Researchers at the School of Medicine have discovered that the wilting broccoli in dining halls across campus is more friend than foe, at least for men: Studies show that eating broccoli reduces the risk of aggressive prostate cancer by 40 percent.
The study, released in the Journal of the National Cancer Institute last month, found that those who eat cruciferous vegetables, such as broccoli and cauliflower, have a lower risk of developing prostate cancer — but only the fast-moving, aggressive form of the disease. The team, led by postdoctoral fellow Victoria Kirsh, analyzed 29,000 dietary habit questionnaires, controlling for external factors such as race, family history and body mass index.
“We didn’t see any overall correlation, but the protective effect occurred only for the more aggressive form of prostate cancer, not the slower-growing form,” Kirsh said.
The reason for this discrepancy is not yet known, though Kirsh speculates that the two forms of prostate cancer might very well have different causes and risk factors.
Cruciferous vegetables have already been shown to be particularly anticarcinogenic, contributing to their effectiveness in preventing aggressive prostate cancer. Other cruciferous vegetables include cabbage, Brussels sprouts, turnips, kale and bok choy.
This study is significant because it directly connects eating vegetables to a lower risk of developing a certain disease, said Susan Mayne, a professor of epidemiology and public health. Though doctors generally tell patients at risk for prostate cancer to modify their diet, there has not been solid research supporting specific dietary guidelines.
Mayne said that the study is reliable because it controls for more lifestyle factors than many others do. For instance, because men with healthier habits may be more likely to be screened for cancer, studies using random samples may inadvertently suggest that a diet rich in vegetables actually increases cancer risk. But in this study, the scientists pre-screened their subjects in a randomized but consistent manner, controlling for discrepancies that erratic screening practices can cause, Kirsh said.
William Kevin Kelly, director of clinical research services at Yale Cancer Center, said that the findings of this study are promising, but have limited clinical applications for patients.
“There are a lot of dietary restrictions that are recommended for prostate cancer,” Kelly said. “But is there any conclusive evidence that it delays or prevents prostate cancer? No.”
Vegetables aside, Mayne said that the greatest hope for those with prostate cancer — 218,000 men will be diagnosed with the disease in 2007 — lies in finding concrete preventive strategies for the disease.