Efficacy of first-line erlotinib in non-small cell lung cancer patients undergoing dose reduction and those with a low body surface area: A population-based observational study by the Ibaraki Thoracic Integrative (POSITIVE) Research Group.

The aim of the present study was to evaluate the efficacy of erlotinib, one of the 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, disease control rate, time to treatment failure and overall survival, were evaluated in patients prescribed first-line erlotinib for EGFR mutated non-small cell lung cancer patients between April 2012 and March 2015. A total of 22 patients received first-line erlotinib during the study period. A dose reduction of erlotinib for the reason of low BSA and poor performance status occurred in 14 (63.6%) of the patients: 6 (27.3%) had initial dose reduction, 6 (27.3%) had dose reduction in their clinical courses, and 2 (9.1%) had both. Dose reduction of erlotinib with the initial dose of erlotinib/BSA was >80 mg/m2, and longest-term prescribed dose of erlotinib/BSA was >50 mg/m2, which may have no association with a survival disadvantage. Dose-reduction estimation studies for TKIs may be crucial, particularly for patients with a low BSA. Future prospective studies and confirmation of these results in population-based retrospective ones investigating the incidence of dose reduction in patients with AEs and those with low BSA may be required for the efficient use of erlotinib in common clinical practice.