PIK3CA and small cell lung carcinoma: The results showed the occurrence of the following mutations: 18.7% (25/134) had TP53 mutations; 17.8% (24/134) had MET mutations; 11.2% (15/134) had small cell lung cancer histological pathology transformation; 5.6% (8/134) had the C797S mutation; 5.6% (8/134) had the KRAS mutation; 5.6% (8/134) had the PIK3CA mutation; 3.7% (5/134) had the BRAF mutation; 2.8% (4/134) had the CCNE1 amplification; 2.8% (4/134) had the CDK6 amplification; 2.8% (4/134) had the ratio of CCDC6-RET fusion; and the ratio of HER2 amplification occurred in 1.9% (3/134).