A 5-year counseling intervention advising adult men on healthy lifestyles and diet reduced the risk of cancers related to obesity and smoking in the first 25 years, but did not reduce the long-term risk of cancers overall, according to a study published in the Journal of Internal Medicine

A study initiated in 1972 to 1973 showed that men at high risk of coronary heart disease (CHD) who were counseled to stop smoking and improve diet habits decreased their long-term risk of developing cardiovascular disease and associated mortality. As many modifiable risk factors are shared between cardiovascular disease and cancer, researchers broadened the scope to assess the impact this intervention may have had on cancer risk. 

In the Oslo diet and antismoking study, researchers randomly assigned 1218 men at high risk of CHD to a 5-year intervention for lifestyle changes to decrease cholesterol, weight, and smoking, or a control group. To assess the impact of this intervention on cancer outcomes, investigators merged the data from the Oslo study with data from the Cancer Registry of Norway and the Norwegian Cause of Death Registry from 1972-1973 to the end of 2015. 

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After 43 years, results showed that the intervention did not reduce the risk of cancer. In the first 25 years, however, the almost 90% of men who were overweight/obese and/or smokers had a reduced risk of developing cancers associated with the risk factors addressed by the intervention, such as lung, gastrointestinal, and urinary cancers. 

There were no effects observed past 25 years on the risk of cancer or on mortality. 

Reference

Botteri E, de Lange T, Tonstad S, Berstad P. Exploring the effect of a lifestyle intervention on cancer risk: 43-year follow-up of the randomized Oslo diet and antismoking study[published online May 22, 2018]. J Intern Med.doi: 10.111/joim.12765