1 ISGlobal, Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain
2 IMIM (Hospital del Mar Medical Research Institute), Barcelona, Spain
3 Universitat Pompeu Fabra (UPF), Barcelona, Spain
4 CIBER Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
5 Instituto de Investigación Sanitaria de Palma (IdISPa), Hospital Universitari Son Espases, Palma de Mallorca, Spain
6 Environmental and Cancer Epidemiology Unit, National Center of Epidemiology, Instituto de Salud Carlos III, Madrid, Spain
7 IDIBELL-Catalan Institute of Oncology, L’Hospitalet de Llobregat, Spain
8 Department of Clinical Sciences, Faculty of Medicine, University of Barcelona, Barcelona, Spain
9 Universidad de Cantabria - IDIVAL, Santander, Spain
10 Subdirección de Salud Pública de Gipuzkoa, Donostia, Spain
11 Instituto de Salud Pública de Navarra, Pamplona, Navarra
12 Universidad de León, León, Spain
13 Centro de Investigación en Salud y Medio Ambiente (CYSMA), Universidad de Huelva, Huelva, Spain
14 Instituto Universitario de Oncología, Universidad de Oviedo, Oviedo, Asturias, Spain
15 Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunitat Valenciana FISABIO – Salud Pública, Valencia, Spain
16 Instituto de Investigación Biosanitaria de Granada (ibs.GRANADA), Hospitales Universitarios de Granada/Universidad de Granada, Granada, Spain
17 Epidemiology Unit and Girona Cancer Registry, Oncology Coordination Plan, Department of Health, Autonomous Government of Catalonia, Catalan Institute of Oncology, Girona Biomedical Research Institute (IdiBGi), Girona, Spain
Purpose: In 2007 the IARC classified shift work involving circadian disruption as probably carcinogenic to humans. Perturbed circadian system in modern life involves erratic eating patterns. Mistimed eating patterns are associated with several health endpoints in experimental studies. Studies on nutrition and cancer focus on “what” and “how much” we eat rather than on “when” we eat. We assessed whether timing of eating patterns is associated with breast and prostate cancer risk.
Methods. We conducted a population-based case control study on multiple cancers in several regions in Spain. After excluding subjects who had ever worked night shift and those with incomplete information on circadian patterns, we examined data from 569 confirmed cases of prostate cancer and 795 population controls, and 1021 confirmed cases of breast cancer and 1160 population controls.
Results. Risk for both prostate and breast cancer decreased with increasing time between supper (main evening meal) and sleeping. Compared to subjects sleeping immediately after supper, those sleeping 2 hours after supper had an adjusted OR for prostate cancer of 0.73 (95%CI 0.54-0.98) with a statistically significant dose-response with time elapsed. The corresponding OR for breast cancer was 0.80 (0.62-1.01). Risk stratification by diurnal preference (an attribute reflecting personal preference for activities in the morning or evening), indicated a stronger protection for early morning types. The protection of prolonged time between supper and sleeping was strongest among subjects adhering to the WCRF/AICR recommendations (score above 4).
Conclusions. This is the first study in humans showing that timing of eating patterns is associated with cancer risk. Misclassification of exposure is inevitable when evaluating timings retrospectively and this may have diluted observed effects. However the hypothesis we tested is supported by experimental evidence and stresses the importance of evaluating circadian disruption in studies on diet and cancer.
Funding: Instituto Salud CarlosIII PI11/1889.