While most studies show a higher body mass in Western women to be positively associated with an increased breast cancer risk in postmenopausal women, they show a negative association in the case of premenopausal women. A review of case-control and cohort studies suggest that such protection applies mainly to obesity in teenage girls, whereas obesity appearing after the teenage years is more likely to be associated with a higher risk of postmenopausal breast cancer. The mechanisms are uncertain. There is evidence that obesity and the components of the Western diet can independently provoke hyperinsulinaemic insulin resistance at puberty, and in adolescent girls this has been related to evidence of abnormal ovarian steroidogenesis and anovulation. This may decrease promotion of mammary carcinogenesis. If however, obesity continues after the teenage years, the higher concentration of insulinlike growth factor 1 (IGF1) associated with hyperinsulinaemia can interact with oestrogen receptors in mammary epithelium to lead to increased proliferative activity.This review postulates that the observed protective effect of early obesity against premenopausal breast cancer is likely to be replaced by an increased risk of postmenopausal breast cancer if obesity continues after the teenage years. The manifestation of breast cancer is merely postponed to an older age. Recent prospective and case-control studies suggest that increased bioavailability of IGF1 is a marker of increased breast cancer risk in premenopausal women. Nutritional intake in early life may programme later activity in the growth hormone ± IGF1 axis and in¯uence the progression of transformed cells in mammary tissue. The question remains whether deliberate weight loss can reverse the effects of weight gain.

According to our survey in Yangbajing, Tibetan adults aged 40 years and older living at high altitudes had high BP and prevalence of hypertension with low awareness, treatment, and control. Future studies are needed to clarify the association between BP, altitude, and other possible causes.

Our findings suggest that hyperhomocysteinaemia may be associated with diabetic retinopathy and partially explain the increased risk of microvascular angiopathy occurring in these patients.

Objective: The incidence of breast cancer in the Western world runs parallel to that of the major components of the insulin resistance syndrome Ð hyperinsulinaemia, dyslipidaemia, hypertension and atherosclerosis. Evidence is reviewed that the growth of breast cancer is favoured by speci®c dietary fatty acids, visceral fat accumulation and inadequate physical exercise, all of which are thought to interact in favouring the development of the insulin resistance syndrome. Design: Clinical, epidemiological and experimental studies linking breast cancer risk with evidence of insulin resistance and its concomitants, were searched for in the MEDLINE database since 1985. Results: Clinical and epidemiological evidence suggests that both breast cancer and the metabolic disorders comprising the insulin resistance syndrome are polygenic and multifactorial in origin. Experimental evidence suggests that hyperinsulinaemia and its concomitants can increase the promotion of mammary carcinogenesis and the mechanism is likely to involve increased bioactivity of insulin-like growth factor 1 (IGF-1). Case-control and cohort studies have shown that higher serum levels of IGF-1 are associated with increased breast cancer risk. Pharmacological agents which lower IGF-1 concentrations are under clinical trial for breast cancer prevention. Conclusions: Nutritional and lifestyle modi®cations that improve insulin sensitivity may not only decrease a tendency to atherosclerosis but also reduce breast cancer risk in women. In addition to a reduced fat intake, the dietary regimen might involve a reduced n-6/n-3 ratio of polyunsaturated fatty acids and should be associated with avoidance of obesity and regular physical exercise. Interventions to decrease breast cancer risk in ®rst-degree relatives of breast cancer patients need to begin at an early age.