Abstract 173P
Background
Approximately 5-10% of breast cancer patients have hereditary causes and since the frequency of mutation in these genes is rare, it is not recommended to investigate mutations in every patient with breast cancer. NCCN recommends to examine the BRCA genes for mutation in certain patient groups diagnosed with breast cancer. The aim of this study is to determine the possibility of detecting BRCA mutation in Turkish breast cancer patients based on NCCN criteria.
Methods
This is a retrospective cohort study conducted among patients who were followed up with a diagnosis of breast cancer and were recommended to be evaluated for BRCA mutation by the NCCN between January 2015 and August 2019 in Hacettepe Cancer Institute. Patients who met any one of the criteria recommended by the NCCN to investigate the BRCA mutation were selected. All participants had results of gene analysis using both NGS and/or MLPA methods. Positive predictive value of each criteria is compared with treshold defined by the mutation risk prediction models as BRCAPRO and BOA-DICEA.
Results
Of the 636 breast cancer patients tested, a total of 139 (21.9%) pathogenic BRCA mutation carriers were detected. The median age at diagnosis was 41. IDC was the most common histological subtype (65.7%). We found pathogenic BRCA mutation in 9.3% patients who met only one of the NCCN criteria. A total of 410 patients (64.5%) were tested because of meeting two or more criteria. Detection of mutation rate were higher in patients who met more than one criteria than entire cohort. Detection of mutation rate was significantly higher in patients who met any one of the family history criteria than those who did not meet them (27.4% vs. 10.3%, p<0.001).
Conclusions
This study demonstrates that forclinicians counselling patients based on NCCN recommendations for BRCA gene analysis, detection of mutation rate is similar to that in the overall breast cancer population. BRCA gene analysis performed according to family history criteria in NCCN recommendations causes quite stringent criteria in the Turkish population. Considering all this information in terms of the differences between mutation detection rates; we conclude that using the family history critera in the NCCN recommendations is highly cost effective.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.