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Late age at first full term birth is strongly associated with lobular breast cancer
Version of Record online: 10 NOV 2010
Copyright © 2010 American Cancer Society
Volume 117, Issue 9, pages 1946–1956, 1 May 2011
How to Cite
Newcomb, P. A., Trentham-Dietz, A., Hampton, J. M., Egan, K. M., Titus-Ernstoff, L., Warren Andersen, S., Greenberg, E. R. and Willett, W. C. (2011), Late age at first full term birth is strongly associated with lobular breast cancer. Cancer, 117: 1946–1956. doi: 10.1002/cncr.25728
- Issue online: 19 APR 2011
- Version of Record online: 10 NOV 2010
- Manuscript Accepted: 30 AUG 2010
- Manuscript Revised: 20 AUG 2010
- Manuscript Received: 4 JUN 2010
- lobular breast cancer;
- ductal breast cancer;
- risk factors
Late age at first full-term birth and nulliparity are known to increase breast cancer risk. The frequency of these risk factors has increased in recent decades.
The purpose of this population-based case-control study was to examine associations between parity, age at first birth (AFB), and specific histological subtypes of breast cancer. Women with breast cancer were identified from cancer registries in Wisconsin, Massachusetts, and New Hampshire. Control subjects were randomly selected from population lists. Interviews collected information on reproductive histories and other risk factors. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of ductal, lobular, and mixed ductal-lobular breast cancer diagnosis in association with AFB and nulliparity.
AFB ≥30 years was associated with a 2.4-fold increase in risk of lobular breast cancer compared with AFB <20 years (OR, 2.4; 95% CI, 1.9-2.9). The association was less pronounced for ductal breast cancer (OR, 1.3; 95% CI, 1.2-1.4). Nulliparity was associated with increased risk for all breast cancer subtypes, compared with women with AFB <20 years, but the association was stronger for lobular (OR, 1.7; 95% CI, 1.3-2.2) than for ductal (OR, 1.2; 95% CI, 1.1-1.3) subtypes (P = .004). The adverse effects of later AFB was stronger with obesity (P = .03) in lobular, but not ductal, breast cancer.
Stronger associations observed for late AFB and nulliparity suggest that these factors preferentially stimulate growth of lobular breast carcinomas. Recent temporal changes in reproductive patterns and rates of obesity may impact the histological presentation of breast cancer. Cancer 2011. © 2010 American Cancer Society.