Family History and the Risk of Breast and Gastric Cancer

Epidemiologists have used family history, usually of first degree relatives, as a marker for genetic risk, knowing that family history reflects the consequences of genetic susceptibilities, shared environment, and common behaviors. The role of family history on breast and gastric cancer risk has been evaluated in multiple studies. As for breast cancer, informative valid,and precise estimates of the role of family history derive from a reanalysis of individual data from 52 epidemiologicstudies including over 58,000 women with breast cancer and 100,000 controls, which estimated an approximately two fold increased risk for women with family history; the risk increased with the number of affected relatives, decreased with age and was greater the younger the relatives were when their breast cancer was diagnosed. As for gastric cancer, a meta-analysis published in 2018 and based on 36 case-control and 4 cohort studies found a significant pooled relative risk of about 2; in line with that, a subsequent analysis based on individ-ual participant data from 17 studies participating in the Stomach cancer Pooling (StoP) Project foundan 80% increased risk in subject with at least on first-degree relative affected by gastriccancer.