Here are just a few of the studies highlighted during the annual American Association for Cancer Research (AACR) International Conference on Frontiers in Cancer Prevention, held October 27-30 in National Harbor, Maryland.
Current HPV Vaccines Less Beneficial to African American Women
The most frequent cervical cancer–causing human papillomavirus (HPV) subtype found in African American women is not protected by currently available HPV vaccines, according to one study presented at the conference.
Researchers say they need to replicate these findings in larger cohorts, but they suggest that current HPV vaccines, which target subtypes 16 and 18, will be less beneficial for African American women than non-Hispanic white women, according to Cathrine Hoyo, PhD, MPH, associate professor in the obstetrics and gynecology department at Duke University School of Medicine in Durham, North Carolina.
Dr. Hoyo says that African American women are approximately 20% more likely to develop cervical cancer and almost twice as likely to die from the disease as their non-Hispanic white counterparts. She and colleagues found a much lower prevalence of HPV-16 and -18 in advanced, precancerous cervical abnormalities (CIN2 and CIN3) in African American women. Instead, CIN2 and CIN3 harbored HPV-31, -35, -45, -56, -58, -66, and -68, all of which are linked to cervical cancer. A vaccine that targets 9 HPV subtypes is currently being tested in phase 3 clinical trials.
That vaccine may be better for African American women because it targets 3 of the cervical cancer HPV subtypes that appear to be prevalent in African American women with CIN2 and CIN3. Still, because the new vaccine does not include HPV- 35, -66, and -68, more work needs to be done, Dr. Hoyo says.
Dr. Hoyo and her colleagues are enrolling women who are undergoing a colonoscopy following an abnormal Pap test in the Cervical Intraepithelial Neoplasia Cohort Study in an effort to identify markers that distinguish early CIN from advanced CIN. They have evaluated the HPV subtypes present in the CIN of 572 participants, including 280 African American women and 292 non-Hispanic white women.
Sedentary Men at Risk for Colorectal Adenoma Recurrence
In another study, scientists found that men who spent the most time being sedentary are at greatest risk for recurrence of colorectal adenomas, which are benign precursors to colorectal cancers.
Christine Sardo Molmenti, PhD, MPH, postdoctoral fellow in the department of epidemiology at Columbia University Mailman School of Public Health in New York City, and colleagues performed a pooled analysis from 2 randomized phase 3 clinical trials performed at the University of Arizona Cancer Center and the Mel and Enid Zuckerman College of Public Health, both in Tucson, Arizona. All participants had one or more colorectal adenomas removed during a colonoscopy in the 6 months prior to enrollment. They completed a questionnaire about their leisure, recreational, household, and other activities.
The researchers found no correlation between type of activity and adenoma recurrence, but they did find that men who reported spending more than 11.38 hours per day being sedentary, which included working at a computer and reading, were 45% more likely to experience colorectal adenoma recurrence than men who spent fewer than 6.9 hours a day being sedentary. No link was found between sedentary time and adenoma recurrence in women.
Short-Ended Chromosomes Increase Risk for Aggressive Prostate Cancer
A third study presented found that men with short-ended chromosomes in the immune cells in their blood were at increased risk for aggressive prostate cancer compared with men with long-ended chromosomes in blood immune cells. The finding is important because, currently, scientists have no way of predicting which men are at risk for developing the aggressive form of the disease.
The research, led by Elizabeth Platz, ScD, MPH, a professor in the department of epidemiology at Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland, indicates that the length of telomeres in blood leukocytes could be a biomarker for determining risk of aggressive prostate cancer. Telomeres are often shortened in cancers, making the chromosomes less stable and more prone to damage, Dr. Platz says.
She and her colleagues analyzed DNA from immune cells (leukocytes) isolated from blood samples given from 1993 to 1995 by men enrolled in Harvard's Health Professionals Follow-Up Study. They studied 441 men who later developed prostate cancer, with a mean time from blood draw to diagnosis of 3 years, and 421 men who did not develop the disease during follow-up. The results showed that among the men who developed prostate cancer, those with the shortest telomeres in their leukocytes at blood draw were more than twice as likely to have developed aggressive disease as those who had the longest telomeres.
Among men who were smokers or former smokers, researchers also discovered that those with the shortest telomeres in their blood leukocytes were more than 4 times as likely to have developed aggressive prostate cancer.
Dr. Platz says she and her colleagues do not yet know the reason for the association but that telomere length in blood leukocytes possibly could predict the risk of many different forms of cancer.