Research Article: Birth Size and Breast Cancer Risk: Re-analysis of Individual Participant Data from 32 Studies

Date Published: September 30, 2008

Publisher: Public Library of Science

Author(s): Isabel dos Santos Silva, Bianca De Stavola, Valerie McCormack, Hans-Olov Adami

Abstract: Isobel dos Santos Silva and Bianca De Stavola and colleagues reanalyzed individual participant data from 32 published and unpublished studies to obtain precise estimates of the association between birth size and breast cancer risk.

Partial Text: In 1990 Trichopoulos [1] suggested that prenatal exposure to high levels of pregnancy oestrogens
might affect the risk of breast cancer. This hypothesis, which has since evolved to include
other in utero hormonal and biological factors [2], sparked a considerable amount of research on
the prenatal origins of breast cancer, relying mainly on birth size measures as indirect
markers of the in utero environment. Published estimates of the strength of the association
between birth size and breast cancer, however, have been far from consistent [3–33], and several unanswered questions remain,
including uncertainty regarding the magnitude and shape of the association as well as the
extent to which it may be mediated, confounded, and/or modified by known breast cancer risk
factors.

We analysed individual participant data on over 22,000 women with breast cancer from 32
epidemiological studies of the association between birth size and breast cancer. This pooled
analysis provided evidence of moderate positive trends in the risk of breast cancer among
studies based on birth records, with risk increasing with increasing birth weight, length,
and head circumference. Source of birth size data was identified as the main source of
between-study heterogeneity, with positive associations of birth size with breast cancer
risk found only in data from birth records and, to a lesser extent, in data from parental
recalls when the women were aged 6–7 y, but not in data from self-reports or
maternal recalls when the women were adults.

Source:

http://doi.org/10.1371/journal.pmed.0050193

 

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