Effects of interval between age at first pregnancy and age at diagnosis on breast cancer survival according to menopausal status: a register-based study in Korea.

Jungsun Lee,Minkyung Oh

doi:10.1186/1472-6874-14-113

Abstract

BackgroundThe influence of parity and time interval between age at first pregnancy (AFP) and age at diagnosis on breast cancer survival is not established in the same way as their influence on breast cancer risk. We aimed to investigate the association of time interval or parity with prognosis in pre- and postmenopausal women in Korea.MethodsWe conducted a retrospective study of 29,167 women with breast cancer through the Korean Breast Cancer Registry from 1993–2009. Information on reproductive factors, including breastfeeding, AFP, and parity were collected from a routine questionnaire. Conditional logistic regression was used to estimate the associations between menopausal status and overall mortality (OM) and breast-cancer-specific mortality (BCSM), adjusting for treatment and stage.ResultsHigh parity (≥5) increased the hazard ratios (HR) of BCSM (HR = 1.33, 95% confidence interval (CI): 0.83–2.11, p < 0.001) and OM (HR = 1.20, 95% CI: 0.85–1.68.73, p < 0.001) in premenopausal and postmenopausal women (BCSM, HR: 1.62, 95% CI: 0.93–2.82, p < 0.001; OM, HR = 1.58, 95% CI: 1.14–2.21, p <0.001). A longer time interval between age at breast cancer diagnosis and AFP reduced the HRs of BCSM (HR = 0.97, 95% CI: 0.96–0.98, p = 0.001) and OM (HR = 0.98, 95% CI: 0.97–0.98, p < 0.001) in premenopausal women, but had an adverse effect on the HR of OM (HR = 1.03, 95% CI: 1.02–1.03, p < 0.001) in postmenopausal women.ConclusionsHigh parity (≥5) was associated with poor breast cancer prognosis in both pre- and postmenopausal women. The time intervals between reproductive events had different effects on breast cancer outcomes depending on menopausal status.Electronic supplementary materialThe online version of this article (doi:10.1186/1472-6874-14-113) contains supplementary material, which is available to authorized users.

Highlights

The influence of parity and time interval between age at first pregnancy (AFP) and age at diagnosis on breast cancer survival is not established in the same way as their influence on breast cancer risk
AFP Compared with nulliparity, any AFP decreased the hazard ratios (HR) of breast-cancer-specific mortality (BCSM) and overall mortality (OM) in premenopausal breast cancer patients
The results of this study suggest that parity, irrespective of AFP, was associated with a more favorable prognosis in terms of BCSM and OM compared with nulliparity in premenopausal women, though both early (

Summary

Introduction

The influence of parity and time interval between age at first pregnancy (AFP) and age at diagnosis on breast cancer survival is not established in the same way as their influence on breast cancer risk. An early age at first pregnancy has been shown to be protective in terms of lifetime risk of breast cancer. This protective effect may be explained by the differentiation of breast tissues induced by a full-term pregnancy, resulting in lower susceptibility to carcinogenic influences [1]. Events considered to be protective in terms of breast cancer risk, such as early age at first pregnancy and increased parity, may have an adverse. It is possible that the tissue changes associated with pregnancy may make the breast more or less susceptible to carcinogenic factors [15], and the resulting effects may depend on the underlying genetic susceptibility to breast cancer [17]. It is possible that factors related to age at menarche, the timing of pregnancies, the prevalence of breastfeeding, and age at menopause may either initiate or inhibit specific types of breast cancers with different degrees of aggressiveness

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