a trend toward significanceP = 0.01
An interaction test revealed significant results for OS and showed a trend toward significance for PFS between primary tumor sidedness and the treatment arms in the respective study (OS: P = 0.01; PFS: P < 0.01); additionally, a significant interaction was observed between anti-EGFR and non-anti-EGFR treatment and PTS for both OS ( P < 0.010) and PFS ( P = 0.05).