Yao ZH, et al. - One hundred and seventy-one subjects who were diagnosed with non–small-cell lung cancer (NSCLC) from 2011 through 2017 and who also had positive hepatitis B surface antigen (HBsAg) were recruited in a study by the researchers in order to determine the incidence of hepatitis B virus (HBV) reactivation during the treatment by epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) in NSCLC subjects. The median span of EGFR TKI treatment was observed to be 10.5 months. During EGFR TKI treatment, 16 subjects met the criteria of HBV reactivation, with an annual incidence of 7.86%. In 6 subjects, HBV reactivation occurred during erlotinib treatment, followed by 5,3 and 2 patients with gefitinib treatments, with osimertinib treatment and with afatinib treatment, respectively. For HBV reactivation, no independent risk factor was recognized. Hence, during the treatment period, NSCLC subjects who receive EGFR TKI treatment may have a clinically significant risk of HBV reactivation. Moreover, for NSCLC cases with positive HBsAg, monitoring liver function, HBV viral load and serology of HBV (ie, HBeAg and anti-HBc) during EGFR TKI therapy is suggested.