Mutational Screening of BRCA1/2 Genes as a Predictive Factor for Therapeutic Response in Epithelial Ovarian Cancer: A Consensus Guide from the Spanish Society of Pathology (SEAP-IAP) and the Spanish Society of Human Genetics (AEGH)

Abstract

Germline/somatic BRCA-mutated ovarian carcinomas (OC) are associated to have better response with platinum-based chemotherapy and long-term prognosis than non-BRCA-associated OCs. In addition, these mutations are predictive factors to response to Poly(ADP-ribose) polymerase (PARP) inhibitors. Different positioning papers have addressed the clinical recommendations for BRCA testing in OC. This consensus guide represents a collection of technical recommendations to address the detection of BRCA1/2 mutations in the molecular diagnostic testing strategy for OC. Under the coordination of Spanish Society of Pathology (SEAP-IAP) and the Spanish Society of Human Genetics (AEGH), these recommendations have been developed by pathologists and geneticists taking into account previously published recommendations and their experience in the molecular characterization of these genes. Since the implementation of BRCA testing as a predictive factor can initiate the workflow by testing germline mutations in the blood or by testing both germline and somatic mutations in tumor tissue, distinctive features of both strategies are discussed. Additionally, the recommendations included in this paper provide some references, quality parameters, and genomic tools aimed to standardize and facilitate the clinical genomic diagnosis of OC.

Feasibility of BRCA1/2 Testing of Formalin-Fixed and Paraffin-Embedded Pancreatic Tumor Samples: A Consecutive Clinical Series

“…On the other hand, biopsies and cell-blocks had an overall low fragmented DNA, and standard tissue sections from surgical resections had a medium DNA fragmentation level. This confirms how crucial it is for the molecular pathology laboratory to carefully check for pre-analytical conditions and particularly for fixation type and time [21].…”

“…The use of an amplicon based method for BRCA1/2 testing, which usually requires less DNA input in comparison to hybrid capture strategy [21], allowed us to also analyze samples with a suboptimal DNA yield. Good NGS quality metrics were reported for 26 out of 32 specimens with a success rate of 81.2%.…”

“…Moreover, Mohyuddin and collaborators in a recent meta-analysis found that outcomes for patients with somatic BRCA1/2 mutations treated with PARP inhibitors appear similar to those of patients with germline alterations [20], thus suggesting that somatic mutations should be evaluated as well as germline ones. In this scenario, negative germline reports may advise a tumor study for the determination of somatic variants [21] and the possibility to perform BRCA1/2 testing on tumor tissues would allow us to detect both germline and somatic alterations.…”

Genotyping data of routinely processed matched primary/metastatic tumor samples

“…The TCC% values obtained either way may greatly differ, as exemplified in Fig. 1 B and 1 C. Because of such differences in TCC% assessment, the marker has been considered as unreliable over the years, difficult to communicate to biologists and clinicians [2] and is not obligatorily included in the recommendations for genotyping reports (e.g., by the Spanish pathologists and geneticists [3] ). However, TCC% is important not only for determining the eligibility of tumor samples for molecular studies relevant to method sensitivity, but also for interpreting profiling and genotyping results [ 2 , 4 , 5 ].…”

Tumor Genotyping and Homologous Recombination Repair Gene Variants in Patients With Epithelial Ovarian Cancer: Is Pathogenic Enough?

“…The presence of a pathogenic BRCA1/2 or any HRR gene mutation in a tumor is not synonymous and interchangeable with HRD, and it does not necessarily signify a non-functional gene status ( 22 , 23 ). Guidelines for reporting and interpreting the clinical relevance of e.g., BRCA1/2 variants in tumors usually focus on the accurate annotation of variant pathogenicity and on increasing the sensitivity of variant detection, by taking into account the variant load ( 24 , 25 ), or without such consideration ( 26 ). However, a higher rate of a pathogenic allele in a tumor would indicate the presence of a clonal alteration driving tumor evolution ( 27 ) and in the case of HRR genes, loss of function.…”