Genetic counselling and gene testing in genetic units

In women who need predictive genetic testing, genetic counselling should be offered which covers the nature of hereditary breast and ovarian cancer, the purpose and interpretation of gene testing, and the implications. The protocol for testing involves testing an affected family member first.

When an alteration is identified in the relevant gene, this could then be used to offer testing for other family members. However, it has been shown that testing identifies an alteration in a gene in only 30% of families with affected family members where the risk is more than 20%. Female family members who are not found to be carrying an altered gene are deemed to have the general population level of risk of developing breast or ovarian cancer.

If an alteration in the breast-cancer-causing gene is not determined in affected individuals, then testing of other family members is not available and management should be according to family history.

Surgery: the role of prophylactic mastectomy and oophorectomy

Women who are considering risk-reducing surgery should be under the care of a specialist genetics centre. The options that are available to women who are at high risk of developing either breast cancer or ovarian cancer include bilateral mastectomy, and oophorectomy. A full risk assessment and verification of the family history is necessary. It is important that the counselling process is appropriate, and that a multidisciplinary team is involved in providing psychological support and assessment. Both types of surgery are offered to a small proportion of women at risk, carrying altered BRCA1, BRCA2 and TP53 genes.

Neither procedure completely eradicates the risk of disease. Prophylactic oophorectomy reduces the relative risk of breast cancer by up to 50% in families with known carriers of altered BRCA1 or BRCA2 genes, and reduces the risk of ovarian cancer by 95%. Bilateral mastectomy gives a relative risk reduction of 95% in the lifetime risk of developing breast cancer. Clearly, the potential complications of surgery and morbidity need to be taken into account, and women do need to be prepared psychologically prior to surgery.

Breast cancer risk factors in women with a positive family history

When advising women about HRT to counteract menopausal symptoms, they should be made aware that HRT use should be minimised because of the increase in breast cancer risk (particularly with more than 5 years' use of HRT). Similarly, although the oral contraceptive pill protects against ovarian cancer, there is an increase in breast cancer risk after the age of 35 years. General lifestyle advice includes weight reduction, avoidance of excessive alcohol intake, and attention to the benefits of exercise and breastfeeding.

 
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