Higher parity and shorter breastfeeding duration: association with triple-negative phenotype of breast cancer.
Subject: Breast feeding (Research)
Breast cancer (Research)
Parity (Obstetrics) (Research)
Author: Lording, Ros
Pub Date: 03/01/2011
Publication: Name: Breastfeeding Review Publisher: Australian Breastfeeding Association Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2011 Australian Breastfeeding Association ISSN: 0729-2759
Issue: Date: March, 2011 Source Volume: 19 Source Issue: 1
Topic: Event Code: 310 Science & research
Geographic: Geographic Scope: United States Geographic Code: 1USA United States
Accession Number: 256365953
Full Text: Triple-negative breast cancers (BCs) are aggressive cancers distinguished by the absence of oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2). Triple-negative BCs are more common among carriers of BRCA1 germ line mutation and among premenopausal African--American women, and they have also been associated with shorter lifetime duration of breastfeeding. In theory, the combination of increased parity and shorter breastfeeding duration might increase the odds of triple-negative BC because an expanded progenitor cell population within the breast tissue might fail to completely differentiate postpartum.

This study aimed to identify an association between parity and breastfeeding duration and the frequency of triple-negative BCs. A second aim was to examine these associations by ethnicity after adjusting for other potential risk factors for triple-negative BC.

The study population comprised a consecutive case series of 2473 women treated for invasive breast cancer at a cancer centre in Texas. Data on breast cancer phenotype (triple-negative BC versus non-triple-negative BC) and demographic and clinical risk factors were collected from electronic medical records and de-identified before statistical analysis.

Analysis revealed that triple-negative BC was associated with shorter duration of breastfeeding per child and higher parity, compared to non-triple-negative BC. Using multivariate logistic regression, triple-negative BC was independently associated with higher parity (OR 2.76 if [greater than or equal to]3 live births or OR 1.89 if [less than or equal to]2 live births compared to nulliparae), breastfeeding duration (OR 0.55 if >2 months per child and OR 0.58 if [less than or equal to]2 months per child compared to none), African-American ethnicity (OR 2.10) and younger age at diagnosis (OR 3.02 if [less than or equal to]40 years compared to >60 years).

The authors conclude that higher parity and the absence or short duration of breastfeeding were independently associated with triple-negative BC among women with invasive BC. Furthermore, any duration of breastfeeding was associated with reduced risk of triple-negative BC, with the odds of this phenotype decreasing with increased breastfeeding duration.

Shinde SS, Forman MR, Kuerer HM, Yan K, Peintinger F, Hunt KK, Hortobagyi GN, Pusztai L, Symmans WF 2010, Cancer 116(21): 4933-43.

RL: Ros Lording BA BSW(Hons) MPH Cert IV Breastfeeding Education (Counselling) Cert IV Breastfeeding Education (Community)
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