Black people with advanced colon cancer are less likely to get consultations with specialists and treatment with complex medicines than white people, according to a new study.
Those treatment differences may explain why black patients with the disease are 15 percent more likely to die than their white counterparts, researchers suggest.
“This disparity in treatment does result in survival differences that are quite substantial,” Dr. James Murphy told Reuters Health.
Murphy is the study’s senior author and an assistant professor in the Department of Radiation Medicine and Applied Sciences at the University of California, San Diego.
Colon cancer is the second leading cause of cancer death in the U.S., Murphy and his colleagues write in the Journal of the National Cancer Institute.
Previous studies have found black people are more likely to develop colon cancer, have more advanced cancer when diagnosed and are more likely to die of the disease than patients of other races.
By country in the UK
Bowel cancer is the fourth most common cancer in the UK (2010), accounting for 13% of all new cases. It is the third most common cancer in both males (14% of the male total) and females (11%).
In 2010, there were 40,695 new cases of bowel cancer in the UK: 22,834 (56%) in men and 17,861 (44%) in women, giving a male:female ratio of 13:10. The crude incidence rate shows that there are around 75 new bowel cancer cases for every 100,000 males in the UK and around 56 for every 100,000 females.
Almost two-thirds (66%) of all bowel cancers are cancers of the colon and over one-third (34%) are cancers of the rectum (including the anus). More rectal cancer cases occur in men (8,753 or 63% male), while colon cancer cases are similar between men and women (14,081 or 53% male). The crude incidence rate shows that there are around 75 new bowel cancer cases for every 100,000 males in the UK and around 56 for every 100,000 females.
The European age-standardised incidence rates (AS rates) are significantly lower in England compared with Wales (males only), Scotland and Northern Ireland. The rates do not differ significantly between Wales, Scotland and Northern Ireland for males, but rates are significantly lower in Wales compared to Scotland and Northern Ireland for females.
For the new study, the researchers used data on 9,935 white and 1,281 black patients with late-stage colon cancer from a national database.
All of the patients were at least 66 years old and were diagnosed between 2000 and 2007. The study followed them until they died or through 2009.
Almost three-quarters of the patients had surgery to remove tumors from their colon or rectum and 5 percent also had surgery to remove tumors that had spread to their liver or lungs.
Half of the patients received chemotherapy and 13 percent received radiation.
Compared to whites, black patients were 10 percent less likely to undergo surgery to remove their original tumors and 40 percent less likely to have liver or lung procedures. They were also 17 percent less likely to get chemotherapy and 30 percent less likely to get radiation.
White patients lived - on average - a little more than six months after being diagnosed. That compared to less than five months among black patients.
Overall, 95 percent of the patients died during the study period. But the researchers found black patients were still 15 percent more likely to die than white patients.
INCIDENCE OF COLORECTAL CANCER
Colorectal cancer is a major cause of morbidity and mortality throughout the world. It accounts for over 9% of all cancer incidence. It is the third most common cancer worldwide and the fourth most common cause of death. It affects men and women almost equally, with just over 1 million new cases recorded in 2002, the most recent year for which international estimates are available. Countries with the highest incidence rates include Australia, New Zealand, Canada, the United States, and parts of Europe. The countries with the lowest risk include China, India, and parts of Africa and South America.
In the United States, colorectal cancer is the third most common cancer diagnosis among men and women. There are similar incidence rates for cancer of the colon in both sexes, and a slight male predominance for rectal cancer. In 2005, the most recent year for which U.S. statistics are currently available, ~108,100 and 40,800 individuals were diagnosed with cancer of the colon and rectum, respectively. For 2008, it was estimated that ~148,900 new cases would be diagnosed and ~49,900 people would die of the disease.
To help determine why that was the case, the researchers tried to account for differences between the patients and their tumors. That only explained some of that 15 percent.
After adjusting the numbers for the differences in treatment, however, the increased risk of death among black patients disappeared, according to the researchers.
“The findings are consistent with a lot of other findings in the cancer care literature,” Sam Harper told Reuters Health. “We do see notable racial differences in survival and some of these do seem to be explained by differences in demographic factors and treatment differences.”
Worldwide, colorectal cancer represents 9.4% of all incident cancer in men and 10.1% in women. Colorectal cancer, however, is not uniformly common throughout the world. There is a large geographic difference in the global distribution of colorectal cancer. Colorectal cancer is mainly a disease of developed countries with a Western culture. In fact, the developed world accounts for over 63% of all cases. The incidence rate varies up to 10-fold between countries with the highest rates and those with the lowest rates. It ranges from more than 40 per 100,000 people in the United States, Australia, New Zealand, and Western Europe to less than 5 per 100,000 in Africa and some parts of Asia. However, these incidence rates may be susceptible to ascertainment bias; there may be a high degree of underreporting in developing countries.
Harper was not involved with the study but has researched racial disparities in cancer care as an assistant professor at McGill University in Montreal.
Murphy added, however, that his team’s study cannot explain why the differences in treatment exist.
Differences in healthcare access, doctor biases and patient mistrust could play a role.
“I think the take-home point is that we need more research into treatment barriers to see how they can be overcome,” Murphy said.
Harper agreed that more research is needed into why black patients and white patients have different treatment experiences.
“I think this continues to be an important question to focus on,” he said.
Murphy said it’s hard to know what patients can do to make sure they don’t fall into the disparity gap.
“I think for providers just understanding that there is a disparity out there may make them aware and help reduce the disparity,” he said. “But we do need more research to identify individual barriers.”
SOURCE: Journal of the National Cancer Institute, online November 14, 2013.
Racial Disparity in Consultation, Treatment, and the Impact on Survival in Metastatic Colorectal Cancer
Background Black patients with metastatic colorectal cancer have inferior survival compared to white patients. The purpose of this study was to examine disparity in specialist consultation and multimodality treatment and the impact that treatment inequality has on survival.
Methods We identified 9935 non-Hispanic white and 1281 black patients with stage IV colorectal cancer aged 66 years and older from the Surveillance, Epidemiology, and End Results (SEER)–Medicare linked database. Logistic regression models identified race-based differences in consultation rates and subsequent treatment with surgery, chemotherapy, or radiation. Multivariable Cox regression models identified potential factors that explain race-based survival differences. All statistical tests were two-sided.
Daniel R. Simpson,
María Elena Martínez,
Loren K. Mell,
Quynh-Thu Le and
James D. Murphy