Abstract P3-13-11: Unexpected large treatment and outcome variations in metastatic breast cancer: Results of a hormone receptor positive cohort study in the Netherlands
Authors: Tjan-Heijnen VCG , Lobbezoo DJA , van Kampen RJW , Voogd AC , Dercksen M , van den Berkmortel F , Smilde TJ , van de Wouw AJ , Peters FPJ , van Riel JMGH , Peters NAJB , de Boer M , Peer PGM 
Published: August 2014

Introduction

Treatment of patients with metastatic breast cancer (MBC) generally has a palliative intent. The systemic treatment approach is based on hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) status. However, with a variety of available agents and major changes in adjuvant breast cancer treatment, treatment decisions in MBC are complex. The objective of this study was to present treatment patterns of HR positive metastatic breast cancer patients, categorized by HER2 status.

Patients and methods

All patients diagnosed with HR positive MBC between 2007 and 2009 (irrespective of date of primary diagnosis) in eight participating hospitals in the South-East part of the Netherlands were included and all medical charts were reviewed. Patient and tumor characteristics as well as treatments and outcomes were collected. Survival was estimated using the Kaplan-Meier method.

Results

A total of 611 patients had HR positive MBC; 529 of these (86.6%) had a negative HER2 status. Median survival after diagnosis of distant metastases was 22.1 months for the HR+/HER2-subtype and 32.9 months for the HR+/HER2+ subtype.

In the HR+/HER2- subgroup 7% of patients did not receive any palliative systemic treatment and in the HR+/HER2+ subgroup 8.5% of patients did not receive any palliative systemic treatment.

In the HR+/HER2- subgroup, first given palliative systemic treatment was chemotherapy in 22% and endocrine therapy in 71% of patients. Of the patients starting with chemotherapy, 15% had bone metastases only, 37% had visceral metastases and 39% had multiple metastatic sites compared to 49%, 20% and 25% respectively for those starting with endocrine treatment. Of the patients starting with chemotherapy, 38% had progressive disease during or after this line of treatment and 62% had either response or stable disease.

In the HR+/HER2+ subgroup, 59.8% of patients received chemotherapy as first palliative systemic treatment (in two thirds of these patients targeted therapy was added to the chemotherapy) and 31.7% received endocrine therapy with or without trastuzumab. Of the patients starting with chemotherapy (+/- targeted therapy) 20% had bone metastases only, 39% visceral metastases and 37% had multiple metastatic sites versus respectively 23%, 31% and 35% for the patients starting with endocrine therapy. Of the patients starting with chemotherapy (+/- targeted therapy), 17% had progressive disease during or after this line of treatment and 83% had either response or stable disease.

Conclusion

A considerable proportion of HR+ MBC patients received chemotherapy as first given treatment despite HR positive status and presence of bone metastases only or limited visceral metastases, which is more than expected based on current treatment guidelines. Daily-practice monitoring of MBC, as we have reported here, may improve future treatment decision-making.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-13-11.