Fig. 1

Display of how to analyze familial risk of LCa using a pedigree as an example. Parents and siblings were used to define family history. Cases in the offspring generation were used to estimate risk. In a, mother was first diagnosed with cancer A (first primary cancer) at age1 and then LCa-2 at age2. In b, mother was diagnosed with LCa-1. In c, no first-degree relatives were diagnosed with any cancer. LCa, lung cancer, cancer A, any cancer other than lung cancer, LCa-1, lung cancer as a first primary malignancy, LCa-2, lung cancer as a second primary malignancy