registHER: Baseline characteristics of a cohort of HER2-positive metastatic breast cancer (MBC) patients
20095 Background: HER2 is amplified in 25% of breast cancers and is associated with poor survival. registHER captures the natural history, treatment patterns and outcomes in 1000 newly-diagnosed HER2-positive MBC patients (pts) throughout the U.S. This observational study recruits pts in both academic and community centers. Methods: This ongoing prospective cohort study collects clinical, pathologic and treatment data at enrollment, quarterly until death, loss to follow-up or 3 years after the last enrollment. We describe baseline pt and clinical characteristics in registHER compared with HER2-positive MBC pts in the phase III pivotal trial (Slamon DJ, et al. N Engl J Med. 2001;344:783–792). Results: Between December 2003 and September 2005, 813 eligible pts were enrolled at 280 study sites. Most pts were seen at community-based (76%) vs academic (18%) clinics; a few pts did not fall into either category (6%). A comparison of baseline characteristics is shown below. Conclusions: registHER pts tended to have a shorter disease-free interval and more estrogen receptor positive disease than pts in the pivotal trial. Reasons for these differences could reflect trial referral and/or diagnostic testing differences. Fewer registHER patients were white, but other characteristics were similar between the two groups. These findings support the hypothesis that observational studies describe a broad patient population which may not exactly duplicate clinical trials. Within registHER, there was some variation between academic vs community clinics (eg. nodal status and adjuvant therapy). Treatment pattern analyses are ongoing. [Table: see text] [Table: see text]