Increased cancer cell proliferation in prostate cancer patients with high levels of serum folate

BACKGROUND A recent clinical trial revealed that folic acid supplementation is associated with an increased incidence of prostate cancer (Figueiredo et al., J Natl Cancer Inst 2009; 101(6): 432–435). As tumor cells in culture proliferate directly in response to available folic acid, the goal of our study was to determine if there is a similar relationship between patient folate status, and the proliferative capacity of tumors in men with prostate cancer. METHODS Serum folate and/or prostate tissue folate was determined in 87 randomly selected patients undergoing surgery for prostate cancer, and compared to tumor proliferation in a subset. RESULTS Fasting serum folate levels were positively correlated with prostate tumor tissue folate content (n = 15; r = 0.577, P