The believed causes of breast cancer are myriad and well-documented – family history; age; time and type of menopause (i.e. natural or induced by surgery where ovaries are removed); whether or not the woman has had children; over-indulgence of alcohol; smoking; HRT; a compromised immune system etc. To this long list has just been added the height of the person, the age at which a woman began menstruating and – perhaps most crucially – obesity.
Breast cancer is not just one cancer. Information on the CancerHelp website gives 16 different types – 17 if you include breast cancer in men as a type on its own. This latter form of the disease has its own causes, among which are environmental influences, lifestyle and genetic factors. The majority of breast cancers found in men are oestrogen receptive.
Oxford University’s study concludes that “the chances of developing breast cancer rise by 16 per cent for every 4 inches in height”. Apparently, this is due to the high levels of growth hormones in taller women, who are 28 per cent more likely to develop oestrogen-dependent breast cancer. I wonder – does this apply to breast cancer in men too?
In May, the latest batch of results from the Breakthrough Breast Cancer’s “Generations” study (which is looking at 110,000 women over 40 years to pin-point the causes of breast cancer) were published. The conclusion (in association with the Institute of Cancer Research) – published in the journal of Paediatric and Perinatal Epidemiology – is that girls from poorer backgrounds are beginning to menstruate almost a year earlier than girls from more affluent families. The earlier that a girl begins to menstruate, the more chance she has of developing breast cancer because her body will be exposed to oestrogen for a longer time. One of the reasons given for the drop in the age of menarche is that girls from less affluent backgrounds are more likely to be carrying too much weight and not exercising on a regular basis. It has been suggested that, by encouraging a child to take regular exercise, the onset of menstruation may be delayed – and, of course, the extra pounds shed.
Figures show that one in five women in the UK is now so overweight that their health is at risk – obesity has more influence on hormone levels than does alcohol or smoking. Were all these women overweight as children? Fat tissue secretes oestrogen and research shows that obese women have 50 per cent higher levels of oestrogen in their bodies – hence the greater chance of developing certain types of breast cancer. Does this mean that post-menopausal women who are also obese have little chance of not developing the disease?