Dataset Information

Sleep duration and breast cancer incidence: results from the Million Women Study and meta-analysis of published prospective studies.

ABSTRACT:

Study objectives

To investigate the association between sleep duration and breast cancer incidence, we examined the association in a large UK prospective study and conducted a meta-analysis of prospective studies.

Methods

In the Million Women Study, usual sleep duration over a 24-h period was collected in 2001 for 713,150 participants without prior cancer, heart problems, stroke, or diabetes (mean age = 60 years). Follow-up for breast cancer was by record linkage to national cancer registry data for 14.3 years on average from the 3-year resurvey. Cox regression models yielded multivariable-adjusted breast cancer relative risks (RR) and 95% confidence intervals (CIs) for sleep duration categories. Published prospective studies of sleep duration and breast cancer risk were included in a meta-analysis, which estimated the inverse-variance weighted average of study-specific log RRs for short and for long versus average duration sleep.

Results

After excluding the first 5 years to minimize reverse causation bias in the Million Women Study, 24,476 women developed breast cancer. Compared with 7-8 h of sleep, the RRs for <6, 6, 9, and >9 h of sleep were 1.01 (95% CI, 0.95-1.07), 0.99 (0.96-1.03), 1.01 (0.96-1.06), and 1.03 (0.95-1.12), respectively. In a meta-analysis of 14 prospective studies plus the Million Women Study, including 65,410 breast cancer cases, neither short (RR < 7 h = 0.99 [0.98-1.01]) nor long (RR > 8 h = 1.01 [0.98-1.04]) versus average duration sleep was associated with breast cancer risk.

Conclusions

The totality of the prospective evidence does not support an association between sleep duration and breast cancer risk.

SUBMITTER: Wong ATY

PROVIDER: S-EPMC7879408 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Sleep duration and breast cancer incidence: results from the Million Women Study and meta-analysis of published prospective studies.

Wong Angel T Y ATY Heath Alicia K AK Tong Tammy Y N TYN Reeves Gillian K GK Floud Sarah S Beral Valerie V Travis Ruth C RC

Sleep 20210201 2

<h4>Study objectives</h4>To investigate the association between sleep duration and breast cancer incidence, we examined the association in a large UK prospective study and conducted a meta-analysis of prospective studies.<h4>Methods</h4>In the Million Women Study, usual sleep duration over a 24-h period was collected in 2001 for 713,150 participants without prior cancer, heart problems, stroke, or diabetes (mean age = 60 years). Follow-up for breast cancer was by record linkage to national cance ...[more]

PMID: 32886784

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Project description:It has been proposed that night shift work could increase breast cancer incidence. A 2007 World Health Organization review concluded, mainly from animal evidence, that shift work involving circadian disruption is probably carcinogenic to humans. We therefore aimed to generate prospective epidemiological evidence on night shift work and breast cancer incidence.Overall, 522 246 Million Women Study, 22 559 EPIC-Oxford, and 251 045 UK Biobank participants answered questions on shift work and were followed for incident cancer. Cox regression yielded multivariable-adjusted breast cancer incidence rate ratios (RRs) and 95% confidence intervals (CIs) for night shift work vs no night shift work, and likelihood ratio tests for interaction were used to assess heterogeneity. Our meta-analyses combined these and relative risks from the seven previously published prospective studies (1.4 million women in total), using inverse-variance weighted averages of the study-specific log RRs.In the Million Women Study, EPIC-Oxford, and UK Biobank, respectively, 673, 28, and 67 women who reported night shift work developed breast cancer, and the RRs for any vs no night shift work were 1.00 (95% CI?=?0.92 to 1.08), 1.07 (95% CI?=?0.71 to 1.62), and 0.78 (95% CI?=?0.61 to 1.00). In the Million Women Study, the RR for 20 or more years of night shift work was 1.00 (95% CI?=?0.81 to 1.23), with no statistically significant heterogeneity by sleep patterns or breast cancer risk factors. Our meta-analysis of all 10 prospective studies included 4660 breast cancers in women reporting night shift work; compared with other women, the combined relative risks were 0.99 (95% CI?=?0.95 to 1.03) for any night shift work, 1.01 (95% CI?=?0.93 to 1.10) for 20 or more years of night shift work, and 1.00 (95% CI?=?0.87 to 1.14) for 30 or more years.The totality of the prospective evidence shows that night shift work, including long-term shift work, has little or no effect on breast cancer incidence.

Project description:BackgroundEpidemiological studies have shown that taller people are at increased risk of cancer, but it is unclear if height-associated risks vary by cancer site, or by other factors such as smoking and socioeconomic status. Our aim was to investigate these associations in a large UK prospective cohort with sufficient information on incident cancer to allow direct comparison of height-associated risk across cancer sites and in relation to major potential confounding and modifying factors.MethodsInformation on height and other factors relevant for cancer was obtained in 1996-2001 for middle-aged women without previous cancer who were followed up for cancer incidence. We used Cox regression models to calculate adjusted relative risks (RRs) per 10 cm increase in measured height for total incident cancer and for 17 specific cancer sites, taking attained age as the underlying time variable. We also did a meta-analysis of published results from prospective studies of total cancer risk in relation to height.Findings1 297 124 women included in our analysis were followed up for a total of 11·7 million person-years (median 9·4 years per woman, IQR 8·4-10·2), during which time 97 376 incident cancers occurred. The RR for total cancer was of 1·16 (95% CI 1·14-1·17; p<0·0001) for every 10 cm increase in height. Risk increased for 15 of the 17 cancer sites we assessed, and was statistically significant for ten sites: colon (RR per 10 cm increase in height 1·25, 95% CI 1·19-1·30), rectum (1·14, 1·07-1·22), malignant melanoma (1·32, 1·24-1·40), breast (1·17, 1·15-1·19), endometrium (1·19, 1·13-1·24), ovary (1·17, 1·11-1·23), kidney (1·29, 1·19-1·41), CNS (1·20, 1·12-1·29), non-Hodgkin lymphoma (1·21, 1·14-1·29), and leukaemia (1·26, 1·15-1·38). The increase in total cancer RR per 10 cm increase in height did not vary significantly by socioeconomic status or by ten other personal characteristics we assessed, but was significantly lower in current than in never smokers (p<0·0001). In current smokers, smoking-related cancers were not as strongly related to height as were other cancers (RR per 10 cm increase in height 1·05, 95% CI 1·01-1·09, and 1·17, 1·13-1·22, respectively; p=0·0004). In a meta-analysis of our study and ten other prospective studies, height-associated RRs for total cancer showed little variation across Europe, North America, Australasia, and Asia.InterpretationCancer incidence increases with increasing adult height for most cancer sites. The relation between height and total cancer RR is similar in different populations.FundingCancer Research UK and the UK Medical Research Council.

Dataset Information

Sleep duration and breast cancer incidence: results from the Million Women Study and meta-analysis of published prospective studies.

Study objectives

Methods

Results

Conclusions

Publications

Sleep duration and breast cancer incidence: results from the Million Women Study and meta-analysis of published prospective studies.

Similar Datasets

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