Diet in adolescence and the risk of breast cancer: results of the Netherlands Cohort Study

Objectives: In The Netherlands, part of the population experienced food res triction and severe famine during World War II. The purpose of this study w as to study the effects of severe undernutrition during adolescence on the risk of breast cancer later in life. Methods: We examined the hypothesis in the Netherlands Cohort Study on diet and cancer (NLCS), among 62,573 women aged 55-69 years. Baseline informati on on diet and other risk factors was collected with a questionnaire in 198 6. Information was collected on residence in the Hunger winter (1944-1945) and War years (1940-1944) and fathers' employment status in 1932-1940 as in dicators of exposure. After 6.3 years of follow-up, 1009 incident breast ca ses were available for analysis. Results: In multivariate case-cohort analysis, residents of the western par t of the country in 1944-1945 had an increased breast cancer risk (western city RR=1.1, 95% CI: 0.9-1.4, western rural area RR = 1.5, 95% CI: 1.1-1.9) . For the War years (1940-1944) we found no association between breast canc er risk and urban vs. rural residence. Women whose fathers were unemployed during the Depression years (1932-1940) had a non-significant decrease in b reast cancer risk (RR = 0.9, 95% CI: 0.7-1.2). Exposure to energy restricti on during the adolescent growth spurt or during the period between menarche and birth of the first child did not change the RRs substantially. Conclusions: We found no clear evidence in this study for the hypothesis th at energy restriction in adolescence leads to a decreased breast cancer ris k.