Person:

Kent, Michael

Introduction The identification of somatic genomic aberrations in non-small-cell lung cancer (NSCLC) is part of evidence-based practice guidelines for care of patients with NSCLC. We sought to establish the frequency and correlates with these changes in routine patient–tumor sample pairs.

Methods Clinicopathologic data and tumor genotype were retrospectively compiled and analyzed from an overall cohort of 381 patient–tumor samples.

Results Of these patients, 75.9% self-reported White race, 13.1% Asian, 6.5% Black, 27.8% were never-smokers, 54.9% former-smokers and 17.3% current-smokers. The frequency of EGFR mutations was 23.9% (86/359), KRAS mutations 34.2% (71/207) and ALK FISH positivity 9.1% (23/252) in tumor samples, and almost all had mutually exclusive results for these oncogenes. In tumors from White, Black and Asian patients, the frequencies of EGFR mutations were 18.4%, 18.2% and 62%, respectively; of ALK FISH positivity 7.81%, 0% and 14.8%, respectively; and of KRAS mutations 41.6%, 20% and 0%. These patterns changed significant with increasing pack-year history of smoking. In White patients, the frequencies of EGFR mutations and ALK FISH positivity decreased with increasing pack-year cohorts; while the frequencies of KRAS mutations increased. Interestingly, in Asian patients the frequencies of EGFR mutations were similar in never smokers and in the cohorts with less than 45pack-year histories of smoking and only decreased in the 45pack-year plus cohort.

Conclusions The frequencies of somatic EGFR, KRAS, and ALK gene abnormalities using routine lung cancer tissue samples from our United States-based academic medical practice reflect the diverse ethnicity (with a higher frequency of EGFR mutations in Asian patients) and smoking patterns (with an inverse correlation between EGFR mutation and ALK rearrangement) of our tested population. These results may help other medical practices appreciate the expected results from introduction of routine tumor genotyping techniques into their day-to-day care of NSCLC.

Introduction—Identification of some somatic molecular alterations in non-small-cell lung cancer (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 in a cohort of lung cancers subjected to routine clinical tumor genotype. Methods—Clinicopathologic data, tumor genotype success and failure rates were retrospectively compiled and analyzed from 381 patient-tumor samples. Results—From these 381 patients with lung cancer, the mean age was 65 years, 61.2% were women, 75.9% were white, 27.8% were never smokers, 73.8% had advanced NSCLC and 86.1% had adenocarcinoma histology. The tumor tissue was obtained from surgical specimens in 48.8%, core needle biopsies in 17.9%, and as cell blocks from aspirates or fluid in 33.3% of cases. Anatomic sites for tissue collection included lung (49.3%), lymph nodes (22.3%), pleura (11.8%), bone (6.0%), brain (6.0%), among others. The overall success rate for EGFR mutation analysis was 94.2%, for KRAS mutation 91.6% and for ALK FISH 91.6%. The highest failure rates were observed when the tissue was obtained from image-guided percutaneous transthoracic core-needle biopsies (31.8%, 27.3%, and 35.3% for EGFR, KRAS, and ALK tests, respectively) and bone specimens (23.1%, 15.4%, and 23.1%, respectively). In specimens obtained from bone, the failure rates were significantly higher for biopsies than resection specimens (40% vs 0%, p=0.024 for EGFR) and for decalcified compared to non-decalcified samples (60% vs 5.5%, p=0.021 for EGFR). Conclusions—Tumor genotype techniques are feasible in most samples, outside small imageguided percutaneous transthoracic core-needle biopsies and bone samples from core biopsies with decalcification, and therefore expansion of routine tumor genotype into the care of patients with NSCLC may not require special tissue acquisition or manipulation.

Introduction

Tumor genotyping using single gene assays (SGAs) is standard practice in advanced non-small-cell lung cancer (NSCLC). We evaluated how the introduction of next generation sequencing (NGS) into day-to-day clinical practice altered therapeutic decision-making.

Methods

Clinicopathologic data, tumor genotype, and clinical decisions were retrospectively compiled over 6 months following introduction of NGS assay use at our institution in 82 patient-tumor samples (7 by primary NGS, 22 by sequential SGAs followed by NGS, and 53 by SGAs).

Results

SGAs identified abnormalities in 34 samples, and all patients with advanced EGFR-mutated or ALK-rearranged tumors received approved tyrosine kinase inhibitors (TKIs) or were consented for clinical trials. NGS was more commonly requested for EGFR, ALK, and KRAS-negative tumors (p<0.0001). NGS was successful in 24/29 (82.7%) tumors. Of 17 adenocarcinomas (ACs), 11 (7 from patients with ≤15 pack-years of smoking) had abnormalities in a known driver oncogene. This led to a change in decision-making in 8 patients, trial consideration in 6, and off-label TKI use in 2. Of 7 squamous cell (SC) carcinomas, 1 had a driver aberration (FGFR1); 6 had other genomic events (all with TP53 mutations). In no cases were clinical decisions altered (p=0.0538 when compared to ACs).

Conclusions

Targeted NGS can identify a significant number of therapeutically-relevant driver events in lung ACs; particularly in never or light smokers. For SC lung cancers, NGS is less likely to alter current practice. Further research into the cost effectiveness and optimal use of NGS and improved provider training in genomic oncology are warranted.