Date Published: December 14, 2009
Publisher: Public Library of Science
Author(s): Jacqueline M. Cohen, Jennifer A. Hutcheon, Sofi G. Julien, Michel L. Tremblay, Rebecca Fuhrer, Adrian V. Hernandez. http://doi.org/10.1371/journal.pone.0008237
Abstract: An association between insufficient milk supply, the inability of a mother’s breast milk to provide sufficiently for her infant, and breast cancer has been suggested by observations in animal models. To determine if an association has been reported in epidemiological studies of human breast cancer, a systematic review of the literature has been conducted. We also sought to identify the methodological limitations of existing studies to guide the design of any future prospective studies in this field.
Partial Text: In North America, breast cancer is the second leading cause of cancer-related death in women . Because of the relatively lower percentage of breast cancer cases at younger ages (4% of cases and 2% of all breast cancer deaths among Canadian women ages 20–39 ), young women are not typically screened for breast cancer. However, a systematic review of long term survival (10+ years) after breast cancer found that younger age usually entails a more deadly cancer . Further, epidemiological studies have shown that breast cancer diagnosed in close proximity to last birth shows poorer prognosis .
The combined searches of Berrino et al. and our group (i.e. 1966–2008) yielded 120 articles for the full-text secondary screen (Figure 1). Seven studies were identified in this secondary screen that provided estimates of the effect of insufficient milk on breast cancer risk (Table 2) –. The primary reason for exclusion of studies during the full-text screen was that they did not provide data on our primary research question. Few studies asked subjects why they had discontinued breastfeeding or if they had experienced difficulties breastfeeding. Three studies were excluded in the secondary screen which reported in their methods that they had asked study subjects about reasons for breastfeeding cessation in the interview, but did not report any data related to insufficient milk supply or breastfeeding difficulties in general –.