Abstract P4-09-10: Prevalence of Triple Negative Breast Cancer (TNBC) and Its Management in 3 Large Breast Cancer Centres in Australia: A Retrospective Review

Abstract

Abstract Background: Triple negative (ER, PR, HER2 negative) breast cancer (TNBC) is a recognised subtype of invasive breast cancer (BC) associated with a worse prognosis. It represents 10-15% of BC and currently there is no tailored therapy in the adjuvant or metastatic setting. Review of outcomes in BC patients (pts) treated by conventional cytotoxics, can provide some understanding as to efficacy of currently used agents and provide an indication of rates of recurrence and disease response to chemotherapy in a non-trial setting. Methods: The databases of 3 large Australian centres were examined for BC patients with TN tumours defined as: ER and PR negative on immunohistochemistry (IHC) and HER2 negative by either IHC 0 or 1+ or on ISH. Data was entered prospectively and collectively analysed for prevalence, management and outcome of pts with TNBC seen between January 1998 — December 2009. Pt and tumour characteristics were compared to those with non-TNBC. For the TNBC cohort, details on adjuvant chemotherapy given and relative dose intensity (RDI) was assessed. Disease-free survival, breast cancer event rate and systemic treatment given and response in the first-line metastatic setting will be reported. Results: Over the 12 yr period, 4902 BC pts were seen with 643 (13%) TNBC (98% operable and 2% metastatic at diagnosis). Median age was 51 years (range, 24-90) and 40% were premenopausal at diagnosis. Tumour characteristics for the entire group are shown in Table 1 and adjuvant treatment given to pts with TNBC in Table 2. With a median follow-up (mfu) of 36 months (m) (0.2-142), 184 BC events occurred in 154/643 pts (25%). First event was CBC 3.5%, local recurrence 6.7%, metastatic 16.4% (Lung 37%, Lymph nodes 34%, Bone 31%, Liver 27%, CNS 9%). The median DFS was 33m with 77% of BC events occurring within 5yrs. Of the 105 pts who died from BC, median time from metastatic diagnosis to death was 10 months (0.1 - 65). Conclusions: In 3 large oncology institutions, 13% of new pts with BC had TNBC. Despite adequate dose delivery of anthracycline/taxane/combination anthracycline-taxane adjuvant chemotherapy in 78% of these pts, 25% of pts had a BC event at mfu of 3yrs. Despite the majority of pts receiving taxane, capecitabine or anthracyclines in the first-line metastatic setting, median survival was only 10 months, with 75% of pts dying by 2 yrs from metastatic diagnosis. More effective therapies are required in both the adjuvant and metastatic setting for treatment of this aggressive subtype of BC. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-09-10.