Success and failure rates of tumor genotyping techniques in routine pathologic samples with non-small cell lung cancer.

Abstract

8050 Background: Identification of somatic molecular alterrations in NSCLC has become evidence-based practice. The success and failure rate of using commercially-available tumor genotyping techniques in routine day-to-day NSCLC pathology samples is not well described. We sought to evaluate the success and failure rate of EGFR mutation, KRAS mutation and ALK FISH. Methods: Clinicopathologic data, tumor genotype success and failure rates were retrospectively compiled and analyzed from 381 patient-tumor samples sent for routine tumor genotype in clinical practice. Results: Mean age was 65, 61.2% women, 75.9% white, 27.8% never-smokers, 73.8% had advanced NSCLC and 86.1% adenocarcinoma histology. Tumor tissue was obtained from surgical biopsies in 48.8%, core biopsies in 17.9% and as cell blocks from aspirates/fluid in 33.3%. Anatomic sites for tissue collection included lung (49.3%), lymph nodes (22.3%), pleura (11.8%), bone (6.0%), brain (6.0%), among others. In the 207 tumors in which the three tests were ordered concurrently, the success rate for EGFR was 92.3%, for KRAS 91.8% and for ALK FISH 89.9%. The highest failure rates were observed when the tissue was obtained from core biopsies (30.8%, 20.5% and 30.8% for EGFR, KRAS and ALK tests, respectively) and bone specimens (23.1%, 15.4% and 23.1% for EGFR, KRAS and ALK tests, respectively). In specimens obtained from bone, the failure rate was significantly higher in non-surgical than surgical specimens (40% vs 0%, p=0.024 for EGFR) and decalcified than non-decalcified samples (60% vs 5.5%, p=0.021 for EGFR). Conclusions: The success rate of multiple tumor genomic analyses techniques for EGFR, KRAS and ALK gene abnormalities using routine lung cancer tissue samples was ~90%. The highest failure rates occurred in tumors obtained from core biopsies and in bone samples from core biopsies with decalcification; specimens that may need to be scrutinized before submission to molecular studies. Tumor genotype techniques are feasible in most other samples obtained with current tumor acquisition methods, and therefore expansion of routine tumor genotype into the care of patients with NSCLC may not require special tissue acquisition or manipulation.