Women Born As Big Babies More Susceptible To Breast Cancer

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Main Category: Breast Cancer
Also Included In: Pediatrics / Children's Health;  Women's Health / Gynecology
Article Date: 30 Sep 2008 - 9:00 PST

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Women who were born as big babies, particularly if they were longer in length, are more susceptible to breast cancer said UK researchers after re-analysing data from published and unpublished studies.

The analysis was the work of researchers at the London School of Hygiene and Tropical Medicine and is published in PLoS Medicine.

Isabel dos Santos Silva, Professor of Epidemiology at the School, led the research to obtain more precise estimates of the extent to which birth size and risk of breast cancer later in life were linked, since findings from epidemiological studies have been inconsistent on this.

They reviewed 32 studies covering 22,058 cases of breast cancer among more than 600,000 women living mostly in the developed world.

Pooling data from studies that drew birth size information from official birth records rather than participant self reports (notoiously less reliable as sources of historical data), the researchers found birth weight was positively associated with breast cancer risk to the extent that a 0.5 kg (1.1 lbs) increment in birth weight was linked to an estimated 7 per cent increase in risk of breast cancer.

Further analysis of data from official records also showed a positive link between breast cancer risk in adulthood with body length and head circumference at birth, with body length being the strongest predictor. The figures did not change much when the researchers took into account established breast cancer risk factors.

"Our study indicates that birth size is a marker of susceptibility to breast cancer in adulthood, at least in developed countries," said Silva, adding that the link was largely independent of known risk factors and that:

"Little is known on how the pre-natal environment may affect breast cancer risk later in life."

Silva said more research was needed "to unravel the biological mechanisms underlying the birth size - breast cancer association".

Pagona Lagiou and Dimitrios Trichopoulos of Harvard University School of Public Health, who were not involved in the study, said in an accompanying comment that these findings show:

"The strongest evidence yet that birth size is a critical determinant of breast cancer risk in adult life."

"Birth Size and Breast Cancer Risk: Re-analysis of Individual Participant Data from 32 Studies."
Isabel dos Santos Silva, Bianca De Stavola, Valerie McCormack, Collaborative Group on Pre-Natal Risk Factors and Subsequent Risk of Breast Cancer.
PLoS Medicine Vol. 5, No. 9, e193
doi:10.1371/journal.pmed.0050193

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Source: Public Library of Science.

Written by: Catharine Paddock, PhD.


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