Abstract
Objective. This study aims to clarify whether there are epidermal growth factor receptor (EGFR) mutation false-negative results among non-small cell lung cancer (NSCLC) patients without an EGFR mutation who exhibit a good response to erlotinib treatment. Methods. We analyzed NSCLC patients without an EGFR mutation who received erlotinib treatment at NTT Medical Center Tokyo. The EGFR mutation status was reexamined using the modified PNA-LNA PCR clamp method. The efficacy of erlotinib and the prognosis were re-estimated. Results. Of the 20 patients, seven were male and 13 were female, with a median age of 64 years (range: 44 to 77). The histological subtype was adenocarcinoma in 18 patients and NSCLC NOS in two patients. Thirteen patients had c-Stage of IV disease, two patients had IIIB disease and five developed postoperative recurrence. The performance status of the patients was PS 0-1: 16, PS 2-: 4, and the median number of erlotinib treatment days was 144. The median progression-free survival and overall survival since erlotinib treatment were 127 days and 357 days, respectively. Of the 20 patients enrolled, six showed a partial response (PR), five exhibited stable disease (SD) and nine exhibited progressive disease (PD), giving a response rate of 30.0%. Of the 16 patients in whom the EGFR mutation status was reanalyze using the modified PNA-LNA PCR clamp method, eight patients were found to have an EGFR mutation. The response rate of the eight patients without an EGFR mutation was 0%, whereas that of the eight patients with an EGFR mutation was 62.5%. Among the patients without an EGFR mutation, the median progression-free survival and overall survival since erlotinib treatment were 47 days and 218 days, respectively. Among the patients with an EGFR mutation, the median progression-free survival and overall survival since erlotinib treatment were 387 days and 836 days, respectively. Conclusions. There are false-negative results regarding the EGFR mutation status determined using the PNA-LNA PCR clamp method.
