Sample Features Associated with Success Rates in Population-Based EGFR Mutation Testing

Preanalytic parameters in epidermal growth factor receptor mutation testing for non-small cell lung carcinoma: A review of cytologic series

The results from molecular assays can be affected significantly by the preanalytic condition of cytologic samples. The authors review current knowledge on the use of cytologic samples for epidermal growth factor receptor (EGFR) mutation testing in non–small cell lung cancer with a focus on preanalytic parameters. A systematic electronic search of the MEDLINE database was performed to identify original articles that reported the use of cytologic samples for EGFR molecular analysis and included a minimum of 100 samples. The information collected included author(s), journal, and year of publication; number of patients and samples; sampling method; type of preparation; type of fixative; staining techniques; mutation analysis techniques; tumor cellularity; the percentage of tumor cells; data on DNA quantity, quality, and concentration; failed assays; and the mutation rate. EGFR mutation analysis was conducted on 4999 cytologic samples from 22 studies that fulfilled the inclusion criteria. Fine‐needle aspirates and pleural effusions were the most common types of specimens used. DNA was mainly extracted from cell blocks and smears, and the most commonly reported fixatives included formalin, ethanol, and CytoLyt. Cellularity assessments and DNA yields were available from 5 studies each. The average success rate for the assays that used cytologic specimens was 95.87% (range, 85.2%‐100%). The mutation rate ranged from 6% to 50.46%, and a higher mutation detection rate and lower numbers of insufficient cases were reported for pleural effusions and lymph node samples from endobronchial ultrasound‐guided transbronchial needle aspiration compared with histologic specimens. Low cellularity and a low percentage of tumor cells were associated with higher test failure rates. Future guidelines should consider the current data for specific recommendations regarding cytologic samples. Cancer (Cancer Cytopathol) 2015;123:633–643. © 2015 American Cancer Society.

Preanalytic parameters for epidermal growth factor receptor mutation testing are reviewed in non–small cell lung cancer using 4999 cytologic samples from 22 studies. A higher mutation detection rate and lower numbers of insufficient cases are observed for pleural effusions and lymph node samples obtained using endobronchial ultrasound‐guided transbronchial needle aspiration compared with histologic specimens, and low cellularity and a lower percentage of tumor cells are associated with higher test failure rates. Future guidelines should consider the current data for specific recommendations regarding cytologic samples.

Ready or not? Lung cancer diagnosis in 2015

Lung cancer remains a significant health issue in Canada, with more than 26,000 new cases reported in 2014 [...]

The suitability of small biopsy and cytology specimens for EGFR and other mutation testing in non-small cell lung cancer

BACKGROUND

Patients with advanced non-small cell lung cancer (NSCLC) benefit from treatment with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) when their tumor harbors an activating EGFR mutation. As the majority of NSCLC patients present with advanced disease, cytology and small biopsy specimens are frequently the only tissue available for mutation testing, but can pose challenges due to low tumor content. We aim to better define the suitability of these specimens for mutation testing.

METHODS

NSCLC cases referred to our institution for mutation testing over a 15-month period were retrospectively reviewed. Specimens were tested for mutations including EGFR, KRAS, and BRAF, using a multiplex PCR assay (OncoCarta Panel v1.0) and analyzed on the Agena Bioscience MassARRAY platform.

RESULTS

A total of 146 specimens were tested, comprising 53 (36.3%) resection specimens (including 28 lung resection specimens), 55 (37.7%) small biopsy specimens and 38 (26%) cytology specimens. Of 142 cases with sufficient DNA for mutation testing, EGFR mutations were detected in 31 specimens (21.8%), KRAS mutations in 31 specimens (21.8%) and BRAF mutations in three specimens (2.1%). There was no significant difference in the EGFR mutation rate between lung resection (10 of 28 cases; 35.7%), small biopsy (9 of 53 cases; 17%), and cytology specimens (8 of 36 cases; 22.2%).

CONCLUSIONS

Our results support the utility of small biopsy and cytology specimens for mutation testing. Careful evaluation of the adequacy of small specimens is required to minimize the risk of false negative or positive results.

Known and putative mechanisms of resistance to EGFR targeted therapies in NSCLC patients with EGFR mutations-a review

Lung cancer is the leading cause of cancer related deaths in Canada with non-small cell lung cancer (NSCLC) being the predominant form of the disease. Tumor characterization can identify cancer-driving mutations as treatment targets. One of the most successful examples of cancer targeted therapy is inhibition of mutated epidermal growth factor receptor (EGFR), which occurs in ~10-30% of NSCLC patients. While this treatment has benefited many patients with activating EGFR mutations, almost all who initially benefited will eventually acquire resistance. Approximately 50% of cases of acquired resistance (AR) are due to a secondary T790M mutation in exon 20 of the EGFR gene; however, many of the remaining mechanisms of resistance are still unknown. Much work has been done to elucidate the remaining mechanisms of resistance. This review aims to highlight both the mechanisms of resistance that have already been identified in patients and potential novel mechanisms identified in preclinical models which have yet to be validated in the patient settings.

Efficacy of bronchoscopic biopsy for the detection of epidermal growth factor receptor mutations and anaplastic lymphoma kinase gene rearrangement in lung adenocarcinoma

Background

To explore the efficacy of bronchoscopic biopsy for the detection of epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) gene rearrangement in lung adenocarcinoma.

Methods

All patients with bronchoscopic biopsy-proven lung adenocarcinoma at the Peking Union Medical College Hospital from January 2009 to November 2011 were enrolled. Scorpion amplification refractory mutation system (ARMS) was used to detect EGFR gene mutations and fluorescence in situ hybridization (FISH) to detect ALK rearrangement. The correlation of immunohistochemistry (IHC) results with standard methods for EGFR mutation status and ALK rearrangement were checked.

Results

Bronchoscopic specimens were successfully used to detect EGFR mutation and ALK rearrangement with success rates of 85.2% and 71.3%, respectively, in non-small cell lung cancer patients. EGFR analysis by ARMS yielded a positive result in 35.8% (33/92) and positive ALK rearrangement was detected by FISH in 7.8% (6/77) of cases. It was more likely to be unsuccessful in patients with tumor cells less than 100/high power field and the ratio tumor numbers in 0–10%. In EGFR-IHC, the sensitivity and specificity of E746-A750 deletions were 73.3% (11/15) and 93.3% (70/75), respectively, and those of L858R were 93.3% (14/15) and 93.2% (69/74), respectively. In ALK-IHC, the sensitivity and specificity were 50% (3/6) and 100% (71/71), respectively.

Conclusions

Small bronchoscopic specimens could achieve higher successful detection rates via EGFR mutation and ALK gene rearrangement.

Tumour tissue sampling for lung cancer management in the era of personalised therapy: what is good enough for molecular testing?

In the era of personalised cancer therapy, the demand for molecular profiling of the patient's tumour is steadily increasing. In advanced nonsmall cell lung cancer (NSCLC) patients, testing for epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) gene rearrangements has become an essential component of clinical practice to select patients who are most likely to benefit from EGFR and ALK tyrosine kinase inhibitors, respectively. Furthermore, obtaining tissue specimens from recurrent or metastatic tumours or from patients who develop resistance to initial effective therapies are essential for our understanding of the molecular basis of tumour progression and development of drug resistance. Therefore, the sampling of tumour tissue that is representative and is adequate in quantity and quality for pathological diagnosis and genomic profiling is crucial. In this review, we will discuss factors that should be considered in obtaining and processing biopsy specimens to enable routine molecular analysis in NSCLC patients.