P295 Management of breast cancer subtypes: Are we headed in the right direction?

Abstract

Goals: Identification of distinct breast cancer subtypes based on variation in expression of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (Her2) has led to a more personalized treatment approach. Since 2005, we are using adjuvant trastuzumab and also offering more aggressive chemotherapy with the incorporation of adjuvant taxanes. Our goal was to determine whether given increased systemic therapy options, the prognosis of patients with three different subtypes of breast cancer [Her2+; Her2−, ER/PR+; and triple negative (TN)] was comparable. Methods: We conducted a chart review of female patients 18 years at an academic cancer centre in Canada, who were seen by a medical oncologist between January 1, 2005 and December 31, 2006 for a new diagnosis of stage I-III invasive breast cancer. Clinical features as well as the 3and 5-year overall and relapse-free survival of the three subtypes were compared. Results: Of 870 patient reviewed, 533 met the inclusion criteria. TN patients were youngest with a mean age of 50.36 compared with 53.46 and 56.85 for the Her2+, and Her2-, ER/PR+ groups, respectively (p< 0.001). At 5 years, overall survival (OS) and relapse-free survival (RFS) were 87.9%, 96.3%, and 84.6%; and 76.0%, 88.5% and 81.0%, for Her2+, Her2-, ER/PR+ and TN, respectively. Using Her2-, ER/PR+ as a reference, TN had the worst overall survival (HR 4.21, 95%CI 1.55–11.41) and relapsefree survival (HR 1.93, 95%CI 0.92–4.06). Analysis of systemic therapy use revealed that systemic chemotherapy was most commonly used in the Her2+ group, followed by TN and Her2-, ER/PR+, with rates of use of 84%, 81% and 41%, respectively. Only 74% of Her2+ patients received trastuzumab. Conclusion: Patients with early stage breast cancer have improved outcomes with excellent 5-year OS and RFS. Despite strong evidence for adjuvant trastuzumab, there are still many patients who don’t receive this therapy and this may impact their RFS and OS. TN patients have poorer outcomes despite aggressive use of adjuvant chemotherapy. Disclosure of Interest: None Declared