Familial and second esophageal cancers: a nation-wide epidemiologic study from Sweden

A few case-control studies have been published on familial risks in esophageal cancer. Reliable data on familial risks are needed for prevention and clinical decisions. We used the nation-wide Swedish Family-Cancer Database on 10.1 million individuals and close to 6000 esophageal cancers to calculate standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for esophageal cancer in 0-66-year-old offspring by cancers in family members. Additionally, SIRs for second esophageal cancers were analyzed. The SIR for esophageal cancer was 3.91 (95% CI 1.55-7.35) when a parent presented with esophageal cancer and 4.91 (95% CI 1.77-9.62) when a parent presented with squamous cell carcinoma. The sibling risk for esophageal cancer was increased but was based on 1 pair only. The population-attributable proportion of familial esophageal cancer was 0.70%. Risks for second esophageal cancers were increased after upper aerodigestive tract, esophageal, stomach, larynx, and lung cancers. The data on second cancers suggest that environmental factors are important for esophageal cancer and probably contribute to the familial clustering. However, the high familial risk of 3.91 is unlikely without the involvement of heritable factors. The population-attributable proportion of familial esophageal cancer is small.