Conclusion
Our results indicate that PIK3CA mutations may confer a survival advantage in early stage squamous cell lung cancers, but further work is needed to confirm this finding.
Methods
Tumour tissue was obtained from 308 consecutively operated lung cancer patients with squamous cell carcinoma in the period 2003-2013. DNA was isolated according to standard procedures, and mutation analysis was done with either the SnapShot method and/or using PIK3CA specific primers in the Cobas system. PD-L1-expression was analysed with immunohistochemistry After thorough follow-up (median 67.6 months), overall survival and time to relapse was calculated.
Results
Tumour tissue from 102 females and 206 males were analysed. 167 (54.2%) were in stage I, 96 (31.2%) in stage II and 45 (14.6%) in stage III. PIK3CA mutation was found in 35 (11.4%) patients, most frequently in exon 20. There were no differences in sex, stage or smoking behaviour between mutated and non-mutated cases. Patients with PIK3CA mutations had a significantly longer overall survival (p=0.042) and time to relapse (p=0.030) than non-mutated cases, and the difference in time to relapse was also retained in stage I-cases (p=0.044). PD-L1-expression was less frequent among mutated cases.