ABSTRACT
Breast cancer is the commonest malignancy found in women in Europe and the United States, and the incidence continues to rise slowly. In 2004, there were 44,000 new incident cases of breast cancer diagnosed in the United Kingdom. Breast cancer accounts for 31% of cancer diagnoses in the female population, compared with colorectal (12%), lung (11%), and ovarian carcinoma (5%). In 2005, breast cancer accounted for 17% of cancer deaths, slightly fewer than lung cancer which accounted for 19% of cancer deaths. In the United States, over 180,000 new cases of invasive breast cancer are diagnosed each year (1,2). The incidence rate in Western Europe and North America is approximately 50 to 60 per 100,000 women, and the mortality rate is of the order of 15 to 25 per 100,000 women, that is 30% to 40% of the incidence rate. There are marked geographical variations in incidence. The highest rates have been observed in Hawaii, California, and British Columbia. Slightly lower rates are seen in western Europe. Indian, African, and Chinese women have intermediate incidence rates of the disease, while the low incidence rates previously reported in Japan are now increasing. Within Europe, incidence rates decrease from north to south and from west to east. Within each country breast cancer incidence correlates with the per capita income of the population in various districts. Studies conducted on migrant populations have shown that the incidence rate converges with that of the indigenous population within two generations, confirming the importance of environmental factors (3).
