Mæhle et al. BMC Cancer 2010, 10:115 http://www.biomedcentral.com/1471-2407/10/115 R E S E A R C H A R T I C L E Open Access Birth length and weight as predictors of breast cancer prognosis Bjørn O Mæhle1,2*, Lars J Vatten3, Steinar Tretli3,4 Abstract Background: Birth size, and particularly birth length, is positively associated with breast cancer risk in adulthood. The objective of this study was to examine whether birth size is associated with survival among breast cancer patients. Methods: Information on birth size (weight, length and ponderal index (kg/length (m3)) was collected from birth archives for 331 breast cancer patients who were diagnosed at two university hospitals in Norway (Bergen and Trondheim). The patients were followed from the time of diagnosis until death from breast cancer, death from another cause, or to the end of follow-up, and birth size was related to survival, using Cox regression analysis. Results: Breast cancer patients with birth length ≥ 52 cm had nearly twice the risk of dying (hazard ratio, 1.92, 95% confidence interval, 1.09-3.41) from breast cancer compared to women with birth length less than 48 cm, after adjustment for place of birth and year of diagnosis. Similar analyses related to birth weight and ponderal index showed no clear association with breast cancer survival. Conclusions: Poorer outcome of breast cancer patients with high birth length may reflect effects of factors that stimulate longitudinal growth and simultaneously increase the risk of metastases and fatal outcome. It is possible that the insulin-like growth factor (IGF) system is involved in the underlying mechanisms. Background During the last two decades, it has been shown that birth size is positively associated with breast cancer risk later in life. Thus, birth weight, birth length, and head circumference have all shown positive associations with breast cancer risk in studies that employed measure- ments from birth records [1-3]. In a recent meta-analy- sis, it was suggested that birth length may be a better predictor than the other indicators of birth size [4], thus, the insulin like growth factor system (IGF) may somehow be implicated in the underlying mechanisms. Among factors measured in adulthood, it has been shown that body height is positively associated with breast cancer risk. High body mass index (BMI) is also associated with increased risk, but only among postme- nopausal women. Among premenopausal women, BMI appears to be inversely related to breast cancer risk [5-7]. * Correspondence: bjorn.mahle@gades.uib.no 1Section of Pathology, the Gade Institute, University of Bergen, Bergen, Norway Less attention has been given to these factors as pre- dictors of the prognosis among breast cancer patients. Nonetheless, it has been shown that adult obesity is adversely related to prognosis, both indicated as survival and mortality from breast cancer, and this effect appears to be equally strong for women with pre- and postme- nopausal disease [8]. On the other hand, there is no clear evidence that body height is associated with survi- val from breast cancer [9]. With regard to birth size, we are not aware of any study that has assessed the relation with breast cancer survival. In this study, we have therefore assessed whether birth size is associated with survival of subsequent breast can- cer, and in the analysis, we have adjusted for the influ- ence of known prognostic factors such as lymph node status and tumour diameter. Methods In order to have access to data on birth size, eligible breast cancer patients had to be born in Trondheim or Bergen, Norway. Therefore, we used data from the © 2010 Mæhle et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.