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 < 0.03). Mean serum folate was 62.6 nM (7.5-145.2 nM), 39.5% of patients used supplements containing folic acid (n = 86). The top quartile of patients had serum folates above 82 nM, six times the level considered adequate. Of these, 48% reported no supplement use. Among 50 patients with Gleason 7 disease, the mean proliferation index as determined by Ki67 staining was 6.17 ± 3.2% and 0.86 ± 0.92% in the tumors from patients in the highest (117 ± 15 nM) and lowest (18 ± 9 nM) quintiles for serum folate, respectively (P < 0.0001). CONCLUSIONS: Increased cancer cell proliferation in men with higher serum folate concentrations is consistent with an increase in prostate cancer incidence observed with folate supplementation. Unexpectedly, more than 25% of patients had serum folate levels greater than sixfold adequate. Nearly half of these men reported no supplement use, suggesting either altered folate metabolism and/or sustained consumption of folic acid from fortified foods.
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 patientfolate 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 < 0.03). Mean serum folate was 62.6 nM (7.5-145.2 nM), 39.5% of patients used supplements containing folic acid (n = 86). The top quartile of patients had serum folates above 82 nM, six times the level considered adequate. Of these, 48% reported no supplement use. Among 50 patients with Gleason 7 disease, the mean proliferation index as determined by Ki67 staining was 6.17 ± 3.2% and 0.86 ± 0.92% in the tumors from patients in the highest (117 ± 15 nM) and lowest (18 ± 9 nM) quintiles for serum folate, respectively (P < 0.0001). CONCLUSIONS: Increased cancer cell proliferation in men with higher serum folate concentrations is consistent with an increase in prostate cancer incidence observed with folate supplementation. Unexpectedly, more than 25% of patients had serum folate levels greater than sixfold adequate. Nearly half of these men reported no supplement use, suggesting either altered folate metabolism and/or sustained consumption of folic acid from fortified foods.
Authors: Regan L Bailey; James L Mills; Elizabeth A Yetley; Jaime J Gahche; Christine M Pfeiffer; Johanna T Dwyer; Kevin W Dodd; Christopher T Sempos; Joseph M Betz; Mary Frances Picciano Journal: Am J Clin Nutr Date: 2010-06-23 Impact factor: 7.045
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Authors: V S Khoo; A Pollack; D Cowen; D L Joon; N Patel; N H Terry; G K Zagars; A C von Eschenbach; M L Meistrich; P Troncoso Journal: Prostate Date: 1999-11-01 Impact factor: 4.104
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