Studies show role of age, gender, race and weight on cancer risk and treatment

WASHINGTON, D.C. (May 21, 2007) — While cancer has been studied extensively to determine the major contributing factors for risk and ultimate outcome, many variables still remain and doctors are puzzled by new cases that do not fit "old" protocol. Research presented today at Digestive Disease Week® 2007 (DDW®) demonstrates improved results in determining these risks, including the relative "weight" of being heavy on risk for colon cancer; possible risk of cancer surgery among elderly individuals; and how race determines incidence as well as treatment decisions. DDW is the largest international gathering of physicians and researchers in the fields of gastroenterology, hepatology, endoscopy and gastrointestinal surgery.

"Drilling down into clinical trials data for different types of patients can lead to varying and important conclusions," said Marcia R. Cruz-Correa, M.D., Ph.D., Associate Professor of Medicine and Biochemistry, University of Puerto Rico Comprehensive Cancer Center. "In these instances, management of risk factors for colon cancer and treatment decisions for a particular sub-group of patients can be influenced by these analyses."

Hepatocellular carcinoma (HCC), a cancer of cells in the liver, is on the rise in part due to the high prevalence of chronic hepatitis C infection, which increases the risk for the disease. Surgery is the only potential curative treatment for HCC and this study sought to determine the patterns of use for this treatment.

Researchers from the University of Michigan Health System in Ann Arbor, Mich., and the Johns Hopkins University School of Medicine in Baltimore, Md., reviewed data of all HCC patients submitted to the Surveillance, Epidemiology and End Results (SEER) National Cancer Institute registry between 1998 and 2003. A total of 14,902 patients with HCC were included in the analysis, 20 percent of whom underwent surgical therapy (8.5% resection, 6.1% ablation and 4.9% transplant). The use of surgery to treat HCC increased five percent per year during that timeframe.

After reviewing the data, investigators found that racial and regional disparities can affect whether or not liver cancer patients receive important, life-saving surgical treatment. There were geographic differences in the use of surgery for HCC, ranging from eight percent in Georgia to 31 percent in Alaska and Hawaii. Younger women with a single, small tumor were most likely to undergo surgery. African Americans were 25 percent less likely to receive surgical therapy than white patients, while Asian patients were 27 percent more likely to receive it. Interestingly, people who lived in densely populated counties with higher rates of unemployment were not as likely to be offered surgery to treat HCC.

"Significant racial and regional differences exist in the utilization of surgical therapy for hepatocellular carcinoma," said Christopher J. Sonnenday, M.D., of the University of Michigan Health System in Ann Arbor and lead author of the study. "Possible explanations for this could be that patients are refusing treatment, that they are unable or unwilling to seek therapy outside of their immediate community, or perhaps they are not being offered therapy at all by their physicians. Further investigation is needed to understand the reason for these differences to ensure that surgery is available to those who need it, as it is really the only potential cure for HCC."

Dr. Sonnenday will present this study on Monday, May 21, at 8:30 a.m. in Room 202A.

Research shows that the prevalence of obesity is rising, causing an increase in heart disease and diabetes, among other conditions, but evidence has not yet been established linking obesity to precancerous lesions in the colon called polyps. This study evaluated the effect of gender and obesity on the prevalence of colorectal polyps in a diverse population.

Body mass index (BMI) was calculated for 581 patients enrolled in the study and classified as normal (BMI 18-24.0), overweight (BMI 25-29.9) or obese (BMI greater than or equal to 30).

Fifty-two percent of patients were Hispanic, 26 percent Asian, 14.1 percent African American and 7.2 percent Caucasian. More than half of the patients (61%) were women, with the average age of the group (approximately 58 years) and mean BMI (approximately 27) the same for both men and women. During the screening, Dr. Fritz Francois and colleagues found polyps in 14.5 percent of patients, with 80 percent being advanced neoplasms, or large polyps. Overall, women had fewer polyps and fewer advanced neoplasms than men (12.4 vs. 17.7% and 5.7 vs. 17.5%, respectively).

