The study, published in the Aug. 7 issue of the Journal of the National Cancer Institute, provides new evidence that a lack of access to quality care, rather than an innate biological difference, is largely to blame for the generally lower survival rates of African-Americans with colon cancer, the authors say.
"Most researchers have suspected that the lower survival rate among African-Americans with colon cancer is due to variations in the availability of adequate medical care rather than any unique characteristics of their tumors," says the study's senior author, Charles Fuchs, M.D., of Dana-Farber. "This study indicates that when African-American and white patients receive the same basic treatment for the disease – surgery followed by chemotherapy – they fare equally well."
Data for the study came from a clinical trial designed to measure the effectiveness of chemotherapy for colon cancer patients who had undergone surgery to remove cancerous portions of their colons.
Fuchs and his colleagues compared survival rates and the level of side effects in 344 African-American and 3,036 white patients enrolled in the trial. The patients all had cancer of the colon that was removed surgically within the prior six weeks. As part of the trial, all patients received six to eight weeks of chemotherapy after surgery.
The investigators found no major differences in survival rates for the two groups five years after treatment. The African-American patients had a 65 percent overall survival rate compared to 66 percent for the white patients. Similarly, they had a 57 percent recurrence-free survival rate and the white patients had a 58 percent rate.
The data also showed that white patients were significantly more likely than African-American patients to experience chemotherapy-related side effects, including diarrhea (sometimes severe), nausea, vomiting, and stomatitis (an inflammation of the mouth). The reasons for these differences in chemotherapy-related side effects aren't clear, Fuchs and his co-authors write, but may have to do with undefined genetic differences between whites and African-Americans in the general population.
Although previous studies have found that African-Americans with colon cancer generally don't survive as long as whites with the disease, the new study is one of the first to compare survival rates when the availability of quality care is equal for all patients. If African-Americans as a group have poorer access to such care, their tumors are less likely to be detected and treated at an early stage, when prospects for recovery are best.
"Our study shows the value of the National Cancer Institute's efforts to increase African-Americans' participation in clinical trials," explains the study's first author, A. David McCollum, M.D., who conducted the research while he was at Dana-Farber and is now a practicing oncologist in Texas. "Increased enrollment by members of minority groups will ultimately lead to better care for people in traditionally underserved populations."
Contributing to the study were investigators at the University of Pennsylvania Cancer Center, St. Vincent Clinical Cancer Center in New York City, and Northwestern University.
The study was funded in part by grants from the National Cancer Institute and Dana-Farber.
Dana-Farber Cancer Institute (www.dana-farber.org) is a principal teaching affiliate of the Harvard Medical School and is among the leading cancer research and care centers in the United States. It is a founding member of the Dana-Farber/Harvard Cancer Center (DF/HCC), designated a comprehensive cancer center by the National Cancer Institute.
Journal
JNCI Journal of the National Cancer Institute