Incidence of breast cancer

Approximately 25,000 women develop breast cancer annually in the U.K. and although the cure rate has significantly improved in the last decade or two, nevertheless, many women still die from this disease each year in the U.K. That modern early intervention (surgery, radiotherapy hormone and chemotherapy can influence the overall cure rate in this disease has transformed optimal mangement and enhanced the early 'up front' approach now practised in oncology.

 

The age specific incidence rate rises by a factor of four as the age rises from 35 to 70 years and by the age of 80 there is a 1 in 12 chance for women develop this disease. Male breast cancer accounts for less than 1% of all cases.

 

There are racial differences in the incidence, and the Western world has a much higher incidence than is experienced in the Far East or Africa. Many of the other observed risk factors relate to prolonged unopposed oestrogen exposure. Thus, there is a statistically higher incidence of the disease in single, nulliparous (never been pregnant) women or those whose first pregnancy is beyond thirty years of age. Similarly, an early menarche (the initiation of menses/ovarian function) and a late menopause (the cessation of ovarian function – active oestrogen secretion) is associated with a higher incidence of breast cancer.

 

A history of proliferative benign breast disease is a predisposing factor although some patterns (e.g. atypical epitheliosis) are more sinister in their predisposing influence than others.

 

A history of breast cancer in one breast is predisposing to the development of a cancer in the other breast and this is particularly true for lobular cancer – vide infra.

 

A positive family history of breast cancer, particularly several first degree relatives developing the disease (perhaps in association with ovarian cancer) at an early age suggests a genetic origin, and this may account for perhaps 5(-10)% of all cases; there is also a slightly increased in risk in families for whom such a strong relationship in first degree relatives is not apparent but, nevrhteless there are one or ttwo relatives who have developed the disease.