SES neighborhoods were more likely to die in the five years following their cancer diagnosis than were patients in higher SES neighborhoods. A substantial proportion of this difference seemed to be due to the combined effects of this less intensive treatment and to a later stage of cancer at the time of diagnosis. While African-Americans and Hispanics were more likely than non-Hispanic whites to have lived in areas of low socioeconomic status, the investigators say that the low SES factor was apparent for all racial and ethnic groups. Disparities related to socioeconomic status were not as apparent among patients aged 65 and older, perhaps because nearly everyone over age 65 is provided access to cancer screening and treatment via Medicare, regardless of their socioeconomic status.
"These findings support the need to focus on socioeconomic status as an important underlying factor in cancer disparities by race and ethnicity," the authors concluded. "We need better information on how access to health care contributes to differences in cancer outcomes by socioeconomic status in order to address the root causes of racial and ethnic cancer disparities in the United States," they added.
Cancer, August 1, 2008, published online June 23, 2008
American Cancer Society (http://www.cancer.org)