Both age and race impact colorectal cancer survival, a new study finds.

African-Americans diagnosed with colorectal cancer at a young age had significantly worse outcomes compared with young white or Hispanic patients.

The number of colorectal cancer diagnoses in patients younger than 50 is increasing, challenging the notion that colorectal cancer is a disease of aging. A recent study found that nearly 15 percent of colorectal cancers were diagnosed before 50.

Little is known about what's happening at the molecular level with these tumors in younger patients. Researchers think these young-onset cancers may be biologically different from the type of tumor that occurs in older people.

Meanwhile, racial disparities in colorectal cancer survival have worsened overall since 2000.

"There are differences between the races, and there may be differences in younger patients," says study author Elena Stoffel, M.D., director of the Cancer Genetics Clinic at the University of Michigan Rogel Cancer Center. "We need to look at tumors that develop in young people and in African-Americans to see if they have molecular differences compared to the typical colorectal cancer seen in older adults."

Disparities due to more than preventive care

The study, published in the Journal of Clinical Oncology, reviewed 28,145 patients diagnosed with colorectal cancer before age 50. Patient information was gathered from the National Cancer Institute's Surveillance, Epidemiology and End Results database of cancer incidence.

Five-year survival was significantly worse at every stage of the disease for African-American patients than for white or Hispanic patients.

In particular, the researchers found that young African-Americans with stage 2 colon cancer have a 60 to 70 percent higher risk of death compared with young white patients. Previous studies have shown disparities are more pronounced in advanced disease.

Many in the research community have attributed racial disparities in colorectal cancer to access to screening. Colorectal cancer screening guidelines recommend starting the tests at age 50. By looking at patients too young to undergo such tests, this new study takes access to screening off the table as a factor in disparities.

Stoffel says she was surprised to see a significant difference in survival among stage 2 cancer cases, which are usually associated with very good prognosis when treated with surgery alone without chemotherapy. Previous studies suggest that patients with stage 2 colon cancer receive minimal, if any, benefit from chemotherapy. But these studies included mostly patients diagnosed at older ages. Oncologists tend to be more likely to offer chemotherapy to young patients, which suggests the possibility that differences in cancer treatment are causing a disparity.

"This is a group for which treatment should make the least difference, and yet we see the biggest disparities in survival," Stoffel says.

"The fact we're seeing a big disparity in outcomes in young people with stage 2 disease suggests that early stage tumors may behave differently in different patients. We need to look more carefully at how we're treating colorectal cancers in young people. If these cancers are molecularly different from your average older-onset cancers, then perhaps they respond differently to treatment."