Higher Dairy Consumption Linked to Prostate Cancer Risk

SAN FRANCISCO—A new study supports the hypothesis that calcium consumption is associated with a greater risk of prostate cancer. June M. Chan, ScD, Department of Epidemiology, Harvard School of Public Health, presented the results at the 91^st Annual Meeting of the American Association for Cancer Research (AACR).

Dr. Chan and her colleagues at Harvard and Brigham and Women’s Hospital studied the relationship between dietary calcium and prostate cancer in the 20,885 men in the Physicians’ Health Study. At the beginning of the study, the subjects filled out a brief dietary questionnaire, which the investigators used to estimate their consumption of five dairy products, including milk, cheese, and ice cream. At 11 years of follow-up, 1,012 cases of prostate cancer were identified.

The results showed a moderate elevation in prostate cancer risk associated with higher intakes of dairy products and dairy calcium, adjusting for other risk factors such as age, smoking, exercise levels, and body mass index.

The study also showed that men who drank more than six glasses of milk a week had lower levels of vitamin D (1,25 dihydroxyvitamin D) than men who drank fewer than two glasses of milk a week. The researchers speculate that vitamin D may have protective effects on prostate cancer.

“For men concerned about prostate cancer, the study suggests a little caution, but it is far too early to recommend any extreme change in eating habits,” Dr. Chan cautioned. “More research is needed to confirm these findings and to clarify the underlying biological mechanisms.”

She noted that some data suggest that calcium may play a role in progression from local to metastatic disease. She and her colleagues will continue to investigate the role of calcium in tumor growth.