Mitra D, Kurosky S, Kaye JA, Harbeck N. Treatment patterns and clinical outcomes in ER+/HER2- metastatic breast cancer in German real world settings. Poster presented at the ECCO2017: European Cancer Congress; January 28, 2017. Amsterdam, The Netherlands. [abstract] Eur J Cancer. 2017 Feb; 72(Suppl 1):S141. doi: 10.1016/S0959-8049(17)30538-5.

BACKGROUND: To examine treatment patterns and clinical outcomes among postmenopausal patients with estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2−) metastatic breast cancer (MBC) in German real-world settings.

MATERIALS AND METHODS: A retrospective review of medical records was conducted in Germany as part of a larger multi-country study. Records were abstracted for ER+/ HER2− MBC patients who received at least two lines of therapy for metastatic disease between January 1, 2008, and March 1, 2014. Patient and clinical characteristics, treatment patterns, and time to progression (TTP) by treatment line were assessed.

RESULTS: Medical records were reviewed for 251 patients by 58 physicians across Germany. Patients’ mean age was 63 years at metastatic diagnosis, and over 96% were white. Bone was the most common site of metastasis (69%), followed by liver (51%), and lung/ pleura (47%); Majority had visceral disease (73%) and were ECOG performance status 0 or 1 (66%). In the 1st line MBC setting, 50% of patients received endocrine therapy (ET) alone, 27% received chemotherapy (CT) alone, and the remainder received both (in combination [18%] or CT followed by ET [6%]). Anastrazole (24%), letrozole (22%) and paclitaxel (19%) were the 3 most common 1st line agents. Nearly 80% of patients progressed on 1st line with a median TTP of 8.2 months (9 months for those on ET alone; 5.4 months for those receiving CT alone). Among those on ET alone, 84% discontinued treatment due to disease progression, of which nearly 100% due to endocrine therapy resistance as reported by the physician. In the 2nd line, 51% received ET alone, 35% received CT alone, 10% received combination ET and CT, while 4% received CT followed by ET. The most common 2nd line agents were exemestane (20%), fulvestrant (18%), and paclitaxel (14%). Progression on 2nd line treatment was seen in 87% of patients with a median TTP of 6.0 months (7.3 months for ET alone, 4 months for CT alone). 73% of patients on ET alone discontinued due to disease progression, of which 96% were attributed to endocrine resistance by the physicians.

In ER+ HER2− MBC, more than 50% of patients received ET alone in both first and second line of therapy. Median TTP on ET is well below 1 year (9 months for first line, 7 months for second line), with TTP for those on CT alone under 6 months for both first and second line. Note that a comparison of outcomes between treatment groups (ET vs chemotherapy) may be confounded by severity in an observational study (i.e., “channeling” of patients with a worse prognosis to receive chemotherapy rather than ET). Endocrine treatment discontinuation was attributed to endocrine resistance by physicians in the majority of patients.

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