The effect of wartime conditions and the 1944-45 'Dutch famine' on recalled menarcheal age in participants of the DOM breast cancer screening project.

In a retrospective cohort study on 21,067 women who participated in the DOM project, a breast cancer screening programme, age at menarche was studied in relation to the 'Dutch Famine' at the end of the Second World War. Menarche showed a delay during the entire war period, disrupting a secular trend pattern in both urban and rural areas. This delay could be explained by circumstances of general dearth and food rationing. The data did not show a clear effect of famine exposure over and above effects related to the entire war period. Where age at menarche is a risk factor for breast cancer, effects due to a modest limitation of caloric intake such as accomplished by the food rationing may be more relevant as to its public health impact on cancer risk reduction than any additional effects due to outright starvation as occurred during the 'hungerwinter'.