Circadian rhythm disrupting behaviours and cancer outcomes in breast cancer survivors: a systematic review

Kelly D’cunha, Yikyung Park, Melinda M. Protani, Marina M. Reeves

Research output: Contribution to journalReview articlepeer-review

3 Scopus citations


Purpose: Circadian rhythm disruptors (e.g., night-shift work) are risk factors for breast cancer, however studies on their association with prognosis is limited. A small but growing body of research suggests that altered sleep patterns and eating behaviours are potential mechanistic links between circadian rhythm disruptors and breast cancer. We therefore systematically summarised literature examining the influence of circadian rhythm disrupting behaviours on cancer outcomes in women with breast cancer. Methods: A systematic search of five databases from inception to January 2021 was conducted. Original research published in English, assessing the relationship between post-diagnosis sleep patters and eating behaviours, and breast cancer outcomes were considered. Risk of bias was assessed using the Newcastle–Ottawa Assessment Scale for Cohort Studies. Results: Eight studies published original evidence addressing sleep duration and/or quality (k = 7) and, eating time and frequency (k = 1). Longer sleep duration (≥ 9 h versus [referent range] 6-8 h) was consistently associated with increased risk of all outcomes of interest (HR range: 1.37–2.33). There was limited evidence to suggest that measures of better sleep quality are associated with lower risk of all-cause mortality (HR range: 0.29-0.97). Shorter nightly fasting duration (< 13 h versus ≥ 13 h) was associated with higher risk of all breast cancer outcomes (HR range: 1.21–1.36). Conclusion: Our review suggests that circadian rhythm disrupting behaviours may influence cancer outcomes in women with breast cancer. While causality remains unclear, to further understand these associations future research directions have been identified. Additional well-designed studies, examining other exposures (e.g., light exposure, temporal eating patterns), biomarkers, and patient-reported outcomes, in diverse populations (e.g., breast cancer subtype-specific, socio-demographic diversity) are warranted.

Original languageEnglish
Pages (from-to)413-421
Number of pages9
JournalBreast Cancer Research and Treatment
Issue number3
StatePublished - Apr 2023


  • Breast neoplasms
  • Circadian rhythm
  • Feeding behaviour
  • Sleep quality
  • Survival


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