Cost-effectiveness of predictive genetic tests for familial breast and ovarian cancer

Aim: To examine the relative cost-effectiveness of predictive genetic tests for familial breast and ovarian cancer provided by Genetic Services of Western Australia. Methods: The relative cost-effectiveness was assessed using a decision analytic model. Results: The cost and outcomes of genetic testing was compared in first-degree relatives of known BRCA1/2 mutation-carriers who have a 50% risk of carrying the mutated gene (intervention group) to individuals with the same a priori risk but who do not undergo a genetic test (control subjects). Since genetic testing enables the restriction of intensive surveillance to individuals with an identified BRCA1/2 gene mutation, net savings in the period observed (age 25-70) were $980-$1008 per woman in the ovarian intervention group and $1681$1795 per woman in the breast intervention group, and delayed the onset of breast cancer (6mths BRCA1, 3mths BRCA2). Compared to control subjects undergoing population surveillance, it was estimated the onset of breast cancer could be delayed at a total net cost of $3055 (5.1yrs) to $3389 (3.2yrs) for women in the breast intervention group with BRCA1/2 mutations. Since population surveillance is not currently recommended for ovarian cancer, control subjects undergoing no surveillance were compared with the intervention group. The onset of ovarian cancer was delayed at a net cost of $1630 (3.5yrs) to $2509 (1.2years) for women with BRCA1/2 mutations. Conclusions: Testing allows targeted high-level surveillance for gene mutation carriers, which ensures the cost-effective use of resources and reduces cancer-related morbidity if clinical recommendations for intervention are adopted. Genomics, Society and Policy, Vol.1 No.2 (2005) ISSN: 1746-5354 © CESAGen, Lancaster University, UK. Genomics, Society and Policy 2005, Vol.1, No.2, pp.67–79. _____________ 68 Introduction Inherited predisposition to cancer is thought to account for 5-10% of all cancer incidence. Advances in genetic testing technology have many promising applications in health including improved diagnosis of disease and the earlier detection of genetic predisposition to adult-onset conditions, such as familial cancer. This will have important implications for resource allocation given the capacity to compare costs with associated benefits. Economic evaluation helps determine the relative value of new technology and enables better planning for the provision of future cancer genetic services. In order to understand the relative cost-effectiveness of genetic testing the prevalence and penetrance of the gene mutation must be considered as well as the uptake and efficacy of available interventions to prevent or detect cancer early. Reported benefits resulting from increased surveillance in women with a mutated BRCA gene have included earlier detection of breast cancer and an expected mortality reduction in women less than 50 years of age. There is also evidence that prophylactic intervention, such as bilateral mastectomy, has been associated with a reduction in the incidence of breast cancer of at least 90%. Though there is evidence to suggest oophrectomy reduces risk of breast cancer, it is not within the scope of this study. The absence of reliable surveillance methods for the early detection of ovarian cancer, and the poor prognosis following symptomatic presentation, have prompted many oncologists to recommend bilateral prophylactic salpingo-oophorectomy after childbearing. Furthermore, studies have validated the prophylactic role of surgical intervention and provided a convincing rationale for genetic testing in women with a strong family history. This study aimed to evaluate the relative costs and outcomes of genetic testing for familial breast and ovarian cancer through Genetic Services of Western Australia (GSWA). The investigation included familial breast and ovarian cancers suitable for predictive DNA based testing on the basis of inherited BRCA 1/2 mutations. The theoretical cohorts simulated asymptomatic first-degree relatives of individuals with a known BRCA1/2 mutation, who had a 50% chance of inheriting the cancerpredisposing gene mutation. Since reliable age and gene-specific cancer mortality data were not available at the time of modelling for relevant population subgroups, the impact of genetic testing and increased surveillance on mortality was not explored in this study. Instead the study focus was confined to the impact of genetic testing and increased surveillance on reduced cancer morbidity and, accordingly ‘cancer-free years’ was the most appropriate method to measure and report reduced cancer morbidity.