A new paper in the American Journal of Medical Genetics reports the results of an investigation into how BRCA1/2 genetic testing alters the perception of breast and ovarian cancer risk in high-risk families [McInerney-Leo A et al. (2006) Am J Med Genet A. 140A, 2198-2206]. Individuals with a strong family history of cancer tend to overestimate personal risk; genetics education and counselling is intended to improve the accuracy of this risk perception (and hence create a reduction in anxiety and psychological distress along with appropriate health behaviours, such as increased adherence to screening programmes for those at genuinely high risk). However, the authors say that less is known about the effect of genetic testing on risk perception, particularly among members of high-risk breast and ovarian cancer families. They therefore recruited a total of 138 women from thirteen families, of which 87% chose to be tested for a known familial mutation.
Risk perceptions were assessed using a questionnaire before and after receiving genetic test results. The initial (baseline) risk perception was generally high, with 75% of women appropriately considering themselves to be a higher risk of developing breast cancer and ovarian cancer than other women their age. There was no difference in risk perception between those choosing testing and those declining testing. Following testing, 24% of participants were identified as mutation carriers; this did not affect their breast cancer risk perception but did increased their perception of ovarian cancer risk. Those testing negative had a significant decrease in all dimensions of risk perception. Interestingly, women who declined genetic testing showed significant reductions in their perceived risk of ovarian cancer and of carrying a mutation, although their breast cancer risk perception was not affected. It was found that seven out of eighteen of these women had had a parent who tested negative for the familial mutation, and in these cases the reduction in perceived risk was consistent with a decrease in actual risk.
The authors assert that their findings “demonstrate the significant impact genetic test results can have on perceived risk”, and contrast their observed modification of risk perception created by genetic testing with less successful attempts to improve accuracy of risk perception in similar high-risk populations through education and counselling. They propose that genetic tests may have an additional value for high-risk patients than information based upon family history alone, and suggest further research to determine whether this might apply to different forms of familial cancer and other diseases.
Comment: The finding that women can “successfully understand and integrate their genetic test results” is a positive one, but unsurprising given that the study population was highly educated and had significant prior interest in genetic testing. The study failed to demonstrate significant associations between perceived risk and follow-up screening practices, although as all the study participants had family histories of breast and ovarian cancer, it is probable that their adherence to screening programmes was already high. The effect of mutation testing on measures of psychological and emotional distress is not discussed. The study is therefore of limited utility, since in addition to the issue of whether genetic testing accurately modifies risk perception, the key question that remains is: does this alteration in risk perception as a result of genetic testing have health benefits for the individual, in terms of improved compliance with appropriate screening and/or emotional well-being?