Colon cancer in Chile before and after the start of the flour fortification program with folic acid.

Background: Folate depletion is associated with an increased risk of colorectal carcinogenesis. A temporal association between folic acid fortification of enriched cereal grains and an increase in the incidence of colorectal cancer in the USA and Canada has, however, been recently reported.
Aim: To compare the rates of hospital discharges owing to colon cancer in Chile before and after the start of the mandatory flour fortification program with 220 microg of synthetic folic acid/100 g of wheat flour.
Methods: Cancer and cardiovascular hospital discharge rates were compared using rate ratios between two study periods, 1992-1996, before folic acid fortification and 2001-2004, after the flour fortification with folic acid was established in the country. Standard errors of the log rate ratio to derive confidence intervals, and to test the null hypothesis of no difference, were calculated.
Results: The highest rate ratio between the two periods was for colon cancer in the group aged 45-64 years (rate ratio: 2.6, confidence interval: 99% 2.93-2.58) and in the 65-79 years (rate ratio: 2.9, confidence interval: 99% 3.25-2.86).
Conclusion: Our data provide new evidence that a folate fortification program could be associated with an additional risk of colon cancer.