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BioMed Research International
Volume 2017, Article ID 4845059, 11 pages
https://doi.org/10.1155/2017/4845059
Review Article

Long-Term Sleep Duration as a Risk Factor for Breast Cancer: Evidence from a Systematic Review and Dose-Response Meta-Analysis

1Department of Surgical Oncology and General Surgery, The First Hospital of China Medical University, No. 155 Nanjing North Street, Heping District, Shenyang, Liaoning Province 110001, China
2Department of Clinical Epidemiology and Evidence-Based Medicine, The First Hospital of China Medical University, No. 155 Nanjing North Street, Heping District, Shenyang, Liaoning Province 110001, China
3Department of Gynaecology, The First Hospital of China Medical University, No. 155 Nanjing North Street, Heping District, Shenyang, Liaoning Province 110001, China
4Department of Breast Oncology and General Surgery, The First Hospital of China Medical University, No. 155 Nanjing North Street, Heping District, Shenyang, Liaoning Province 110001, China

Correspondence should be addressed to Yingying Xu; moc.oohay@ratsumcevol and Huimian Xu; moc.621@naimiuhux

Received 3 June 2017; Revised 11 August 2017; Accepted 23 August 2017; Published 10 October 2017

Academic Editor: Giske Ursin

Copyright © 2017 Chunyang Lu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Sleep patterns have been associated with the development of cancers, although the association between sleep duration and breast cancer remains controversial. The purpose of our study was to explore the relationship between sleep duration and breast cancer risk. The PubMed and Web of Science databases were searched, and restricted cubic splines were used to explore the dose-response relationship. Data from 415,865 participants were derived from 10 studies. A J-shaped nonlinear trend was found between sleep duration and breast cancer incidence ( = 0.012); compared with the reference hours (6 h or 7 h), with increasing sleep hours, the risk of breast cancer increased ( = 0.028). Moreover, a nonlinear relationship was found between sleep duration and estrogen receptor-positive breast cancer ( = 0.013); the risk of estrogen receptor-positive breast cancer increased with increasing sleep hours compared to the reference hours ( = 0.024). However, no nonlinear relationship was found between sleep duration and estrogen receptor-negative breast cancer; the risk of estrogen receptor-negative breast cancer was 1.035 for every additional sleep hour. Compared to women with the reference number of sleep hours, women with a longer sleep duration might have a significantly increased risk of breast cancer, especially estrogen receptor-positive breast cancer.