Low tobacco-related cancer incidence in offspring of long-lived siblings: a comparison with Danish national cancer registry data.

PURPOSE Familial clustering of longevity is well documented and includes both genetic and other familial factors, but the specific underlying mechanisms are largely unknown. We examined whether low incidence of specific cancers is a mechanism for familial clustering of longevity. METHODS The study population of individuals from longevity-enriched families consisted of 3267 offspring from 610 Danish long-lived families defined by two siblings attaining an age of 90 years or more. The offspring of the long-lived siblings were followed from 1968 to 2009. Using high-quality registry data, observed numbers of cancers were compared with expected numbers based on gender-, calendar period-, and age-specific incidence rates in the general population. RESULTS During the 41-year-follow-up period, a total of 423 cancers occurred in 397 individuals. The standardized incidence ratios (95% confidence interval) for offspring of long-lived individuals were 0.78 (0.70-0.86) for overall cancer; 0.66 (0.56-0.77) for tobacco-related cancer; 0.34 (0.22-0.51) for lung cancer; 0.88 (0.71-1.10) for breast cancer; 0.91 (0.62-1.34) for colon cancer. CONCLUSIONS The low incidence of tobacco-related cancers in long-lived families compared with non-tobacco-related cancers suggests that health behavior plays a central role in lower early cancer incidence in offspring of long-lived siblings in Denmark.