[Interaction between family history and smoking in lung cancer]

Case-control analysis of the data from Aichi Cancer Registry revealed that when smoking and family history of lung cancer were combined, relative risk of this cancer increased in an additive manner to the higher level than that for each single factor. This risk increase was larger for squamous cell carcinoma than for adenocarcinoma (relative risk; 4.02 vs 2.20). Other data from three case-control studies were discussed, and a new approach of familial case-control study of cancer was proposed. Finally importance of cancer prevention and detection for families at high risk of cancer was stressed.