Aim: The objective of the study was to examine the impact of WWII-related caloric restriction (CR) on subsequent breast cancer (BC) risk based on individual exposure experiences and whether this effect was modified by age at exposure. Methodology: We compared 65 breast cancer patients diagnosed between 2005-2010 to 200 controls without breast cancer who were all members of various organizations for Jewish WWII survivors in Israel. All participants were Jewish women born in Europe prior to 1945 who lived at least 6 months under Nazi rule during WWII and immigrated to Israel after the war. We estimated CR using a combined index for hunger and used logistic regression models to estimate the association between CR and BC, adjusting for potential confounders. Results: Women who were severely exposed to hunger had an increased risk of BC (OR=5.0, 95% CI= 2.3-10.8) compared to women who were mildly exposed. The association between CR and BC risk was stronger for women who were exposed at a younger age (0-7 years) compared to the risk of BC in women exposed at ≥ 14 years (OR= 2.8, 95% CI=1.3-6.3). Conclusions: Severe exposure to CR is associated with a higher risk for BC decades later, and may be generalized to other cases of severe starvation during childhood that may have long-term effects on cancer in adulthood.