Dietary folates and cancer risk in a network of case-control studies.
BACKGROUND
Folate deficiency leads to DNA damage and inadequate repair, caused by a decreased synthesis of thymidylate and purines. We analyzed the relationship between dietary folate intake and the risk of several cancers.


METHODS
The study is based on a network of case-control studies conducted in Italy and Switzerland in 1991-2009. The odds ratios (ORs) for dietary folate intake were estimated by multiple logistic regression models, adjusted for major identified confounding factors.


RESULTS
For a few cancer sites, we found a significant inverse relation, with ORs for an increment of 100 μg/day of dietary folate of 0.65 for oropharyngeal (1467 cases), 0.58 for esophageal (505 cases), 0.83 for colorectal (2390 cases), 0.72 for pancreatic (326 cases), 0.67 for laryngeal (851 cases) and 0.87 for breast (3034 cases) cancers. The risk estimates were below unity, although not significantly, for cancers of the endometrium (OR = 0.87, 454 cases), ovary (OR = 0.86, 1031 cases), prostate (OR = 0.91, 1468 cases) and kidney (OR = 0.88, 767 cases), and was 1.00 for stomach cancer (230 cases). No material heterogeneity was found in strata of sex, age, smoking and alcohol drinking.


CONCLUSIONS
Our data support a real inverse association of dietary folate intake with the risk of several common cancers.
Department of Epidemiology, Istituto di Ricerche Farmacologiche 'Mario Negri', Milan. Electronic address: alessandra.tavani@marionegri.it.
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Tavani
Department of Epidemiology, Istituto di Ricerche Farmacologiche 'Mario Negri', Milan.
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Malerba
Department of Epidemiology, Istituto di Ricerche Farmacologiche 'Mario Negri', Milan.
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Pelucchi
Unit of Epidemiology and Biostatistics, Centro di Riferimento Oncologico, Aviano (Pordenone), Italy.
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Dal Maso
Unit of Epidemiology and Biostatistics, Centro di Riferimento Oncologico, Aviano (Pordenone), Italy.
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Zucchetto
Unit of Epidemiology and Biostatistics, Centro di Riferimento Oncologico, Aviano (Pordenone), Italy.
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Serraino
Cancer Epidemiology Unit and Registre Vaudois des Tumeurs, Institut universitaire de médecine sociale et préventive, Lausanne, Switzerland.
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Levi
Unit of Epidemiology, Istituto Tumori 'Fondazione Pascale', Naples, Italy.
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Montella
International Agency for Research on Cancer, Lyon, France.
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Franceschi
Department of Statistics, Unit of Biostatistics and Epidemiology, University of Milano-Bicocca, Milan.
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Zambon
Department of Epidemiology, Istituto di Ricerche Farmacologiche 'Mario Negri', Milan; Department of Clinical Sciences and Public Health, University of Milan, Milan, Italy.
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La Vecchia
D016022:Case-Control Studies; D004032:Diet; D005492:Folic Acid / Q000008:administration & dosage*; D006801:Humans; D009369:Neoplasms / Q000453:epidemiology*; D012307:Risk Factors; D013624:Taiwan
D005492:Folic Acid