Abstract P4-12-04: Initial treatment and survival among elderly breast cancer patients by receipt of human epidermal growth factor receptor 2-targeted therapy: An analysis of US national data 2006-2009

Abstract

Abstract BACKGROUND: There are few studies of initial treatment and survival among elderly, newly diagnosed breast cancer (BC) patients stratified by receipt of human epidermal growth factor receptor 2- (HER2-) targeted therapy. METHODS: Using linked Surveillance, Epidemiology, and End Results (SEER) and Medicare claims and enrollment data from 2006-2009, women aged 65+ years with an incident diagnosis of BC (index date) in 2007 and no prior history of any other cancer were identified and followed to evaluate initial treatment and survival. Study patients were required to have continuous enrollment from 1 year before index (baseline period) through the end of the data window, disenrollment or death, whichever came first. Patients were classified as having received HER2-targeted therapy if they had any claim indicating trastuzumab or lapatinib following diagnosis. Demographics, initial treatment (within 4 months of diagnosis), and survival (proportion of patients who died during the study period) were evaluated by receipt of HER2-targeted therapy (and by age and stage among those who received HER2-targeted therapy). Kaplan-Meier (KM) survival curves and survival at 36 months were estimated by stage. Treatment included surgery, radiation, chemotherapy, biologic, and hormone therapy, and was evaluated among patients with > 2 months of follow-up. RESULTS: Among 11,238 female BC patients, 510 received HER2-targeted therapy (99.8% trastuzumab, 2.5% lapatinib) and 10,728 did not. Those who received HER2-targeted therapy were slightly younger at diagnosis (mean age 73 vs. 76, P<0.01) and less likely to have positive estrogen receptor (ER+; 52.7 vs. 85.1%, P<0.01) and progesterone receptor (PR+; 37.8 vs. 72.6%, P<0.01) status. They were also more likely to be diagnosed at later stages (Stage III: 23.3 vs. 7.4%; Stage IV: 10.6 vs. 4.9%; P<0.01). Patients with HER2-targeted therapy were less likely to receive surgery (87.5 vs. 91.9%; P = 0.06), radiation (39.0 vs. 43.2%; P<0.01), or hormone therapy (6.9 vs. 16.8%, P<0.01), but more likely to receive chemotherapy (69.8 vs. 12.6%, P<0.01). Mortality was similar between the two groups (15.3% for HER2-targeted therapy vs. 16.1% for non HER2-targeted therapy, P = 0.71). Among patients receiving HER2-targeted therapy, increased age (P<0.01) and later stage (P<0.01) were associated with higher mortality. Older patients were more likely to receive hormone therapy (P = 0.02) and less likely to receive chemotherapy (P = 0.02) and surgery (P = 0.08). Patients in later stages were less likely to receive surgery (P<0.01) or radiation (P<0.01) and more likely to receive chemotherapy (P = 0.01) or hormone therapy (P = 0.05). CONCLUSIONS: Elderly, newly diagnosed BC patients who received HER2-targeted therapy were younger than those who did not received HER2-targeted therapy. Initial treatment patterns varied between the two groups, but survival outcomes were similar. Among patients in the HER2-targeted therapy group, treatment characteristics also differed by disease stage and age. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-12-04.