This may be a major reason blacks with advanced colorectal cancer -- cancer of the colon and rectum -- have a 15 percent higher death rate than whites, according to researchers from the University of California, San Diego.
The risk of death, however, was the same for patients who received the same cancer treatments, such as chemotherapy and surgery, regardless of their race, the researchers said.
The researchers analyzed data from more than 11,000 patients over age 66 who had metastatic colorectal cancer, which is cancer that has spread to other areas of the body. Blacks were 10 percent less likely than whites to have primary tumor surgery, 17 percent less likely to receive chemotherapy and 30 percent less likely to receive radiation therapy.
Chemotherapy was associated with a 66 percent lower risk of death, according to the study, which was published online Nov. 14 in the Journal of the National Cancer Institute.
Among patients who received chemotherapy, whites were more likely than blacks to receive more than one chemotherapy agent. Blacks typically began chemotherapy four days later after diagnosis than whites.
The researchers also found that almost half of the survival disparity between black and white patients was because of treatment differences. After accounting for these differences, the racial disparity in survival disappeared.
Possible reasons for the racial disparities noted in this study include conscious or unconscious biases from health care providers, patient mistrust and health literacy, the researchers said. Breakdowns in communication between patients and their doctors, barriers to health care access and differences in how the disease affects people of different races could also explain the disparities, they said.
"Further studies may answer the important question of why there are racial disparities in consults with cancer specialists and treatment among this population," Dr. James Murphy, chief of the radiation oncology gastrointestinal tumor service at the University of California, San Diego, Moores Cancer Center, said in a university news release. "The answers may lead to areas we can improve upon to close these gaps."
"I suspect that this pattern of disparity could be present in other underserved minority groups as well," he said.
The American Cancer Society has more about colorectal cancer.