Study finds survival disparities among patients with colorectal cancer

Disparities in cancer stage and treatment are the main reasons why Medicaid-insured and uninsured rectal cancer patients are twice as likely to die within five years as privately insured patients. That is the conclusion of a new study published early online in Cancer, a peer-reviewed journal of the American Cancer Society. Because poorer survival among rectal cancer patients without private insurance is largely attributable to later cancer stage at diagnosis and inadequate treatment, disparities may be lessened through health care reform.

A number of factors may account for survival disparities seen among patients with colorectal cancer. The likelihood that these patients might die prematurely may be influenced by cancer stage and treatment, health insurance status, and demographic factors such as age, sex, race/ethnicity, and poverty status. To explore the relative contribution of such factors on survival disparities, Anthony S. Robbins, MD, PhD, of the American Cancer Society in Atlanta and his colleagues conducted a study of insurance status and survival among 19,154 rectal cancer patients aged 18 to 64 years, using data from the National Cancer Data Base, a national hospital-based cancer registry. Patients were diagnosed in 1998 to 2002 and were followed through 2007. (The investigators restricted the study to rectal cancer rather than all colorectal cancer because it is staged and treated differently than colon cancer, and previous research on rectal cancer is more limited than research on colon cancer.)

Dr. Robbins and his team examined the impact of 10 factors on 5-year survival: age, sex, race/ethnicity, cancer grade, cancer subtype, neighborhood education and income levels, treatment facility type, cancer stage, and treatment. After adjusting only for age, the researchers found that Medicaid-insured and uninsured patients had twice the risk of privately insured patients of dying within five years. After adjusting for all of the factors listed above, the investigators determined that rectal cancer patients insured through Medicaid had a 34 percent increased risk of dying within five years compared with privately insured patients. Uninsured patients had a 29 percent increased risk of dying within five years compared with privately insured patients. Disparities in cancer stage and treatment accounted for approximately 53 percent of the excess deaths, while factors other than stage and treatment accounted for approximately 17 percent.

"Our main finding, that most of the excess mortality seen among uninsured and Medicaid-insured patients was explained by two modifiable factors (stage and treatment) suggests that improving insurance coverage and reducing cost-related barriers to primary care, colorectal cancer screening, and high-quality treatment would have a major impact on colorectal cancer survival disparities," said Dr. Robbins.