Increase EGFR Mutations Detection Rate in Lung Adenocarcinoma by Real-Time PCR Screening Followed by Direct Sequencing

Detection of EGFR and KRAS gene mutations using suspension liquid-based cytology specimens in metastatic lung adenocarcinoma

Background

The detection of EGFR and KRAS mutations of metastatic lung adenocarcinoma using liquid-based cytology suspension routine specimens from fine-needle aspiration remains controversial.

Results

The DNA of all specimens was extracted and real time PCR was performed successfully. The rate of EGFR and KARS mutations was 37.7% (58/154) and 5.8% (9/154), respectively. EGFR mutation rate was significantly higher in females than that in males (47.8% vs. 29.4%, P = 0.019). There were no significant differences among different age groups or different tumor sites. These results of EGFR and KRAS mutations using LBC specimens were consistant with the tissue samples. In 30 patients treated with tyrosine kinase inhibitors, complete response, partial response, stable disease and progress disease was observed in 2, 10, 13 and 5 patients, respectively.

Conclusions

Liquid-based cytology specimen is reliable and can be an alternative source for the detection of EGFR and KRAS mutations.

Methods

154 fine-needle aspiration cytologic samples were obtained from patients with metastatic lung adenocarcinoma. The specimens included 21 cases of mediastinal lymph node 123 cases of neck nodules and 10 cases of subcutaneous nodules. After the diagnosis and count of tumor cells performed by cytopathologists, liquid-based cytology specimens with sufficient tumor cells were used for EGFR and KRAS testing using real-time PCR.

Phenotype-genotype correlation in multiple primary lung cancer patients in China

Due to recent advances in high-resolution detection technology, multiple primary lung cancer (MPLC) is becoming an increasingly common diagnosis. However, the genotype-phenotype correlations in MPLC patients have not yet been assessed. In this study, we analyzed the clinical and pathological data for 129 consecutive MPLC patients who received curative surgery at the Tongji University Shanghai Pulmonary Hospital, China. We have screened 129 patients in the present study and found mutations in EGFR, BRAF, ROS1 and KRAS genes, as well as the rearrangement of the EML4-ALK gene in 113 patients. The mean patient age was 59.9 (25-78) years old and 41 patients were males (31.8%). Among the total patients, 123 (95.4%) had two primary lesions, 5 (3.9%) had three primary lesions, and 1 (0.8%) had four primary lesions. In 38.8% of the patients, all lesions were located on only one side of the body. Most of the detected mutations (98 patients) were in the EGFR gene. The patients exhibited significant differences in the EGFR mutation, age at diagnosis, and foci location.

Impact of EGFR mutation detection methods on the efficacy of erlotinib in patients with advanced EGFR-wild type lung adenocarcinoma

INTRODUCTION

Methods used for epidermal growth factor receptor (EGFR) mutation testing vary widely. The impact of detection methods on the rates of response to EGFR-tyrosine kinase inhibitors (TKIs) in EGFR-wild type (wt) lung adenocarcinoma patients is unknown.

METHODS

We recruited the Group-I patients to evaluate the efficacy of erlotinib in patients with EGFR-wt lung adenocarcinoma by either direct sequencing (DS) or mutant type-specific sensitive (MtS) methods in six medical centers in Taiwan. Cross recheck of EGFR mutations was performed in patients who achieved objective response to erlotinib and had adequate specimens. The independent Group-II lung adenocarcinoma patients whose EGFR mutation status determined by DS were recruited to evaluate the potential limitations of three MtS methods.

RESULTS

In Group-I analysis, 38 of 261 EGFR-wt patients (14.6%) achieved partial response to erlotinib treatment. Nineteen patients (50.0%) had adequate specimens for cross recheck of EGFR mutations and 10 of them (52.6%) had changes in EGFR mutation status, 5 in 10 by DS and 5 in 9 by MtS methods originally. In Group-II analysis, 598 of 996 lung adenocarcinoma patients (60.0%) had detectable EGFR mutations. The accuracy rates of the three MtS methods, MALDI-TOF MS, Scorpions ARMS and Cobas, were 87.8%, 86.8% and 85.8%, respectively.

CONCLUSIONS

A significant portion of the erlotinib responses in EGFR-wt lung adenocarcinoma patients were related to the limitations of detection methods, not only DS but also MtS methods with similar percentages. Prospective studies are needed to define the proper strategy for EGFR mutation testing.