Epidemiological data breast cancer

Breast cancer is one of the most common forms of cancer affecting women and, in Western countries, the incidence is rising. The risk of breast cancer increases markedly with age, although a decrease in the rate occurs after the menopause, suggesting that development is hormone-dependent. To date, a number of hormone-related risk factors have been identified (Bingham et al, 1998). Countries such as Japan have relatively low rates of breast cancer, which have been associated with consumption of a diet high in soy foods. Currently, however, the data from epidemiological studies is inconclusive. 

The pattern of hormonal risk factors involved in the development of endometrial cancer is similar to those associated with the development of breast cancer. In addition, there is substantial evidence to suggest that HRT can increase the risk (Beral et al, 1999 Bingham et al, 1998). Compared to the UK, the incidence of endometrial cancer in countries such as Japan is relatively low (Bingham et al, 1998). It has been suggested that dietary factors may be responsible for the reduced incidence, and there is indirect evidence from epidemiology studies which suggests that increased consumption of soy products may lower the risk of endometrial cancer. However, these data are not conclusive. To date, no studies have demonstrated a link between consumption of phytoestrogens and an increased risk of endometrial cancer. 

Collaborative Group on Hormonal Factors in Breast Cancer (1997) Breast cancer and hormone replacement therapy collaborative reanalysis of data from 51 epidemiological studies of 52,705 women with breast cancer and 108,411 women without breast cancer. Lancet 350 1047-1059... 

In recent years breast cancer mortality has, if anything, shown a tendency to increase (40), indicating that current methods of treatment are having relatively little impact on this disease. The epidemiological data nevertheless show large differences in the mortality rates in different countries, which are strongly correlated with dietary fat in the food supplies. It is evident that new approaches are required to reduce the death toll from breast cancer in the more affluent countries of the world, and one way might be to reduce dietary fat intake as recently recommended by the NRC-NAS Committee on Diet, Nutrition and Cancer (14). 

Collaborative Group on Hormone Factors in Breast Cancer 1996 Breast cancer and hormonal contraceptives collaborative reanalysis of individual data on 53 297 women with breast cancer and 100 239 women without breast cancer from 54 epidemiological studies. Lancet 347 1703, 1713... 

In Europe, epidemiological data demonstrated that mortality from breast and colorectal cancer is considerable by lower in countries where olive oil consumption is high (such as Greece, Italy and Spain) than in those where the consumption is low (such as Scotland, England and Denmark) [45). 

The first hint about the role of polyphenols in cancer was obtained through analysis of epidemiologic data. Several studies showed that tea, soy, olive oil, and whole grains consumption significantly reduces the risk of certain types of cancer. A study by Sun et al. conducted in eight countries showed that tea consumption reduces the risk of breast cancer (Sun et al. 2005). In addition, a prospective study by Severson and coworkers (1989) demonstrated a positive relationship between soy consumption (as tofu) and a decreased risk of prostate cancer. A much broader epidemiologic study on men in 59 countries demonstrated that a diet... 

But even if one were to accept the epidemiologic data at face value and assume that the entire correlation was due to a causal link flowing in only one direction (from alcohol to breast cancer), how strong is that association anyway The largest study to bear on that question is the European Prospective Investigation into Cancer and Nutrition (EPIC). It examined data collected on self-reported alcohol consumption and cancer diagnoses in 274,688 middle-aged and elderly women from ten countries for up to 9.4 years (median 6.4 years). 

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