As with most cancers, the earlier breast cancer is diagnosed, the greater the chance of a cure. Stage 1 is a cancer in a very early stage; stage 4 is one which has already spread to many organs. In Britain the survival rates by stage of cancer development are: 84 per cent (stage 1), 71 per cent (stage 2), 48 per cent (stage 3), 18 per cent (stage 4).
Early Detection
Early detection is all-important. Research in Britain and Sweden has shown that small breast cancers—those less than 15 mm (1 in) in diameter—are less likely to have spread and are less aggressive. In 1994-1995, the National Breast Screening Programme identified 6,500 cancers, and 2,660 were smaller than 15 mm. Nearly 20 per cent of the cancers found had not become invasive, that is, they had not spread beyond the breast ducts. In the United Kingdom all women between 50 and 65 are invited to have a mammogram (breast X-ray) every three years through the National Breast Screening Programme; women over 65 are entitled to be screened on request. The programme aims to cut breast cancer deaths by 25 per cent in the screened population and it has a 77 per cent take-up rate.
Women are advised to practise self-examination between screenings or if they are under 50. Self-examination involves a monthly check for unusual lumps or other breast changes, such as nipple discharge or bleeding. At present, however, there is no clear evidence of the effectiveness of breast self-examination in reducing deaths from breast cancer. Nevertheless, the majority of breast cancers are found by the women themselves rather than through mammography screening. Many doctors believe that women should be made aware of breast cancer symptoms and encouraged to examine their breasts, or at least be aware of how they usually feel, so that any changes can be reported to their family doctor quickly.
Causes
Hormones
The female hormone oestrogen plays an important part in breast cancer development. The following factors may increase risk: starting menstruation (periods) early in life; late menopause; obesity after the menopause, as very overweight women produce more oestrogen; and having no children, or having a first child after 40 years old. Incidence in later life increases with a woman’s age at the time of her first pregnancy. It is around three times greater when the first birth is after 35 than when it occurs before 18.
Taking the contraceptive pill (see Birth Control) or hormone replacement therapy (HRT) may also have an impact.
In 1996, the largest overview on the Pill and breast cancer reported a small increased risk while taking the Pill. However, the risk decreased when women stopped taking it, and after ten years their risk was the same as for women not on the Pill.
There is no conclusive link between HRT use and breast cancer. So far, it seems that taking HRT drugs for up to five years is safe, but prolonged use may incur a small increased risk. Any risks associated with HRT have to be weighed against the benefits, which are decreased risk of serious disease, such as heart disease; osteoporosis (thinning of the bones); and possibly bowel cancer. A number of large studies are under way in Britain and the United States that may further clarify possible breast cancer risks of HRT.
Family History
About 5 per cent of breast cancers are linked to family history. The risk for a woman whose mother or sister had breast cancer is at least double that of someone with no family history. If her relatives were under 40 when diagnosed, her risk is even higher.
Two genes, BRCA1 and BRCA2, have been discovered to be involved in familial breast cancer, particularly in young women. A woman who has a fault in one of these genes has a high risk of developing breast cancer. It is possible that tests for mutations in these genes will be widely available in the near future. An international study is under way to see if giving the hormone-blocking drug tamoxifen to high-risk women, mainly those with a family history of the disease, will prevent them from developing breast cancer.
Diet
Diet may play a part in breast cancer. Studies indicate that girls who eat too much and take little or no exercise grow faster and reach puberty earlier, which is thought to increase breast cancer risk because of the production of oestrogen for longer period in life.
Recent studies have not upheld an early hypothesis that fat content in the diet is involved in breast cancer. There is some evidence that breast cancer rates could be lowered by including soya products in the diet.
Smoking
Whether or not smoking plays a part in breast cancer is a subject of much debate. Researchers reported in the United States in 1996 that smoking may be involved. They compared 324 breast cancer patients with 327 controls and discovered that post-menopausal smokers with mutations in a gene that helps the body get rid of carcinogens were four times more likely to get breast cancer than non-smokers.
However, a previous review of 50,000 breast cancers and 100,000 controls found no link between breast cancer and smoking. Some researchers have pointed out that this recent report involved a small number of cases and that the results could well be due to chance.
Treatment
Early Breast Cancer
Breast conservation therapy is suitable for about 80 per cent of cancers and involves removing the lump (lumpectomy) and the lymph glands under the arm (the first site breast cancer spreads to), followed by radiotherapy. Research has shown that this newer method is as effective as mastectomy (surgical removal of the breast), which still tends to be the main treatment for early breast cancer.
Women may also be offered other treatments afterwards. Prescribing the hormone-blocking drug tamoxifen for post-menopausal women, and offering ovarian ablation (stopping the ovaries from producing oestrogen) to younger women would save 1,000 extra lives a year in the United Kingdom. Ovarian ablation can be done by removing the ovaries, irradiating them, or prescribing certain drugs.
Advanced Breast Cancer
Treatment of advanced breast cancer, that is, cancer, which has spread, is usually aimed at giving the patient a manageable quality of life with the disease kept under control, rather than a cure. Conventional treatments include drugs which cut oestrogen levels, and various chemotherapy combinations. Some women have bone metastases that cause pain and fractures. They may be treated with a new drug, APD, which helps to alleviate symptoms.
There are many new treatments in the trial stages such as high-dose chemotherapy, targeting therapies, immunotherapies, and gene therapies. However, it will be several years before their efficacy is known.
