A significantly higher incidence of EGFR mutations was observed in bronchioloalveolar carcinomas (28%, p=0.019) and in adenocarcinomas (21%, p=0.024) than in large cell carcinomas, mixed adenocarcinomas, and NOS (4%).
Although only adenocarcinomas or NSCLC-not otherwise specified are recommended for EGFR mutation testing, EGFR mutations in 11% of the large cell carcinomas and 4% of the squamous cell carcinomas were observed.
Moreover, UbcH10 expression is significantly higher in squamous cell and large cell carcinomas than in adenocarcinomas, and directly and inversely correlated with the mutational status of p53 and EGFR, respectively.
Of the 697 NSCLC patients, 235 (33.7%) patients had tyrosine kinase inhibitor (TKIs) sensitive EGFR mutations in 41 (14.5%) of the 282 squamous carcinomas, 155 (52.9%) of the 293 adenocarcinomas, 34 (39.5%) of the 86 adenosquamous carcinomas, one (9.1%) of the 11 large-cell carcinomas, 2 (11.1%) of the 18 sarcomatoid carcinomas, and 2 (28.6%) of the 7 mucoepidermoid carcinomas.
We analyzed 147 NSCLC tissues [70 adenocarcinomas (AD), 62 squamous cell carcinomas (SQ), 12 large cell carcinomas (LC), and three adenosquamous carcinomas] that had not been exposed to the TKI therapies, and found 12 (8.2%; 12/147) EGFRT790M mutation in eight AD (11.4%), three SQ (4.8%), and one LC (8.3%) by the PNA-clamping PCR.
EGFR positivity was seen most frequently in squamous cell carcinomas (77%), followed by TRU-type adenocarcinomas (63%), large cell carcinomas (23%), and non-TRU-type adenocarcinomas (12%).
In invasive tumors, EGFR are expressed in 50-90%, and mostly in squamous cell carcinomas, but also in adenocarcinomas and large cell carcinomas, while HER2 is less frequently expressed (20-30%) and mostly expressed in adenocarcinomas.