FRIDAY, Dec. 30 (HealthDay News) -- Although colorectal cancer death rates in the United States have fallen across the board over the last 20 years, the dip has been smaller among blacks than whites, a new study indicates.

Specifically, the racial spread in death rate trends appears to be most notable among patients diagnosed with the most advanced stage of the disease, according to the results of an investigation by the American Cancer Society (ACS).

"The widening racial disparity for [advanced]-stage has a disproportionate impact on overall colorectal cancer mortality disparities because [advanced]-stage accounts for approximately 60 percent of the overall black-white mortality disparity," the study authors explained in an ACS news release.

The study team, led by Dr. Anthony Robbins, pointed out that up until 1980, black Americans were actually less likely to die from colorectal cancer overall than whites. Since then, however, the availability of ever-better screening and treatment options has turned that dynamic on its head. The result: by 2007, the rate of death among blacks was 44 percent greater than that among whites.

The reason, the authors suggested, may be that black patients do not seem to be getting screened or treated as often and as aggressively as white patients.

The aim of the current ACS study was to find out how exactly racial differences in plummeting death rates have been playing out with respect to disease progression: namely, early-stage (in which cancer is localized); mid-stage (in which cancer has spread to regional lymph nodes); and late-stage (in which the cancer is made its way throughout the patient's body).

To explore that question, the team analyzed two decades of information that had already been gathered by the U.S. National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program database.

The review, released online Dec. 19 in advance of print publication in the Journal of Clinical Oncology, revealed that while racial differences in death rate declines were apparent at every stage of disease, the divide was most stark among late-stage patients.

For example, while early-stage white patients experienced a roughly 30 percent drop in death rates over the last 20 years, their black peers experienced about a 13 percent decline. Among mid-stage patients, the drop was almost 49 percent among whites versus 34 percent among blacks.

But for those with the most advanced stage of disease, the gap was even greater: death rates had dropped by nearly 33 percent among whites compared with just under 5 percent among blacks, the investigators found.

The authors noted that black Americans tend to be screened less often, are less likely to have timely follow-ups when they are screened, and are generally less well informed when it comes to the latest and best treatment options. The researchers suggested that to rectify the problem, an effort should be made to bump up early-stage detection of colorectal cancer among black patients.

More information

For more on colorectal cancer, visit the U.S. National Cancer Institute.