Introduction

Currently, locally recurrent or metastatic breast cancer is incurable and considered a chronic disease. Although pallitative endocrine therapies and chemotherapies cause tumor remissions, they fail to considerably prolong survival. However, when patients, suffering from HER2-positive locally recurrent or metastatic breast cancer, were treated with trastuzumab, impressive improvements of overall survival were reported. Of special interest are long-term tumor remissions under trastuzumab therapy, which have not frequently been reported for other regimens. The HER-OS database for long-term survivors was set up to collect data from patients with long-time tumor remission under trastuzumab therapy and to analyze factors, which are correlated with these long-term remissions.

Methods

This is the first interim analysis of datasets from 220 patients in 71 german centers, registered in HER-OS. Eligible were patients with HER2- positive locally recurrent or metastatic breast cancer, who had remissions (complete or partial response) for at least 2 years under trastuzumab therapy. Retrospective as well as partial retro-/prospective documentation was allowed. From December 2006 until April 2010 220 patients were sufficiently documented to be analyzed for demographic data, tumor biology, adjuvant and palliative treatments (surgery, radiation therapy, endocrine therapy, chemotherapy) as well as time to progression under trastuzumab therapy and overall survival.

Results

Patients had a median age of 53.2 years and 72.3% were younger than 60 years at time of first diagnosis. 10.0% of patients had primary distant metastasis at time of first diagnosis and in general patients were in good physical condition (51.8 % with ECOG performance status 0). During breast cancer pretreatment in the adjuvant setting, 86.4% of the patients had primary surgery, 63.2% received adjuvant chemotherapy and 40.9% received adjuvant endocrine therapy. In the metastatic situation 5.5% of patients had surgery, 51.8% received chemotherapy and 32.7% endocrine therapy.

The patients had a median age of 58.5 years at start of trastuzumab application and the median duration of trastuzumab treatment was 47.1 months. Secondary CNS metastases were reported for 13.2% of patients and occurred after a median trastuzumab treatment duration of 26.9 months.

As only 86 of 220 patients in the population had progressive disease at time of analysis, the median time to progression was not reached yet. Still, quartile estimates indicate a median time to progression of 58.5 months [95%-CI (47.8-114.5)]. Conclusion

220 patients with tumor remissions for at least 24 months under trastuzumab therapy were evaluated in the first interim analysis of the HER-OS database. The population was in general of young age and in a good physical condition. At the time of analysis secondary CNS metastases were reported only in 13.2% of the patients. The estimated median time to progression is 58.5 months and will be confirmed in the future. In conclusion, these data indicate that treatment with trastuzumab contributes to manage HER2-positive locally recurrent or metastatic breast cancer as chronic disease.

Updated results will be presented at the meeting.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-14-19.