Women with HER2+MBC are living longer but little is known about their long-term treatment patterns and survival. We describe the demographics, treatment characteristics, and overall survival (OS) for an Australian cohort of long-term survivors with HER2+MBC.
We used Herceptin Program dispensing records to identify women surviving ≥5 years from initiation of trastuzumab for MBC. We used Kaplan-Meier methods to estimate time-on-trastuzumab (from first dispensing date until last dispensing, plus 30 days) and OS (time from first trastuzumab dispensing until death or last date alive). We defined a break of ≥90 days between trastuzumab dispensings as a separate treatment course. We used dispensing records to determine the type and duration of additional cancer treatments.
We identified 1,082 women surviving ≥5 years from first dispensing of trastuzumab: 26% of all trastuzumab-treated patients between 2001-2011. Median age (interquartile range [IQR]) at initiation was 54 years (46–63). Median time-on-trastuzumab was 4.9 years (2.3–7.4); time on chemotherapy 1.2 years (0.4 – 3.5); and time on endocrine therapy 4.8 years (1.9 – 9.6). 333 women (31%) received at least one other HER2-targeted therapy. 655 patients (61%) had >1 break in trastuzumab therapy with a median break duration of 0.9 years (0.3 – 4.3), and 317 (29%) received <2.5 years of trastuzumab during the first 5 years. Median OS was 11.6 years (7.0–not reached).
Our findings provide population-based estimates of the 5-year survival rate and median durations of therapy and OS for long-term surviving HER2+MBC patients treated with trastuzumab. With the availability of new and effective HER2-targeted therapies the number of long-term survivors is likely to increase and these data are potentially useful for treating oncologists and for policy makers from the perspective of resource use and costs.