Effect of time of day of recreational and household physical activity on prostate and breast cancer risk (MCC-Spain study).

Jakob Weitzer,Marcela Guevara,Rafael Marcos‐Gragera,Gemma Castaño‐Vinyals,Virginia Lope,Juan Alguacil,Delphine Casabonne,Beatriz Pérez‐Gómez,Vicente Martín,Pilar Amiano,Kyriaki Papantoniou,Nieves Ascunce,Javier Llorca,Marina Pollán,Inés Gómez‐Acebo,Manolis Kogevinas,Leire Gil,Ana Molina‐Barceló ,Esther Gràcia-Lavedán ,José Juan Jiménez-Moleón ,Vı́ctor Moreno ,Núria Aragonés ,Claudia Suárez-Calleja

doi:10.1002/ijc.33310

Abstract

Experimental evidence indicates that exercise performed at different times of the day may affect circadian rhythms and circadian disruption has been linked to breast and prostate cancer. We examined in a population‐based case‐control study (MCC‐Spain) if the time‐of‐day when physical activity is done affects prostate and breast cancer risk. Lifetime recreational and household physical activity was assessed by in‐person interviews. Information on time‐of‐day of activity (assessed approximately 3 years after the assessment of lifetime physical activity and confounders) was available for 781 breast cancer cases, 865 population female controls, 504 prostate cases and 645 population male controls from 10 Spanish regions, 2008‐2013. We estimated odds ratios (ORs) and 95% confidence intervals (95% CI) for different activity timings compared to inactive subjects using unconditional logistic regression adjusting for confounders. Early morning (8‐10 am) activity was associated with a protective effect compared to no physical activity for both breast (OR = 0.74, 95% CI = 0.48‐1.15) and prostate cancer (OR = 0.73, 95% CI = 0.44‐1.20); meta‐OR for the two cancers combined 0.74 (95%CI = 0.53‐1.02). There was no effect observed for breast or prostate cancer for late morning to afternoon activity while a protective effect was also observed for evening activity only for prostate cancer (OR = 0.75, 95% CI = 0.45‐1.24). Protective effects of early morning activity were more pronounced for intermediate/evening chronotypes for both cancers. This is the first population‐based investigation identifying a differential effect of timing of physical activity on cancer risk with more pronounced effects for morning hour activity. Our results, if confirmed, may improve current physical activity recommendations for cancer prevention.

Highlights

Physical activity is an established protective factor for overall cancer risk[1,2,3] and for specific major cancers such as colorectal and breast cancer
When setting the activity threshold to >0.5 metabolic equivalents (METs) * h/week risk estimates were lower across all timing categories (Supporting Information Table 5), being more active was associated with lower cancer risk
We observed that the overall protective effect of recreational and household physical activity for cancer may vary depending on the time of the day of the activity

Summary

Introduction

Physical activity is an established protective factor for overall cancer risk[1,2,3] and for specific major cancers such as colorectal and breast cancer. Circadian disruption results when the endogenous circadian rhythms are not in synchrony with environmental and social cues such as light exposure, work hours, diet and activity patterns and so forth. Exposure to artificial light at night, night shift work and mistimed diet may interfere with the normal nocturnal melatonin production and disrupt the circadian clock with numerous other biological consequences.[6,7,8] Both breast and prostate cancer have been associated with different aspects of circadian disruption. A diurnal pattern of diet has been associated with lower prostate and breast cancer risk,[11,12] while exposure to artificial light at night and exposure to blue light spectrum light has been associated with higher breast and prostate cancer risk.[13,14]

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