June 26, 2008 — Patients with low socioeconomic status have a higher death rate after a cancer diagnosis, report researchers. Could poverty be a risk factor for all-cause mortality? In a study published online June 23 in Cancer, investigators suggest that it is, and they attribute the higher death rate to later disease stage at diagnosis and less aggressive treatment.
The study is part of the national program of cancer registries — a collaborative inquiry that includes data from 7 states: California, Colorado, Illinois, Louisiana, New York, Rhode Island, and South Carolina. It is funded and coordinated by the Centers for Disease Control and Prevention.
"Patients with a lower socioeconomic status have a 35% increase in mortality," lead author Tim Byers, MD, from the Colorado School of Public Health, in Aurora, told Medscape Oncology. "Economics appear to be playing a role in cancer disparities."
Economics Playing a Role in Cancer Disparities
Other studies have shown an increased risk in cancer and mortality rates among minorities and those without health insurance in the United States. During an interview, Sheryl Gabram, MD, from Emory University and Grady Memorial Hospital, in Atlanta, Georgia, said that black women, for example, typically have a 30% increased mortality rate.
Dr. Gabram and her team published a separate study in the same issue of Cancer. The group breaks the many reasons for cancer disparities into 3 main areas:
environment (social and systemic),
genetics (biology and tumor factors), and
lifestyle (behavioral issues).
"Factors that contribute to the later stage at diagnosis and poorer outcome include differences in diagnosis, tumor characteristics, and treatment," Dr. Gabram said. "These differences are related to both patient- and system-level factors, including socioeconomic and demographic factors, cultural beliefs, healthcare access, comorbid conditions, and tumor biology."
But Dr. Byers questions the extent to which genetics and biology are really contributing to the disparities. "This is a loaded and controversial question of both professional and public sensitivity and, obviously, many factors play a role," he said. "But in our study, social factors seemed to be more important than biologic factors in explaining racial and ethnic cancer disparities."
Dr. Byers pointed out that in his work, socioeconomic-related disparities were much less apparent among patients over the age of 65 years. In the United States, Medicare is nearly universal for citizens at this age.
The authors also point to data suggesting that there is a larger racial disparity in cancer mortality in the United States, where access to medical care is tied to economic status, than in Canada, where access is more universal.
In this large population-based study, investigators reviewed medical records to determine disease stage, treatment, and 5-year mortality rates. They identified socioeconomic status by analyzing income and education at the census-tract level for:
4844 women with breast cancer,
4332 men with prostate cancer, and
4422 patients with colorectal cancer.
The researchers found that low socioeconomic status was associated with more advanced disease stage and with less aggressive treatment for all 3 cancers. For breast and prostate cancer, the age-adjusted all-cause mortality risk was much higher in patients with a low income.
Low Socioeconomic Status Linked to 5-Year All-Cause Mortality
|Age-Adjusted Mortality Risk||Hazard Ratio||95% Confidence Interval|
|Breast cancer||1.59||1.35 – 1.87|
|Prostate cancer||1.33||1.13 – 1.57|
"It is increasingly apparent that a substantial proportion of the disparities in cancer defined by race and ethnicity can be attributed to socioeconomic status," write the researchers. "And because socioeconomic status can be estimated now quite easily either by enhancing medical-record and tumor-record systems or by using geocoding methods like those we used in the current study, it would be prudent for cancer-surveillance systems to routinely report cancer incidence and mortality data by socioeconomic levels."
Speaking to Medscape Oncology, Dr. Byers added that "understanding the ways in which socioeconomic status affects mortality is important for defining strategies to eliminate the unequal burden of cancer by race and ethnicity."
During an interview, Dr. Gabram echoed some of these concerns. Her team has developed an outreach and internal navigation program to address the need in the community. This approach is the topic of their new study published in Cancer (read Outreach and Patient-Navigation Programs Improve Cancer Care on Medscape Medical News).
The researchers have disclosed no relevant financial relationships.
Cancer. Published online before print June 23, 2008.
Medscape Medical News © 2008 Medscape
Cite this: Allison Gandey. Poverty Boosts Mortality Risk After Cancer Diagnosis, Study Shows - Medscape - Jun 26, 2008.