Familial association of lung cancer with liver cancer in first-degree relatives.

Besides the smoking and occupational exposures, heritable factors have been proven to be a risk factor for lung cancer by several population-based studies, which would misestimate the risk of lung cancer. To quantify the magnitude of the high risk of lung cancer with family history, we performed a case-based study with 1373 enrolled individuals, which may be more accurate than a population-based study. Risk of lung cancer was higher in people with lung cancer family history than in the control group (OR 2.50, <0.001). Individuals with family history of liver cancer also had a higher risk of lung cancer than the control group (OR 1.78, =0.038) while there was no significant difference within the individuals with family history of colorectal cancer, esophageal cancer, nasopharyngeal cancer or breast cancer. Furthermore, the risk of lung cancer in the subjects with early-onset cancers (age <50 years) was higher than the later-onset cancers (age ≥50 years), especially in individuals with family history of liver cancer (OR 9.24 vs 1.39). Risk of lung cancer in females with family history of lung cancer or liver cancer was higher than in males. The results of this study proved that the familial aggregation of lung cancer and liver cancer manifests higher risks of lung cancer, supporting the hypothesis that lung cancer and liver cancer are attributable to common familial predisposition.