08 September 2005
ByAppeared in BioNews 325
The US Preventive Services Task Force has published guidelines on assessing the risk of familial breast and ovarian cancer. It states that genetic counselling is only appropriate for women whose family history suggests they may have inherited a mutation in the BRCA1 and BRCA2 breast cancer genes. The recommendations were published in the Annals of Internal Medicine.
Most cases of breast cancer are not inherited, but around 5-10 per cent are due to a gene mutation. Women who have a mutation in either the BRCA1 or BRCA2 gene have a greatly increased lifetime risk of developing breast and ovarian cancer. However, since most women with breast cancer do not have a faulty BRCA1 or BRCA2 gene, screening populations for the mutations is not justified, says the task force.
The recommendations are similar to those issued by the UK's National Institute for Health and Clinical Excellence (NICE) last year. They list the family history patterns linked to a BRCA gene mutation: two first-degree relatives with breast cancer, one of whom was diagnosed before the age of 50; three or more close relatives diagnosed with breast cancer at any age; a close relative diagnosed with both breast and ovarian cancer; a close relative with cancer in both breasts; two or more close relatives with ovarian cancer; or a male relative with breast cancer.
The US panel also recommends that women of Ashkenazi Jewish descent with any one relative diagnosed with either breast or ovarian cancer should be referred for genetic counselling, since the disease is more common in this group. Around 2.5 per cent of people of Ashkenazi Jewish descent carry one of three common BRCA1/BRCA2 gene mutations.
An editorial accompanying the study said that the guidelines highlight the need for doctors to take a detailed family medical history of their patients. 'Taking a family history has long been considered an integral part of medical evaluation, but few clinicians gather the detailed information required', wrote Dr Wylie Burke, of the University of Washington.
The authors of the guidelines conclude that 'risk assessment, genetic counselling and mutation testing did not cause adverse psychological outcomes, and counselling improved distress and risk perception in the highly selected populations studied'. Risk assessment includes advice about possible options for women at high risk of breast or ovarian cancer, such as preventative surgery to avoid developing the disease. Research is also underway to find out if treating such women with tamoxifen or similar drugs can reduce the risk of developing the illness.