Introduction

Globally, breast cancer is the most frequent malignancy among women with an estimated 572,000 new cases in 1980 or 18.4% of all cancers. The disease is extremely rare in males: in females it shows marked geographical variation.

Histology, classification and diagnosis

Most breast tumors arise from the ductal or lobular epithelial cells. A number of histological subgroups are described which, in general, do not appear to have etiological relevance although differences in biological behavior between Japanese and North American women have been reported. Breast biopsies have increased with growth of mammography with a resultant rise in the diagnosis of borderline in situ lesions which complicates interpretation of incidence and mortality trends. Mortality is also influenced by newer therapeutic techniques. The risk of cancer developing in patients with benign breast disease is directly related to the degree of epithelial atypia. While hormonal receptors appear significant for prognosis, they appear to be unrelated to specific risk factors.

Descriptive epidemiology

Incidence and mortality

The highest rates occur in North America, Israel and temperate South America (over 60). High rates (40-60) are also seen in north western Europe and in Australia. Intermediate rates (20–40) are found in parts of Eastern Europe, tropical South America, Philippines and Singapore. Low rates (less than 20) are seen in China, parts of Japan and India and in Kuwaitis. In the USA rates are higher in whites than in blacks.