Profiling uptake of single site testing (SST) for familial cancer (CA) risk in an administrative genetic testing database.

Abstract

1550 Background: Among the anticipated social and cost-saving benefits to identifying a mutation in a CA predisposition gene in an individual is the subsequent opportunity to perform SST in close relatives to confirm risk status and to guide risk-reducing interventions. Despite ample research into uptake of primary genetic testing for Lynch syndrome (LS) and hereditary breast ovarian syndrome (HBOS) among moderate- and high-risk individuals, few studies have focused on the resultant cascade of SST that is predicted to follow in families. Methods: Administrative data on 2,631 consecutive single-site mutation tests performed over a 3-month interval (12/1/10-2/28/11) were obtained from a commercial genetic testing database maintained by Myriad Genetic Laboratories. 14 subjects (29 tests) were excluded due to multiple entries. Demographic, personal/family history (hx), and provider data are collected on a Test Requisition Form included in kits. All statistical tests are 2-sided (α=0.05). Results: Women had SST more often than men (HBOS 82.8%; LS 65.5%). Mean age at time of SST was 42.7 yrs, and was higher for HBOS than LS (p=0.01). Among subjects with hx of CA, mean age at CA diagnosis (dx) was similar (HBOS 48.6; LS 48.7 yrs). Subjects reported CA in >1 relatives (range 1-16) with a mean age at dx 40.1 yrs. Compared to HBOS, those tested for LS were more likely to report CA in a 1st degree relative (81.3 vs 74.4%, p=0.001) and a lower age of youngest CA dx in the family (p<0.001). Non-European ancestry was more common for HBOS SST than LS (30.0 vs 24.8%) (p=0.05). SST positive test rate was no different by syndrome or ancestry, but was higher for men (47.5 vs 42.0%, p=0.02). Conclusions: Uptake of commercial SST in high-risk families is uneven by age, sex, ancestry and CA syndrome. While between-syndrome variability in CA risks may explain some differences, more research is needed to understand barriers to uptake of SST among at-risk individuals if CA prevention goals are to be realized. [Table: see text]