Lifestyle Changes Could Prevent Half of Common Cancers

More than 50% of cancer could be prevented if people simply implemented what is already known about cancer prevention, according to a new study.

A researcher at Washington University School of Medicine (St. Louis, MO, USA) reports that that a number of interventions, largely involving lifestyle behaviors, but also involving higher-cost interventions in high-income countries, could prevent a large proportion of cancers in 15 to 20 years if widely applied. Among the measures mentioned was smoking cessation. One third of cancer in high-income countries is caused by smoking; by reducing smoking to about 11%, a 75% reduction in smoking-related cancers could be expected in 10 to 20 years.

Similarly, it is estimated that being overweight or obese causes approximately 20% of cancer today. If people could maintain a healthy body mass index (BMI) between 21 and 23 kg/m², the incidence of cancer could be reduced by approximately 50% in 2 to 20 years. Poor diet and lack of exercise are each associated with about 5% of all cancers. Improvement in the quality of food consumption could reduce cancer incidence associated with diet by 50%, and increases in physical activity could reduce cancer incidence by as much as 85% in 5 to 20 years.

Eradicating the main viruses associated with cancer worldwide by implementing widespread infant and childhood immunization programs targeting 3 viruses--Human papillomavirus (HPV) and hepatitis B and C--could lead to a 100% reduction in viral-related cancer incidence in 20 to 40 years. Other interventions could prevent a significant proportion of cancer and cancer-related mortality, starting with breast cancer. Tamoxifen and raloxifene have been shown to reduce the risk for invasive breast cancer by about 50% at 5 years. And bilateral oophorectomy in women carrying the BRCA1 or BRCA2 gene, although rare, has been associated with a 50% reduction in breast cancer risk among high-risk women.

It has also been estimated that weight loss after menopause of more than 9 kg reduces breast cancer risk by 50% in 2 to 20 years. Also, approximately 20 years of follow-up has shown that aspirin is associated with a 40% reduction in mortality from colon cancer. Similarly, screening for colorectal cancer has a similar magnitude of mortality reduction (30% to 40%). The study was presented at the Union for International Cancer Control (UICC) World Cancer Congress, held during September 2012 in Montreal (Canada).

“Thirty years ago, epidemiologists were already showing that tobacco, alcohol, and diet — which in their definition was the sum of dietary intake, lack of physical activity, and obesity — accounted for more than half of all cancer. We can't expect these changes in outcome to occur overnight, but they could bring huge benefits to society,” said study author and presenter Graham Colditz, PD, PhD.

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Washington University School of Medicine