However, for the 207 overweight and 111 obese women, the prevalence of polyps increased to nearly equal to that of men (13.0 vs. 14.6% and 18.6 vs. 18.0%, respectively). The number of advanced neoplasms doubled in this group of women and was comparable to that of men as well. After controlling for age and race, the likelihood of having a polyp of any size was significantly lower in normal weight women compared to overweight and obese women.

"Obesity puts people at risk for a number of different diseases and the results of this study show that obese women should add colon cancer to that list," said Fritz Francois, M.D., of the New York University Medical Center in New York, N.Y. and senior author of the study. "Further research is needed to confirm these findings and to understand how obesity contributes to the formation of polyps."

Dr. Francois and his team will present this study on Monday, May 21, at 10:42 a.m. in Room 150.

Rates of colorectal cancer in elderly people are increasing, but there has been relatively little study of this disease in the "oldest" of the old or very elderly patients. This study focused on outcomes data to determine how an aggressive surgical approach impacted the long-term survival of patients aged 85 and older.

In the study, 2,237 patients with colorectal cancer were prospectively enrolled at St. Vincent's University Hospital in Dublin, Ireland (90 were age 85 or older; 2,147 were less than 85 years of age) and followed to determine long-term survival. There were more women in the very elderly group compared to the under 85 cohort (66% vs. 47%) and a greater proportion of right sided tumors. However, operative rates (91% vs. 94%) and tumor resection rates (86% vs. 91%) were similar in both groups. No patient in the elderly group received chemotherapy. Death within 30 days of diagnosis was increased in the very elderly patients (11% vs. 4%). However, relative survival in the very elderly, beyond this early period, was more similar to the general population, with 50 percent surviving at least two years. While elderly patients are more likely to die from colorectal cancer than their younger counterparts, many have good relative life expectancy after surgery.

"Surgery for colon cancer can prolong life and improve quality of life for both young patients and even the 'oldest' of old patients," said Glen Doherty, M.D., of the Centre for Colorectal Disease, St. Vincent's University Hospital and lead author of the study. "When appropriate, very elderly patients should be offered an aggressive approach to treating colon cancer, including surgery."

Dr. Doherty will present this study on Tuesday, May 22, at 3:15 p.m. in Room 158.

The incidence of colorectal cancer varies according to race, but little is known about how different races are affected by specific types of the disease. Proximal colon cancer is the most common type of colon cancer, occurring in the proximal portion of the large intestine closest to the small intestine.

Ananya Das, M.D., analyzed the Surveillance, Epidemiology and End-Results (SEER) database of the National Cancer Institute and identified all patients with confirmed, invasive primary colorectal cancer between 1973 and 2003. Gender, race and sub-site specific, age-adjusted incidence rates were calculated.

Overall colon cancer and proximal colon cancer rates gradually declined during the 30-year period in African Americans and Caucasians and men and women. But since the mid-1990s, African Americans, and African American men in particular, have experienced a significant and consistent rise in proximal colon cancer. It has been proposed that cancers occurring at different sub-sites in the colon may have different underlying causes, and that colonoscopy is a better tool for screening for proximal colon cancer than is flexible sigmoidoscopy. In a colonoscopy, a long flexible lighted tube is inserted into the rectum and slowly guided in to view the entire colon, while in a sigmoidoscopy, only the first third of the colon is viewable.

"These results should be used to plan for screening interventions among the African American population to include complete colonoscopies," said Dr. Das of the Mayo Clinic Scottsdale in Arizona and senior author of the study. "Further epidemiological research is needed to identify site-specific risk factors for proximal colon cancers."

Dr. Das will present this study on Monday, May 21, at 10:54 a.m. in Room 150.

Digestive Disease Week® (DDW®) is the largest international gathering of physicians, researchers and academics in the fields of gastroenterology, hepatology, endoscopy and gastrointestinal surgery. Jointly sponsored by the American Association for the Study of Liver Diseases (AASLD), the American Gastroenterological Association (AGA) Institute, the American Society for Gastrointestinal Endoscopy (ASGE) and the Society for Surgery of the Alimentary Tract (SSAT), DDW takes place May 19-24, 2007 in Washington, D.C. The meeting showcases more than 5,000 abstracts and hundreds of lectures on the latest advances in GI research, medicine and technology.