The
International Agency for Research on Cancer has hold that
overweight and obesity responsible for 9% of postmenopausal
breast cancer, 11% of colon cancer, 25% of renal cancer, 37% of oesophageal cancer and 39% of endometrial cancer. Obesity was associated with higher risk of dying from 14
cancers (oesophagus, colon and rectum, liver, gallbladder, pancreas, kidney, non-Hodgkin lymphoma, multiple myeloma, stomach, prostate, breast, uterus, cervix and ovary). According to estimates, 14% of all cancer deaths in men and 20% in women are caused by overweight and obesity.
Reasons for the increased cancer risk (breast, endometrium and colon) may be alterations of the levels of sex hormones (e.g. oestrogen, progesterone and androgens), insulin and IGF-1. The concentration of sex-hormone binding globulin, the major carrier protein for some sex
hormones in the plasma, may also be influence the obesity-correlated risk for these cancers.
Stress & Cancer
An excess of
stress may lead to suppressed immune functions, and if chronic, appears to be even more harmful. Social and psychosocial disadvantages lead to increased stress and are, thus, associated with manifestation and progression of malignant diseases. Hence, it is not astonishing that most
cancers (e.g. cervix, ovarian and lung cancer, malignancies of the upper respiratory and digestive organs) are observed more frequently in societies of lower rank, as confirmed by retrospective and limited prospective studies.
Socio-economic stress
Obesity is often stigmatised in our society leading to social isolation, occupational and educational discrimination and widespread expression of negative attitudes. Lower
socio-economic position is apparently associated with obesity. The consequences of social factors for the development of obesity are often neglected. A growing number of studies confirm the correlation between social stress,
depression and
obesity. Especially in children, obesity is tightly associated with depression.
Gene x environment interactions
People with certain genetic backgrounds are particularly endangered for weight gain and obesity-related diseases may be also, to a certain extent genetical, especially when aggravated by an unsound lifestyle.
An alarming example are the Pima Indians of Arizona, USA. Lifestyle changes have resulted in a dramatic increase of obesity and diabetes within this population during the past 50 years. By now, the Pimas living in Arizona consume a high-fat diet (50% of energy as fat) provided by government surplus commodities instead of their traditional low-fat diet (15% of energy as fat) and are, hence, much less motile than at that time they used to be farmers. In contrast, Pima Indians who live in the Sierra Madre mountains of Northern Mexico and consequently have been isolated from Western influences, eat a traditional Pima diet and are still physically active as farmers and sawmill workers. The Pimas of Mexico show a much lower incidence of obesity and diabetes than their genetic kindreds in Arizona.
References:
Geyer S: The role of social and psychosocial factors in the development and course of cancer. Wien Klin Wochenschr. 2000 Dec 7;112(23):986-94
Stein et al.: The epidemic of obesity. The Journal of Clinical Endocrinology and Metabolism, Vol 89(6):2522-2525, 2004:
For further reading visit:
Go VLW. et al. Diet and Cancer Prevention: Evidence-based Medicine to Genomic Medicine. J. Nutr. 134: 3513S–3516S, 2004.Tsigos C. and Chrousos G.P. Stress, obesity, and the Metabolic Syndrome (Soul and Metabolism). Ann. N.Y. Acad. Sci. 1083:xi-xiii (2006)Tamashiro KL et al. Chronic social stress in a changing dietary environment. Physiol Behav. 2006 Nov 30;89(4):536-42.
