BRCA testing and Japanese original testing criteria for hereditary breast and ovarian cancer covered by public health insurance

Abstract In Japan, BRCA1/2 testing has been made available to the public as a companion diagnostic test for olaparib since July 2018. This testing indication has been expanded to diagnosis of hereditary breast and ovarian cancer. The Japanese breast cancer society (JBCS) issued original guidance and criteria to estimate eligibility for BRCA testing among breast cancer patients. This retrospective study aimed to evaluate the current Japanese situation of BRCA testing and the utility of JBCS criteria. We retrospectively reviewed medical records of 1,136 early breast cancer patients. The number of the patients who were eligible for BRCA testing based on JBCS criteria was retrospectively counted. The relationship between the six categories of JBCS and BRCA pathogenicity was evaluated using multivariate analysis. Among the entire cohort, 40.2% met at least one criterion. Being diagnosed with breast cancer at 45 years or younger of age, having two or more primary breast cancers, and being diagnosed with triple negative breast cancer at 60 years or younger significantly increased the likelihood of having BRCA mutation (OR: 8.8, 20.8, 8.6, respectively). In addition, the patients that met two or more testing criteria had higher rates of BRCA mutation than those that met only one criterion. This study suggests that approximately 40% of early breast cancer patients are potential candidates for BRCA testing and/or genetic counseling based on JBSC criteria. Prioritizing the six categories may make the criteria more applicable for use in the current Japanese clinical setting, as genetic practice has limited specialist human resources.