Genetic testing for BRCA1: effects of a randomised study of knowledge provision on interest in testing and long term test uptake; implications for the NICE guidelines

Abstract

Introduction Interest in searching for mutations in BRCA1 and BRCA2 is high. Knowledge regarding these genes and the advantages and limitations of genetic testing is limited. It is unknown whether increasing knowledge about breast cancer genetic testing alters interest in testing. Methods Three hundred and seventy nine women (260 with a family history of breast cancer; 119 with breast cancer) from The Royal Marsden NHS Foundation Trust were randomised to receive or not receive written educational information on cancer genetics. A questionnaire was completed assessing interest in BRCA1 testing and knowledge on breast cancer genetics and screening. Actual uptake of BRCA1 testing is reported with a six year follow-up. Results Eighty nine percent of women at risk of breast cancer and 76% of women with breast cancer were interested in BRCA1 testing (P < 0.0001). Provision of educational information did not affect level of interest. Knowledge about breast cancer susceptibility genes was poor. According to the NICE guidelines regarding eligibility for BRCA1 and BRCA2 testing, the families of 66% of the at risk group and 13% of the women with breast cancer would be eligible for testing (probability of BRCA1 mutation ≥20%). Within six years of randomisation, genetic testing was actually undertaken on 12 women, only 10 of whom would now be eligible, on the NICE guidelines. Conclusions There is strong interest in BRCA1 testing. Despite considerable ignorance of factors affecting the inheritance of breast cancer, education neither reduced nor increased interest to undergo testing. The NICE guidelines successfully triage those with a high breast cancer risk to be managed in cancer genetics clinics.

Appendix

Those randomised to receive written educational information in this study received the following:

You may have heard about a gene called BRCA1 that is carried by a small number (approximately 2–3%) of women who have breast cancer. The chance of having had breast cancer as a result of the inheritance of an alteration in this gene is therefore quite low, but it is higher if the breast cancer has occurred at a younger age. Usually these women have a family history of the disease; however, not all families with breast cancer have this gene. It is believed that this gene may be passed from one generation to the next in these affected families. In these families, some family members will inherit the gene and others will not. Both men and women have an equal chance of inheriting and passing on this gene.

A woman who has the gene has a high risk of developing breast cancer (80–90%) during her lifetime. Women who carry the BRCA1 gene, with family histories of breast and ovarian cancers, have an increased risk for developing both cancers. A person with the BRCA1 gene has a 50% chance of passing this gene on to each child. A woman who is not a gene carrier but is in one of these families where BRCA1 is present has the same risk of developing breast cancer as a woman with no family history of breast cancer. She should therefore, have the screening offered to the rest of the population. Women who carry the gene can be offered several options. All of these are not yet proven to reduce cancer risk. These are: early screening by mammography (for breast cancer) and ultrasound (for ovarian cancer), drug prevention using Tamoxifen or removal of breast and/or ovarian tissue.

It will shortly become possible to offer the BRCA1 breast cancer gene test to a small number of people in very high risk families; however, it is not possible at this time to test numerous individuals to see if they are carrying the gene (BRCA1) for breast cancer. However, in the near future (over the next 2 years), a blood test to determine which family members have this gene will become more widely available.