The idea that a low-calorie diet may reduce the risk of breast cancer has helped to sell several popular cancer-prevention diet books. But a short and sudden bout of starvation may do just the opposite, according to a new study that finds higher breast cancer rates in Dutch women who lived through a brief famine at the end of World War II.
As Allied forces tried to bring the war to a rapid conclusion by advancing on the Rhine bridge in Arnhem, The Netherlands, in the fall of 1944, German authorities imposed a food embargo. For 6 months, the Dutch starved. Adult caloric intake plummeted from 1500 to 700 kilocalories per day. Food abruptly became abundant again when The Netherlands was liberated on 5 May 1945.
To determine whether famine had an effect on the incidence of breast cancer, epidemiologist Sjoerd Elias and colleagues at the Julius Center for Health Sciences and Primary Care in Utrecht analyzed data from a breast cancer study that began in 1974. Between 1983 and 1986, as part of the screening protocol for the study, a group of 15,396 participants who lived through the famine responded to a detailed questionnaire. From their answers, Elias's group calculated a "famine score" that estimated the degree of malnutrition of each participant. Then they randomly selected 2352 women and referenced their health records against various cancer registries.
Women who reported being hit hardest by the famine had a significantly elevated risk of breast cancer, 1.5 times higher than those who had had the most to eat, the group reports in the 7 April issue of the Journal of the National Cancer Institute. The risk was even more pronounced, two times higher, for those aged 2 to 9 at the time of the famine. The researchers suspect that temporary malnutrition followed by plentiful food at a young age may have had a lasting effect on the balance of hormones--such as insulinlike growth factor I and sex steroids--that have been linked to breast cancer.
"The rather surprising results ... [also] remind scientists to keep an open mind on the direction of any effects of starvation on cancer risk," says cancer epidemiologist Tim Key of the University of Oxford, U.K. He adds that the study is an "important contribution" because it's the first to relate breast cancer risk to women's self-reported estimates of starvation intensity, which are more precise than demographics alone, but he cautions that the findings still need to be confirmed.
Background on the "Hunger Winter" of 1944-1945