Genetic testing for breast cancer—adherence, outcomes and impact on surgical management: a quality review

Abstract

Hereditary breast cancer accounts for approximately 10% of all breast cancer cases. Swedish national breast cancer guidelines specify criteria for germline genetic testing. This quality review aimed to investigate the adherence to these criteria at diagnosis of breast cancer, the prevalence of pathogenic variants and the impact on surgical management. All patients diagnosed with primary breast cancer between July 2023 and June 2024 at Karolinska University Hospital were identified through the Swedish National Quality Register for Breast Cancer. Clinical data was collected from medical records for four groups fulfilling testing criteria: age £40 years, age ≤50 years with bilateral breast cancer or strong family history, patients with triple negative breast cancer (TNBC) and male patients. Among 630 identified patients, 138 (22%) met at least one testing criterion. Gene panel testing was completed for 114 patients (87%), and pathogenic variants were detected for 13/114 (11%). Variants were most frequently detected in patients with TNBC (15%), followed by those aged ≤50 years with bilateral disease or strong family history (11%) and those aged ≤40 years (7%), while no variants were found in the male patient. CanRisk risk prediction was performed for 47/114 tested patients (41%). Genetic findings and risk assessment by CanRisk led to modified primary surgical management for 15 patients, with bilateral mastectomy performed in 14 of these cases. Adherence to national guidelines for genetic testing was high. Pathogenic variants were identified in 11% of the patients, and the results had a substantial impact on surgical decision-making.