Abstract P6-08-50: Clinical predictors of long-term survival in Her2-positive (HER2+) metastatic breast cancer (MBC)
Authors: Murthy Pooja , Kidwell Kelley M , Thomas Dafydd G , Griggs Jennifer J , Merajver Sofia D , Schott Anne F , Smerage Jeffrey B , Van Poznak Catherine H , Wicha Max , Hayes Daniel F , Henry N Lynn 
Published: May 2015

Introduction: Clinical observation suggests that a subset of patients with HER2+ MBC survive for prolonged periods when treated with Her2-targeting regimens. We hypothesized that we could identify clinical and pathological factors associated with prolonged survival.

Methods: An IRB approved, retrospective, single institution review of patients diagnosed with HER2+ MBC was performed. Patients treated with pertuzumab or ado-trastuzumab emtansine were not included because recent FDA approval did not permit long-term follow-up. Clinical and pathologic characteristics were abstracted from the medical record. Kaplan Meier curves were constructed to evaluate time to progression after first metastasis, and overall survival from time of first metastasis. Cox proportional hazards analysis was used to assess for factors associated with long-term survival. A p value of &lt;0.05 is statistically significant.

Results: Review identified 181 patients with HER2+ MBC. Median age was 47 (range 35-80). More than half (N=107) had hormone receptor positive disease; 21% had received adjuvant trastuzumab; and 25% had stage IV disease at diagnosis. Median overall survival from the time of MBC diagnosis was 4.2 yrs (range 0.1-15.5). Since the diagnosis of MBC, 70 (38%) survived for 5 or more yrs and 15 (8%) survived more than 10 yrs. One third (N=59) of patients had brain metastases. These patients had a median survival of 1.5 yrs (range 0-12.5 yrs) with 14% (N=8) living for more than 5 yrs following diagnosis of brain metastasis. Factors associated with decreased survival are listed in Table 1.

Factors Associated with Decreased Survival in Her2+ MBCFactorHazard Ratio (95% C.I.)P ValueAge (continuous)1.03 (1.01-1.04)0.0004Time to recurrence (continuous)0.99 (0.94-1.04)0.74Hormone receptor positive0.70 (0.49-0.99)0.042Brain metastasis1.09 (0.77-1.56)0.63Adjuvant anti-Her2 therapy0.98 (0.61-1.58)0.94Multiple (vs single) sites of disease at initial diagnosis of MBC1.66 (1.17-2.35)0.005

Conclusions: In the treatment era of trastuzumab and lapatinib, 8% of patients within this cohort with HER2+ MBC lived more than 10 yrs. Analysis of current standard clinical and pathologic characteristics are not predictive of survival duration. Identifying factors associated with prolonged survival may provide insights for individualizing treatment selection.

Citation Format: Pooja Murthy, Kelley M Kidwell, Dafydd G Thomas, Jennifer J Griggs, Sofia D Merajver, Anne F Schott, Jeffrey B Smerage, Catherine H Van Poznak, Max Wicha, Daniel F Hayes, N Lynn Henry. Clinical predictors of long-term survival in Her2-positive (HER2+) metastatic breast cancer (MBC) [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P6-08-50.