Efficacy of tyrosine kinase inhibitors in non-small-cell lung cancer patients undergoing dose reduction and those with a low body surface area.

The objective of this study was to evaluate the efficacy of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) in patients undergoing dose reduction and in those with a low body surface area (BSA). The association between dose reduction, low BSA and efficacy, including response rate (RR), disease control rate (DCR), progression-free survival (PFS) and overall survival (OS), were evaluated in patients prescribed TKIs between September, 2002 and May, 2013. A total of 282 patients received EGFR-TKIs during the study period, 53 (18.8%) of whom underwent a dose reduction (21.4 and 31.6% of the patients with a BSA of <1.5 and <1.25 m2, respectively). Eleven (20.8%) of these 53 patients had a dose reduction due to adverse events (AEs) >grade 3. In either gefitinib or erlotinib treatment, the RR, DCR, PFS and OS in EGFR-mutated patients with a BSA of <1.5 m2 were not different from those in patients with a BSA of >1.5 m2. In addition, there were no differences in these parameters between patients with and those without a dose reduction of TKIs. The dose of TKIs in patients with AEs and in those with low BSA should be determined with caution. To confirm the equal efficacy of TKIs in patients undergoing a dose reduction, prospective observational studies with less patient heterogeneity are required.