Impact of mainstream genetic testing for breast cancer patients: five-year data from the Parkville Familial Cancer Centre.

Mainstream genetic testing is a model of care where non-genetics health professionals arrange genetic testing for their patients directly. The Parkville Familial Cancer Centre (PFCC) provides a breast cancer mainstream program; initial two-year outcomes previously reported. With an evolving health landscape, the program has been refined with ongoing evaluation, and we now report on outcomes from the first five years of program operation. Program operation and refinement is outlined, including patient eligibility criteria and gene panel use during the study period. Demographics and outcomes for patients who underwent mainstream genetic testing between September 2017 and March 2022 have been analysed, as well as characteristics of the mainstream clinicians and uptake of genetic testing for at-risk relatives. During the study period, 657 patients underwent mainstream genetic testing at ten hospitals in Victoria, Australia. Pathogenic variant (PV) detection rate was 11.5%, and variant of unknown significance rate was 6.5%. A subset of PV carriers were further analysed, and 75.8% had a change in their treatment plan as a result of the PV. The PFCC saved 1,210 appointments due to the mainstream program. Demand for mainstream genetic testing is increasing, with eligibility criteria expanding. The PFCC mainstream program PV detection rate, PV proband relative cascade testing engagement and PFCC resources saved remain high, in line with other studies. Whilst mainstream models of care can evolve and be tailored, it is paramount that FCC-supported mainstream programs can be sustained as demand increases.