Objective  To investigate the co-mutation of PIK3CA gene and other oncogenes in non-small cell lung cancer(NSCLC) patients in China.

  Methods  Data were obtained from the patients with pathologically confirmed NSCLC and receiving gene mutation testing in 25 hospitals in China between September 2009 and April 2012. Nine genetic loci were tested and analyzed, including PIK3CA E9, PIK3CA E20, KRAS E2, KRAS E3, BRAF, and EGFR(E18, E19, E20, E21).

  Results  A total of 5125 patients were included in this study, of which 161(3.14%) had multiple mutations, including 77 with mutations in PIK3CA, 50 in E9 and the other 27 in E20.The other oncogene mutations coexisting with PIK3CA mutations included KRAS E2 (11 cases), KRAS E3 (1 case), BRAF (2 cases), EGFR E18 (4 cases), EGFR E20 (5 cases), EGFR E21(28 cases), and EGFR E19 deletions (37 cases).Among mutations in PIK3CA, E9 was more likely than E20 to have coexisting mutations, also more likely to coexist with EGFR E21 L858R than EGFR E20; whereasamong mutations in PIK3CA E20, H1047R was more common than H1047L.Mutations in KRAS coexisting with PIK3CA appeared mostly in E2 G12 locus. Mutations in BRAF V600E were also inclined to coexist with PIK3CA.

  Conclusions  PIK3CA might tend to appear concurrently with other oncogene mutations in Chinese NSCLC patients, while mutations in PIK3CA E9 and E20 are mutually exclusive. Further research is need to reveal the significance of coexistence of PIK3CA and other oncogene mutations in NSCLC and its impact on patient outcome.