An article published in the prestigious journal Nature shows that the development of the vast majority of cancers is strongly influenced by factors associated with lifestyle. It is therefore a good opportunity to remind people that it is possible to prevent most cancers by simply modifying our habits .
Most people perceive cancer as a bad game of chance against which nothing can be done. According to this view, cancer is always caused by factors beyond our control, whether it is heredity, aging, stress or pollution. These false beliefs go completely against what research has identified as triggers for cancer.
Heredity, for example, does not play the predominant role that we often believe. There are indeed some defective genes that can be passed on by heredity, but these inherited cancers are relatively infrequent. For example, a recent study of more than 200 identical twins shows that the vast majority of cancers, especially those which mainly affect the population Western countries (lung, colorectal, breast and prostate), are not of hereditary origin.
Significant differences from country to country ‘other
To better understand these factors, a team of American scientists rigorously analyzed several studies on the worldwide distribution of cancers as well as on some of their molecular characteristics. They first noticed that chance, heredity or even aging cannot explain the phenomenal differences that exist in the incidence of several types
of cancer in the global scale. Breast cancer is up to 20 times more common in America than in Asia, for example, while Westerners are 000 times more affected by prostate cancer than the Japanese. These differences are completely canceled out following the migration of Asians to the West, which highlights the contribution of lifestyle to the development of these cancers.
Cancer does not start overnight
In addition, analysis of the molecular composition of cancers also suggests a major contribution of extrinsic factors , related to lifestyle. Thus, the mutations found in most cancers have a molecular signature typical of exposure to carcinogenic substances (UV rays, tobacco, poor diet) and not that associated with normal aging. Most cancers also require multiple mutations to reach a mature stage (nine mutations for breast cancer, 10 for colon cancer and 11 for that of the prostate) and the statistical calculation indicates that a cancer cell cannot simply acquire by chance all these mutated genes on the scale of a human life.
Taking these factors into account, the authors estimate that a minimum of 68% of cancers are caused by lifestyle factors, a contribution that almost reaches 98% for cancers such as colon and lung, two cancers with high mortality.
Risk factors related to lifestyle
Lifestyle can influence cancer risk, regardless of genetic predisposition. Thus, the risk of developing early breast cancer (before 50 years) in women carrying defective BRCA genes has tripled in recent years (20 to 67%), an increase attributed to the increase obesity, unhealthy diet and decreased physical activity.
Regardless of heredity, non-modifiable risk factors are also influenced by lifestyle : a population analysis recently showed that women who are at higher risk of breast cancer because of certain factors beyond their control (family history, long fertility period without pregnancy, tall height) can reduce this risk by following the recommendations issued by the World Cancer Research Fund. Thus, these high-risk women who maintain a healthy weight and who avoid consuming too much alcohol have 24% lower risk of developing breast cancer, same protection as those that are not at high risk.
Simple preventive actions
The countless studies of recent years clearly show that the high incidence of the main cancers that affect our society ( lung, colon, breast, prostate) is mainly caused by the Western way of life and that we can prevent these cancers by adopting healthy lifestyle habits: no smoking, diet rich in plants, maintenance of body weight normal, adequate sleep and regular physical activity. In the end, taking care of your health by preventing cancer remains simple.
Mucci LA et al. Familial risk and heritability of cancer among twins in Nordic countries. JAMA 2016; 315: 68 – 76.
Wu S et al. Substantial contribution of extrinsic risk factors to cancer development. Nature. 2016; 529: 29 – 7.
Nkondjock A et al. Diet, lifestyle and BRCA-related breast cancer risk among French-Canadians. Breast Cancer Res Treat. 2006; 98: 285 – 285.
Nomura SJ et al. WCRF / AICR recommendation adherence and breast cancer incidence among postmenopausal women with and without non-modifiable risk factors. Int. J. Cancer.
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