Study suggests disparity in colorectal cancer demographics and outcomes between various races

American College of GastroenterologyOct 19 2010

Could impact medical guidelines for screening and treatment of colorectal cancer

The latest colorectal cancer research presented at the American College of Gastroenterology's (ACG) 75th Annual Scientific meeting in San Antonio this week strengthens the growing body of evidence that suggests significant disparity in colorectal cancer (CRC) demographics and outcomes between various races.

In the first in a series of studies investigating colorectal cancer disparities that exist between various races, researchers conducted a retrospective analysis of colonoscopies performed in young patients from July 2003 to December 2009, excluding those with a family history of colorectal cancer or a known history of inflammatory bowel disease. The study, "Yield of Colonoscopy in the Young: Should Screening for Hispanic Population Begin at an Earlier Age as in African Americans?," reviewed the reasons these young patients (18‐45) underwent colonoscopy and the results of their procedures and compared the findings between different ethnic groups.

"Significant pathology was found in 7.4 percent of young patients (cancer 3.3 percent and adenomatous polyps 4.1 percent)," said researcher Arya Karki, M.D. "In African American and Hispanic patients, cancer was found in 5.1 percent and 3.3 percent respectively. Though retrospective and with a relatively small sample size, our data suggest comparable rates of cancer between young African American and Hispanic patients," said Dr. Karki. He added that a large prospective study is needed to confirm these results before recommending earlier screening in the Hispanic population, as currently advocated for African Americans.

According to the American College of Gastroenterology's colorectal cancer screening guideline, African‐Americans should start colorectal cancer screening at age 45, rather than age 50 because of the higher incidence and mortality of colorectal cancer as well as a greater prevalence of proximal or right‐sided polyps and cancer in this population.

Hispanics are more likely to be diagnosed with advanced stage colorectal cancer than non‐Hispanic whites and have a lower probability of survival after diagnosis after accounting for differences in age and stage, according to the American Cancer Society. Factors that may contribute to survival disparities include less access to and lower use of colorectal cancer screening tests and less access to timely and high‐quality treatment. Hispanics have lower colorectal cancer screening rates than any other minority group in the United States, according to "Cancer Facts and Figures for Hispanics/Latinos 2009‐2011."

A second study, "Racial Disparities in Diagnosis and Treatment Options," suggested that age at colorectal cancer diagnosis, location of tumor within the colon and survival from colorectal cancer varies significantly among race. Performed using tumor registries at Elmhurst Hospital Center, Elmhurst, New York, this retrospective review over eight years (2000‐2008) of 425 patients with colorectal cancer concluded that the likelihood of having colorectal cancer diagnosis before or after age 50 was significantly related to race.

According to the study, Asians were about twice as likely then non‐Asians to have colorectal cancer before age 50. Of 137 Asians with CRC, 36 (26.3 percent) were under the age 50, while of 288 non‐Asians with CRC, only 40 (13.9 percent) were under age 50. Whites were about one‐eighth less likely compared to non‐whites to have CRC before age 50. Of 91 whites with CRC, only three (3.3 percent) were under age 50, while among 334 non‐whites with CRC 73 (21.9 percent) were under age 50.

The study also found that the overall presence of right‐sided CRC vs. left‐sided CRC was significantly related to race. Hispanics were more likely than non‐Hispanics to have right‐sided CRC. Of 163 Hispanics with CRC, 52 (31.9 percent) had right‐sided CRC while of 262 non‐Hispanics with CRC, only 60 (22.9 percent) had right‐sided CRC. The overall unadjusted five‐year survival rate for Hispanics was better than non‐Hispanics (51.9 percent vs. 42.7 percent).

"These findings if validated by a larger study, can potentially affect medical guidelines regarding screening and treatment of colorectal cancer," said researcher Chinar Mehta, M.D.

Recent guidelines have debated routine screening for colorectal cancer in the elderly older than 75 years of age. Since minorities and women are often under‐represented in population‐based studies, a third CRC study unveiled today, "Gender Differences in the Colonoscopy Outcomes in Elderly African Americans," found that elderly African American females undergo colonoscopy more often than males and have a higher right‐sided incidence of advanced adenomas.

According to the findings, advanced adenoma was detected in 12 percent of the women and 17.4 percent of the men, while advanced adenoma was present on the right side in 71.3 percent of women and 70.5 percent of men. Colorectal cancer was found in 4.2 percent of women of which 51.5 percent were on the right side while 4.3 percent of men had colorectal cancer of which 47.1 percent were on the right side.

"The study found that African American women have a right‐sided preponderance for colorectal cancer in comparison to men," said researcher Manpreet Singh. M.D. "Also, a higher proportion of right‐sided lesions suggest that colonoscopy should be the preferred test for colorectal cancer screening in elderly African American women."