Between 2001 and 2015 the Herceptin Program (HP) provided trastuzumab to Australians with HER2-positive MBC. We aim to characterise treatment patterns and outcomes for this whole of population cohort.
This retrospective cohort study used linked HP records, PBS and MBS claims, and fact of death data obtained from the Department of Human Services. We stratified patients into four year-of-trastuzumab-initiation groups: 1: 2001– 2002; 2: 2003–October 2006; 3: October 2006–December 2012; and 4: December 2012–31 March 2014 (data censor date). We determined total duration of trastuzumab (date of initial dispensing until 21 days after last dispensing) and duration of the first course; a break of ≥90 days between dispensings was considered a separate course. We used Kaplan-Meier methods to estimate treatment duration and overall survival (OS). We used dispensing dates of cancer medicines to determine concomitant treatments, and MBS claims for echocardiography and MUGA scans to determine frequency of cardiac monitoring.
5,631 patients received trastuzumab for MBC. Median age 56 years (IQR: 48 – 65). 11% had also received adjuvant trastuzumab. The median total duration of therapy was 13.7 months (IQR: 6.1 – 27.2). Median duration of first course of therapy increased from 8.5 months (3.4–20.8) in Group 1 to 13.8 months (5.9–29.4) in Group 3. Median OS increased from 21.8 months (9.5 – 53.6) in Group 1 to 34.4 months (15.1 – Not reached) in Group 3. 78% of patients received concomitant taxanes. Baseline cardiac assessment increased from 35% in Group 1 to 70% in Group 4. Overall, 57% had ≥1 cardiac assessment during treatment.
Similar to clinical trial estimates, duration of first course of trastuzumab and OS have increased over time. In keeping with the HP, most patients started trastuzumab with taxane chemotherapy. Pre-treatment cardiac assessment improved over time but was not universal.