Lifestyle and cancer incidence and mortality risk depending on family history of cancer in two prospective cohorts.

Drake I1, Dias JA2, Teleka S3, Stocks T3, Orho-Melander M1.

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Abstract

The extent to which a favourable lifestyle may lower cancer risk in subjects with a family history of cancer is unknown. We conducted a prospective study in two Swedish cohorts, the Malmö Diet and Cancer Study (MDCS; N=25,604) and the Malmö Preventive Project (MPP; N=16,216). The association between a favourable lifestyle (based on non-smoking, normal-weight, absence of excessive drinking, regular physical activity, and healthy diet) and cancer incidence and mortality risk was assessed using Cox regression stratified by family history of cancer (all types). A favourable lifestyle was associated with a 22% (95% confidence interval (CI): 18-26%) and 40% (95% CI: 36-44%) lower risk of cancer incidence and mortality, respectively, compared to an unfavourable lifestyle. No significant effect modification by family history was observed but there was a null association between lifestyle and cancer incidence among subjects with two or more affected first-degree relatives. The observed relative risk estimates comparing an unfavourable with a favourable lifestyle corresponded to standardized 10-year cancer incidence rates of 11.2 versus 9.5% in the MDCS, and 4.4 versus 3.2% in the MPP, and a reduction in 20-year cancer mortality rate from 11.7 to 7.4% in the MDCS and 6.7 to 3.9% in the MPP. Improved adherence to cancer prevention recommendations may reduce cancer incidence and mortality risk in the general population, however, further studies are needed to assess the impact of lifestyle on cancer incidence among subjects with strong familial or polygenic risk for specific cancers. This article is protected by copyright. All rights reserved.