There’s something about breast cancer research which I find a little disturbing. Obviously research is essential, but I am struck by the overwhelming emphasis on finding a cure, rather than reporting causes.
When experts do focus on causes, they tend to isolate alcohol, obesity and genetics. There are other causes too, but rarely do we hear about a significant, very much overlooked factor, and that is insulin. This is a well researched area, and the results are consistent.
The hormone insulin is a significant causative factor in the development of breast cancer. To quote the literature, “ A fairly large body of evidence has demonstrated that insulin is a tumour-promoting agent, specially for breast cancer.” Insulin is released in response to elevated sugar – glucose – in the blood. Food with a high glycaemic index – sugars and refined carbohydrates – have been found to significantly increase the risk of breast cancer. This would explain why women with type 2 diabetes are known to be at greater risk of developing the disease.
Those with insulin resistance are also at risk. This is a condition, a step away from diabetes, where there are high levels of this hormone circulating in the blood and to which the body has become desensitised. It stops responding to the insulin, so levels remain high. Insulin is stimulated by carbohydrates – the more carbs you eat, and the higher the glycaemic index of those carbs, the more insulin you produce. The glycaemic index is the speed at which the sugar in a food enters the blood.
Virtually all junk and snack food is carbohydrate-based with a high glycaemic index. By telling women they drink too much and eat too much, the blame is placed squarely on the women themselves without considering the role of the food industry. Focussing on genetics also detracts from the real issues. It was recently widely reported in the media that scientists may soon be able to develop a blood test to identify women most at risk from breast cancer. This may be useful, but only about 3 per cent of all breast cancer cases are due to an inherited breast cancer gene. Furthermore, the focus on genetics ignores the fact that the number of cases of breast cancer in the UK (and elsewhere) is snowballing. Between 1979 and 2008 the incidence rate of breast cancer in Britain increased by 65%. It is projected that from 2005 until 2024 the number of new cases each year will rise by 55,700 – more than double the number of cases registered in 1979. The lifetime risk of developing breast cancer is now 1 in 8. Genetics have nothing to do with this dramatic increase in cases.
Yes, alcohol intake and obesity are both significantly associated with increased risk of developing the disease. There is much women can, and should do, to minimise their risk. But let’s not let ignore the role of the food industry which currently enjoys a level of advertising and marketing freedom once enjoyed by the tobacco industry.
Of course we should continue to look for a cure. But let’s also put much more emphasis on publicising all the well-established causes, not just the ones which feed a culture of blame.
Cancer Research UK (for statistics) www.cancerresearchuk.org
Formica, V., Tesauro, M., Cardillo, C. & Roselli, M. (2012) Insulinemia and the risk of breast cancer and its relapse. Diabetes, Obesity and Metabolism,DOI: 10.1111/j.1463-1326.2012.01614.x
Dong, J-I & Qin, L-Q (2011) Dietary glycemic index, glycemic load, and risk of breast cancer: meta-analysis of prospective cohort studies. Breast Cancer Research and Treatment, 126(2):287-294.
Gallagher, E.J. & LeRoith, D. ( ) The proliferating role of insulin and insulin-like growth factors in cancer. Trends in Endocrinology & Metabolism, 21(10):610-618.