Elsevier

Journal of Thoracic Oncology

Volume 3, Issue 11, November 2008, Pages 1224-1235
Journal of Thoracic Oncology

Original Article
A Sensitive Method for Detecting EGFR Mutations in Non-small Cell Lung Cancer Samples with Few Tumor Cells

https://doi.org/10.1097/JTO.0b013e318189f579Get rights and content
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Background

Detection of epidermal growth factor receptor (EGFR) mutations in advanced non-small cell lung cancer (NSCLC) patients has relied on DNA purification from biopsies, amplification, and sequencing. However, the number of tumor cells in a sample is often insufficient for EGFR assessment.

Methods

We prospectively screened 1380 NSCLC patients for EGFR mutations but found that 268 were not evaluable because of insufficient tumor tissue. We therefore developed and validated a method of detecting EGFR mutations in these samples. Tumor cells were microdissected into polymerase chain reaction buffer and amplified. EGFR mutations were detected by length analysis of fluorescently labeled polymerase chain reaction products and TaqMan assay.

Results

We determined EGFR status in 217 (81%) of the 268 primary NSCLC samples not evaluable in our original study—fresh and paraffin-embedded with less than 150 cells. Exon 19 deletions were detected in 11.5% of patients and exon 21 L858R mutations in 5.5%. In addition, the exon 20 T790M mutation was detected in 6 of 15 (40%) patients at the time of progression to erlotinib. The primary, sensitive mutation was present in all tumor cells, whereas the T790M mutation was absent in some groups.

Conclusions

The method presented here eliminates the need for DNA purification and allows for detection of EGFR mutations in samples containing as few as eight cancer cells.

Key Words

Cytologic samples
EGFR mutations
erlotinib
Non-small cell lung cancer
T790M

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Disclosure: The authors declare no conflicts of interest.

The first four authors contributed equally to the article.