No Association Between Fat, Protein, and Meat Consumption and Kidney Cancer
There is no association between consumption of fat, protein, or meat and kidney cancer, according to a pooled analysis of prospective studies.
The incidence of renal cell cancer is increasing worldwide, but the cause of the increase remains obscure. Epidemiological studies have produced inconsistent results with respect to an association between consumption of fat, protein, and meat and kidney cancer risk.
In the current study, Jung Eun Lee, Sc.D., of the Brigham and Women's Hospital and Harvard Medical School in Boston and colleagues analyzed data from 13 prospective studies that enrolled 530,469 women and 244,483 men. All study participants filled out food questionnaires when they enrolled in the study. A total of 1,478 renal cancer cases were identified in the study populations during follow-up.
When the researchers compared the fat, protein and meat intakes of the participants who developed kidney cancer with those who did not develop the disease, they found no association with fat, protein, or meat intake after considering the influence of other known kidney cancer risk factors.
"Our data do not support the hypotheses that intakes of fat, protein, or meat from animal sources are associated with an increased risk of renal cell cancer," the authors conclude.
In an accompanying editorial, Victor Kipnis, Ph.D., of the National Cancer Institute in Bethesda, Md., and Laurence S. Freedman, Ph.D., of the Gertner Institute for Epidemiology and Health Policy Research in Tel Hashomer, Israel, discuss the impact of measurement error on studies that assess the association between diet and cancer. Even when researchers make substantial effort to account for measurement error, as Lee and colleagues did, it can still be a problem.
"Continued caution is required when interpreting associations, or the lack thereof, between dietary factors and disease," the editorialists conclude. "Only when multiple studies with different designs in diverse populations produce consistent, robust results, can the evidence regarding an association be sufficiently persuasive."
Mammography Use and Accuracy Not Associated with Breast Cancer Risk in Overweight and Obese Postmenopausal Women
Patterns of mammography use and mammography accuracy are not the primary reasons for the increased risk of breast cancer or advanced breast cancer diagnosis in overweight and obese postmenopausal women relative to normal weight women in a large prospective study.
Obese and overweight women are at greater risk of postmenopausal breast cancer. The reasons for that increased risk are not understood.
To determine whether decreased mammography accuracy or use among overweight and obese women influenced breast cancer risk, Karla Kerlikowske, M.D., of the San Francisco Veterans Affairs Medical Center and colleagues analyzed data from seven mammography registries that participate in the Breast Cancer Surveillance Consortium. A total of 287,115 postmenopausal women not using hormone therapy underwent 614,562 mammography exams during 1996�, and 4,446 women were diagnosed with breast cancer.
Overweight and obese women had a statistically significantly increased rate of breast cancer and advanced breast cancer, compared with normal weight women, after taking into account patterns of mammography use and accuracy. Higher rates of advanced-stage breast cancer were observed in overweight and obese women compared with normal weight women for any given length of time between screening examinations, suggesting that mammography exposure is not a major influence on increased risk of advanced disease.
"Our results suggest that postmenopausal women who are overweight or obese--a large proportion in the United States (58% of women in our study)--should be encouraged to lose weight and to undergo routine screening mammography, two factors that may decrease the number of women who are diagnosed with advanced disease," the authors conclude.
Contact: Steve Tokar, firstname.lastname@example.org, (415) 221-4810 x5202
Reduced DNA Methylation Associated with Poorer Survival in Colon Cancer Patients
DNA hypomethylation in colon cancer tumors is associated with poorer patient survival.
DNA hypomethylation activates silenced genes and is associated with genomic instability and the development of colorectal cancer.
To find out if hypomethylation is associated with patient survival in colon cancer, Shuji Ogino, M.D., Ph.D., of Dana-Farber Cancer Institute and Harvard Medical School in Boston and colleagues measured the level of tumor DNA methylation in a section of DNA containing repetitive sequences that are normally methylated, called long interspersed nucleotide element-1 (LINE-1), and compared it with survival in 643 patients. Patients were identified from two prospective cohorts, the Nurses' Health Study and the Health Professionals Follow-up Study.
Patients whose tumor DNA had less methylation had a statistically significant increase in colon cancer-specific mortality and overall mortality.
"The results from this large prospective cohort study suggest that genome-wide DNA hypomethylation as measured in LINE-1 is independently associated with poor survival among patients with colon cancer," the authors conclude.
Contact: Bill Schaller, William_Schaller@dfci.harvard.edu, (617) 632-5357
Also in the November 25 JNCI: