Risk of Breast Cancer among Night Shift Working women: A Comprehensive Narrative review of Epidemiological Evidence and Occupational Health implications for Indian Women

Abstract

Background: According to the International agency for Research on Cancer (IARC) night shift work is classified as a probable human carcinogen with an impact of approximately 15~20% of the workforce across the world. The Circadian disruption arising from night shift work suppresses secretion of melatonin, dysregulation of estrogen metabolism and changes the clock gene expression that have been proposed to be linked with Breast cancer development.
Objective: To review on the existing epidemiological evidence on the association between Risk of Breast cancer and night shift working women, policy recommendations and occupational health outcomes for Indian Women
Methods: A comprehensive narrative review was conducted using Pubmed, Scopus, Google Scholar, and the WHO index, Peer-reviewed studies published between 2000 – 2026.
Key Findings: There is a significant association between long duration of night shift work and increased breast cancer risk (Relative risk ~1.086 per 5-year increment of exposure). Workers with rotating shift has higher circadian disruption and risks of developing breast cancer compared to permanent night shift work. IARC 2019 monograph classifies night shift work as a probable human carcinogen under Group 2A. Longitudinal data for India-specific studies is still limited.
Conclusion: With increasing night shift jobs in India and Breast cancer being the leading cause of neoplasm among Indian Women there is definite need for occupational policies ensuring women welfare and more clinical research on the same to be done on a larger scale with more longitudinal study.