October is breast cancer awareness month and it is therefore appropriate that we look into any claims of possible connections between dietary factors and this cancer. Breast (and prostate) cancer are hormonally driven and typical examples of cancer whose initiation and evolution depends on an interplay between hereditary and dietary/lifestyle factors.
Cancer in the young very often has a strong genetic basis, but cancer after middle-age (far more common) has, as a rule, a more potent dietary/lifestyle input. Breast (and prostate) cancer is far more common in Western countries than in Asia, particularly in Korea and Japan.
Although racial genetic differences might account for this, medical statistics in the US noted decades ago that within one to two generations, Japanese immigrants acquire similar breast (and prostate) cancer rates to those of other Americans. Therefore, dietary and lifestyle factors must be the predominant promoters in these cancers.
Breast tissue is under the influence of two main hormones, oestrogen and progesterone. It is theorised that too much oestrogen encourages breast cancer. Interestingly, soya beans constitute a large part of the staple diet of many Asian countries, and legumes (beans and lentils) contain very weak plant oestrogen which competes with the far stronger human oestrogen, thus dampening the effect of human oestrogen on breast tissues in women who consume significant amounts of legumes.
With modern treatment, complete cure from breast cancer is achieved in about 50 per cent of cases
Postmenopausal hormone replacement therapy (HRT) became popular in the US soon after the war. US medical statistics initially showed increased longevity in women on HRT. More recently doubts crept in about the safety of HRT due to claimed very small increases in cardiovascular disease and breast cancer. Some authors put this down to the fact that the oestrogen and progesterone used in pharmaceutical HRT preparations were not bio-identical to the human hormones and therefore chemically alien to the body. Oestrogen and progesterone which are bio-identical to the natural human hormones are available (usually in cream form, not tablets) and are claimed to carry no heart disease, stroke or breast cancer increased risk.
Obesity is statistically associated with increased risk of a number of cancers, including breast. Obesity is associated with increased blood oestrogen, insulin and ‘insulin-like growth factor-1’ (IGF-1), and all three may promote cancer including within the breast.
Furthermore, there is now increasing support for the view that obesity is particularly associated with excessive consumption of high glycaemic refined carbohydrates (sugars, refined flour foods, white rice and potato). These carbohydrates cause high blood insulin and IGF-1. Type 2 diabetics tend to have high blood insulin and IGF-1 for several years and do in fact have increased risk of cancers. Diabetic women have twice the risk of breast cancer compared to non-diabetics.
Reducing dietary carbohydrates therefore appears to be important in management of the breast cancer problem. Less carbohydrate intake is now being recommended to: (a) reduce risk of developing breast cancer; (b) slow breast cancer progression; (c) lower the risk of breast cancer recurrence after initial treatment; and (d) increase the probability of surviving breast cancer. With modern treatment, complete cure from breast cancer is achieved in about 50 per cent of cases. Cutting down on carbohydrate intake appears to have the potential of improving on these cure rates.
Until recently, dietary animal saturated fat (in meats and dairy produce) was blamed for increased breast cancer risk and for the much higher breast cancer rates in Western countries compared with Asia. Current thought suggests the Asian high legume consumption lowers breast cancer risk, while the high sugars and refined flour foods and low legume intake in Western countries raises this cancer risk (and also prostate).
Too much alcohol consumption is claimed to increase breast cancer risk, possibly because it may raise blood oestrogen, insulin and IGF-1. However, on the basis of current knowledge, moderate alcohol intake does not appear to be as important as carbohydrates for breast cancer risk.
Unfortunately, the staple Maltese diet is very rich in these unhealthy carbohydrates (sugars, white bread, pasta, pizza, white rice, pastries, potato). Changing one’s dietary preferences is notoriously difficult, but it is worth trying to eat more vegetables, legumes and less bread, pasta, white rice and potato. It is not appreciated enough that legumes (beans and lentils) contain much protein and are a complete food – excellent for diabetics, for reducing breast (and prostate) cancer risk and for general good health.
Prof. Cilia-Vincenti is a practising pathologist, a scientific delegate to the European Medicines Agency and a chairman of the Academy of Nutritional Medicine (London). He is a former lecturer at London and Malta universities.