High concordance of EGFR mutation status between sputum and corresponding tissue specimens of late-stage lung cancers using amplification refractory mutation system-PCR.

BACKGROUND:To gain sufficient tumor tissue for EGFR mutations analysis is of prime clinical importance. Therefore, the objective of present study was to assess whether sputum is suitable for EGFR testing and to assess the consistency between sputum and tissue specimens. METHODS:This analysis included 37 paired sputum and tissue specimens obtained from late-stage lung cancer patients followed by EGFR analysis using the ARSM-PCR method, and 11 sputum specimens of COPD were added as negative control. RESULTS:35 out of 37 (94.6%) patients with lung cancer were found to have tumor cells in the sputum specimen using the LCT method and extracted adequate DNA for EGFR testing. In contrast, only five out of 11 cases of COPD (45.5%) were isolated with sufficient DNA (P<0.001). Among sputum testing, higher EGFR mutation was significantly associated with NCSLC and ADC (40%, 10/25), stage IV (45.5%), and non-smoking status (43.8%). Compared with corresponding tissue specimens, the accuracy, specificity, and sensitivity of EGFR mutation analysis in sputum specimens were demonstrated as 97.1%, 96%, and 90.9%, respectively. Interestingly, a significantly high frequency of L858R in exon 21 was found (P<0.001) in all types of EGFR mutants both on sputum and tissue specimens. CONCLUSIONS:The findings of the current study suggest a high concordance between sputum and tissue specimens, reflecting the important potential of sputum specimens for EGFR mutant detection in patients with late-stage lung cancer using the ARSM-PCR method.