The uptake of predictive DNA testing in 40 families with a pathogenic BRCA1/BRCA2 variant. An evaluation of the proband-mediated procedure.

When hereditary breast and ovarian cancer (HBOC) due to a BRCA1/BRCA2 germline pathogenic variant is diagnosed, the proband will be asked to inform other at-risk family members. In the Netherlands, a guideline was introduced in 2012 which provided detailed recommendations regarding this proband-mediated procedure. We now evaluated the uptake of predictive BRCA1/BRCA2 testing in 40 consecutive HBOC families diagnosed in our centre in 2014. We performed a retrospective observational study of all 40 families in which a pathogenic BRCA1/BRCA2 germline variant was identified during 2014. We scored the uptake of predictive and confirmatory testing by the end of 2018 and explored factors associated with the level of uptake. Two families were excluded. In the remaining 38 families, among 239 family members ≥18 years at 50% risk of being a mutation carrier or at 25% risk if the family member at 50% risk was deceased, 102 (43%) were tested. Among 108 females 25-75 years of age at 50% risk, 59 (55%) underwent predictive or confirmatory testing, and among 43 males at 50% risk with daughters ≥18 years, 22 (51%) were tested. Factors which complicated cascade screening included family members living abroad, probands not wanting to share information and limited pedigree information. In conclusion, the standard proband-mediated procedure of informing relatives seems to be far from optimal. We suggest a tailored approach for each family, including the option of a direct approach to at-risk family members by the geneticist. In addition, we suggest detailed monitoring and follow-up of families.