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Taking folate in pregnancy and risk of maternal breast cancer

BMJ 2004; 329 doi: https://doi.org/10.1136/bmj.329.7479.1375 (Published 09 December 2004) Cite this as: BMJ 2004;329:1375

Rapid Response:

Misleading the international media

Sir, the preliminary report on possible association of folic acid and risk of maternal breast cancer published in BMJ yields poor results that are even not statistically significant(1). The Hazard Ratio (HR) of 2.02 is based on only eight cases in the group of women who took tablets of 5 mg folate. When you control so many variables as the authors of this report did (maternal age, smoking height, weight, social class, systolic blood pressure, parity and gestational age) one need explicitly to state the reasons for such adjustment. The only justification to control for so many variables is if the outcome (breast cancer) is strongly associated both with the exposure (folic acid) and the control variable. In addition, controlling for so many variables when we have only eight (8) cases could produce spurious association even if such does not exist.

It is very likely that this finding is by chance only, as the authors concluded by it self.

The problem is that this report is widely communicated in the international press (2). This could mislead the public and discourage future mothers that there is really risk of taking folic acid over the pregnancy.

It is preferable such reports that attracts the attention of the media to be based on sound methodology and valid conclusions. This was not the case with this report.

1.Charles D, Ness AR, Campbell D, Davey Smith G, Hall MH. Taking folate in pregnancy and risk of maternal breast cancer. BMJ 2002;329:1375- 1376.

2.Times online. Breast cancer fear for pregnant women over folic acid tablets. http://www.timesonline.co.uk/article/0,,2-1397214,00.html

Respectufly submitted,

Vladimir Lazarevik MD MPH

Competing interests: None declared

Competing interests: No competing interests

10 December 2004
Vladimir Lazarevik
Health Information Specialist
Medical Faculty, Department of Social Medicine Skopje Macedonia