First-line treatment with lapatinib plus paclitaxel versus paclitaxel alone for patients with HER2+ metastatic breast cancer (MBC): Quality-of-life (QOL) analysis using repeated measures and pattern mixture models

1049 Background: A phase III randomized, multicenter, double-blind, placebo-controlled study compared first-line therapy with lapatinib and paclitaxel (L+P) versus paclitaxel alone (P) for MBC. In a sub-group analysis of HER2+ patients, time to tumor progression for L+P was significantly improved, with an emerging trend for survival benefit. This analysis models the QOL data in the subset of the randomized ITT population that overexpressed HER2 (FISH+ or IHC3+). Methods: QOL was assessed using the Functional Assessment of Cancer Therapy-Breast (FACT-B) questionnaire. Outcome measures included FACT-B total score, trial outcome index (TOI) score and breast cancer subscale (BCS). Higher scores represent better QOL. Patients completed the FACT-B at the screening visit, week 9, every 12 weeks thereafter, and at discontinuation of therapy. The assessment at discontinuation was applied to the next scheduled visit for analyses. Changes from baseline were analyzed using repeated measures models with baseline score...