Night shift work, chronotype and prostate cancer risk in the MCC-Spain case-control study

Area of Science:

• Occupational Health
• Cancer Epidemiology
• Chronobiology

Background:

• Night shift work is a probable human carcinogen, with existing evidence primarily on breast cancer.
• Limited data exists on the association between night shift work and other common cancers like prostate cancer.
• Chronotype, an individual's circadian preference, may influence adaptation to night work.

Purpose of the Study:

• To investigate the relationship between night shift work and prostate cancer risk.
• To explore the role of chronotype and disease severity in this association.
• To provide population-based evidence from Spain on night shift work and prostate cancer.

Main Methods:

• A population-based case-control study involving 1,095 prostate cancer cases and 1,388 controls.
• Detailed lifetime occupational history including night shift schedules (duration, frequency, type).
• Unconditional logistic regression analysis adjusting for confounders, with chronotype assessed via questionnaire.

Main Results:

• Night shift work (≥1 year) was associated with a slightly increased prostate cancer risk (OR 1.14).
• Risk increased with longer exposure (≥28 years: OR 1.37, p-trend=0.047).
• Higher risk observed for high-grade tumors (RRR 1.40), particularly with long-term exposure (≥28 years: RRR 1.63, p-trend=0.027).

Conclusions:

• Night shift work is associated with an increased risk of prostate cancer, particularly for tumors with worse prognosis.
• Longer duration of night shift work amplifies this risk.
• Chronotype influences the association, with risks observed for both evening and morning types under specific exposure conditions.