Diet and cancer

Many factors, genetic, hormonal and environmental (tobacco, solar radiation, occupational exposure, etc.) can contribute to the development of cancer. In particular, 25% to 30% of cancers are attributable to individual behaviors such as smoking and consumption. alcohol (InVS).
About a third of cancers could be prevented by people by changing diet, increasing levels of physical activity and maintaining optimal weight (WCRF / AICR).

November 2007 was marked by the publication of the second edition of a benchmark scientific report, the result of the analysis of available scientific studies on the links between certain lifestyle habits and the risk of different types of cancer: the Food report, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective.

This expert report involved more than 200 scientists around the world and was overseen by a panel of 21 world-renowned scientists in the field of nutrition and cancer. It is published jointly by the World Cancer Research Fund (WCRF) and the American Institute for Cancer Research (AICR). This document, which took 5 years of work, systematically reviews more than 7,000 scientific studies on the link between diet, body composition, physical activity and cancers of different locations.

The relationships between nutrition and cancer risk have been studied: certain factors such as physical activity, fruit and vegetable consumption, and breastfeeding can reduce the risk of cancer. Other factors, on the other hand, can increase their risk of occurrence: such as overweight and obesity, consumption of alcoholic beverages and excessive consumption of red meats and cold meats or salt.

It is on the basis of this report that recommendations were issued in France. They are included in the brochure “Nutrition & cancer prevention: from scientific knowledge to recommendations” (INCa, NACRe network, 2009). Find on the website of the National Food Cancer Research network (NACRe) a presentation of these recommendations for the primary prevention of cancers for the French population, and of the approach which has made it possible to achieve them based on scientific knowledge.

Nutritional risk factors commonly associated with breast cancer
Weight gain (Lahmann, 2005), overweight or obesity (Calle, 2003; WCRF / AICR, 2007), lack of physical activity (Friedenreich, 2008), and alcohol consumption (INCa, 2009) ) are nutritional factors generally associated with the risk of breast cancer (mainly in the postmenopausal phase for overweight and obesity).

In a cohort study conducted between 1981 and 1999 at the Institut Curie in Paris, among 14,000 breast cancer patients (average age 54), more than 22% were overweight and 8% were obese (Majed, 2008 ); during this period, the prevalence of obesity increased dramatically, from 4% in 1981 to 11% in 1999. Five years later, in a cohort of 272 patients (mean age 52 years) followed at the Center Léon Bérard in Lyon for non-metastatic breast cancer (2004-2006), 26% were overweight and 15% were obese (Trédan, 2010).

Obesity and being overweight at the time of breast cancer diagnosis place an increased risk of relapse and excess mortality. Recommendations for breast cancer survivors in North America have indicated, for nearly a decade, the need to refer overweight or obese women to proven weight loss or stabilization programs.

In particular, reduced physical activity is one of the probable factors in weight gain after breast cancer (Demark-Wahnefried, 1997; Irwin, 2003; Harvie, 2004). Several large cohort studies of women with breast cancer have shown a 45% reduction in mortality associated with increased physical activity (Holmes, 2005; Pierce, 2007; Holick, 2008; Irwin, 2008; Friedenreich, 2009).

A diet rich in fruits and vegetables combined with regular physical activity seems to offer the best protection after breast cancer (Pierce, 2007).
The patients cured or in remission of their cancer seem however little to follow the main recommendations: among the 2,800 breast cancer survivors of the SCS-II study of the American Cancer Society questioned at 2 years, 5 years or 10 years of the diagnosis, only 37% followed the recommendations for physical activity and 18% those to consume five servings of fruits and vegetables per