Blacks are more likely than whites to have large colon polyps, and their tumors tend to be located higher in the colon where they are harder to detect, U.S. researchers said on Tuesday.

Blacks are already known to have higher rates of colon cancer than whites and up to 43 percent higher death rates from the disease, which kills 52,000 Americans annually.

Researchers said several factors may account for the racial disparity in colon cancer rates, including genetic differences that account for about a third of all cases of the disease. But blacks also have poorer access to health care and lower rates of participation when screening is offered.

Since 1985, colon cancer has risen among black men and is unchanged among black women, while declining by as much as 25 percent among whites, the report in the Journal of the American Medical Association said.

Early detection of colon cancer is considered a key to successful treatment.

In a study of nearly 5,500 blacks and more than 80,000 whites who had colonoscopies, researchers at Portland VA Medical Center found nearly 8 percent of blacks had one or more polyps sized more than 9 millimeters in diameter compared to slightly more than 6 percent of whites.

The tumors detected in blacks were more likely to be in the upper part of the colon where a sigmoidoscopy - a procedure that looks only at the lower half of the colon - would be unlikely to find it.

The incidence of large polyps was noticeably high among black women younger than age 50, the age when adults are recommended to begin getting regular colonoscopies.

“If this finding is confirmed in other studies, consideration should be given to initiation of screening before age 50 years in black women,” wrote David Lieberman, who led the team performing the study.

“These data strongly emphasize the importance of timely screening in black women and men,” he added.

CHICAGO (Reuters)