Wednesday, March 11, 2009
WEDNESDAY, Mar. 11 (HealthDay News) -- Folic acid supplementation may be associated with a higher risk of prostate cancer, and different definitions of "lead time" in studies on screening with prostate-specific antigen (PSA) can affect their outcome, according to two reports published online Mar. 10 in the Journal of the National Cancer Institute.
In the first study, Jane C. Figueiredo, Ph.D., of the University of Southern California in Los Angeles, and colleagues analyzed data from 643 men in a polyp prevention study who were randomized to receive placebo or folic acid supplementation. The estimated probability of being diagnosed with prostate cancer over 10 years was 9.7 percent in the treatment group and 3.3 percent in the placebo group, for an age-adjusted hazard ratio of 2.63 percent.
In the other study, Gerrit Draisma, Ph.D., of the University Medical Center in Rotterdam, the Netherlands, and colleagues used three models of prostate cancer progression and detection that were calibrated to Surveillance, Epidemiology, and End Results incidence data to estimate lead times and overdiagnosis associated with PSA screening. Estimated mean lead times varied from 5.4 to 6.9 years, and overdiagnosis ranged from 23 to 42 percent of all cancers found by PSA testing, the researchers report.
"Using the folate supplementation trial as an example, it is not unreasonable to assume that optimal levels of folate are associated with more fidelity in DNA replication and thus a lower risk of spontaneous mutations, but high folate may also support more rapid cell growth and promote carcinogenesis in previously initiated cells. It is safe to conclude that cancer prevention is not going to be as simple as recommending high-dose micronutrient supplements for middle-aged and older adults," write the authors of an editorial accompanying the Figueiredo study.
In the Figueiredo study, Wyeth provided study agents for the underlying clinical trial, and one of the study co-authors is a consultant for Prozen, Inc.
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