Later diagnosis and differences in treatment may be among the reasons that African Americans are less likely than whites to survive colon cancer, a study published Monday suggests.

It has long been recognized that black Americans have a poorer colon cancer survival rate than their white counterparts, and recent studies suggest that the racial gap is growing rather than shrinking.

In the new study, published online by the journal Cancer, researchers found a number of factors that may help explain the difference.

Using government data on nearly 9,100 Americans diagnosed with colon cancer between 1988 and 1992, the researchers found that African Americans were 13 percent more likely to die within five years than white patients were.

In general, African Americans were more likely to have advanced cancer at diagnosis; nearly 48 percent were diagnosed with stage III or IV cancer -- where the tumor has spread beyond the colon -- compared with 43 percent of white patients.

There were also racial differences in the likelihood of having surgery, a treatment that was directly related to survival. Almost 17 percent of African Americans did not receive surgery, versus roughly 11 percent of whites.

When several factors were weighed -- including socioeconomics, the stage of the cancer at diagnosis and type of treatment -- race itself was no longer a predictor of survival.

That meant that the reasons for the disparities in treatment and cancer stage at diagnosis are not clear, said senior researcher Dr. Michael S. Simon, of the Karmanos Cancer Institute at Wayne State University in Detroit.

It's possible that African Americans were not getting screened for colon cancer as often or as early as whites, Simon told Reuters Health, but the National Cancer Institute database used for the study does not contain information on screening.

The debate about the disparity (in colon cancer survival) has basically been whether it's related to genetics or socioeconomics, Simon said, adding that he thinks it is the latter.

Differences in access to good healthcare, diet and lifestyle may all play a role in African Americans' poorer colon cancer, according to Simon. He stressed that this study had no data on factors like diet and healthcare, but they are typically closely related to socioeconomics -- which the study did link to colon cancer survival.

Another recent study, however, that appeared in the Journal of the National Cancer Institute, found that African Americans who developed breast, ovary, and prostate cancer had worse outcomes even when they received the same care. That suggested that there is something that 'tracks' with African ancestry for these three diseases, a co-author of that study, Dr. Kathy S. Albain of Loyola University Medical Center in Maywood, Illinois, told Reuters Health earlier this month.

Still, there are measures that individuals, regardless of race, can take to lower their risk of colon cancer, Simon noted.

Studies suggest that regular exercise and a diet rich in fruits, vegetables and fiber, but low in red meat, may be protective. People may also improve their odds by not smoking and limiting their alcohol intake.

Experts advise all adults at average risk of colon cancer to start getting screened at the age of 50. Some screening options include yearly tests looking for blood in the stool and a colonoscopy every 10 years.

Some experts have suggested that African Americans should start screening at age 45. As it stands, however, only certain groups at elevated risk of colon cancer -- such as people with a strong family history of the disease -- are advised to start screening before age 50.

SOURCE: Cancer, online July 13, 2009.