Dataset Information

Treatment patterns and survival in HER2-positive early breast cancer: a whole-of-population Australian cohort study (2007-2016).

ABSTRACT:

Background

Randomised clinical trials (RCTs) demonstrate that trastuzumab improves survival in patients with human epidermal growth factor 2-positive early breast cancer (HER2 + EBC), but real-world patients and clinical practice often differ from RCTs. We examine real-world treatment patterns and outcomes associated with trastuzumab for HER2 + EBC.

Methods

We identified all Australians dispensed trastuzumab for HER2 + EBC between 1/1/2007 and 30/6/2016. We estimated the proportion of patients completing 12 months of treatment (defined as ≥350 days of exposure within 540 days of initiation). We estimated overall survival (OS) and recurrence-free survival (RFS) by using trastuzumab dispensing for metastatic breast cancer as a surrogate for recurrence.

Results

Our study included 14,644 patients. Among patients with ≥540 days of follow-up (n = 11,903), 67.4% completed 12 months of trastuzumab. OS rates at 5 and 9 years were 92.7 and 87.9%, and RFS rates at 5 and 9 years were 86.8 and 81.4%, respectively. Patients who completed 12 months of trastuzumab had a 9-year OS rate of 90.2% compared with 86.2% among patients receiving <12 months of therapy (adjusted HR 0.71, 95% CI 0.62-0.81).

Conclusions

Real-world HER2 + EBC patients are less likely to complete 12 months of trastuzumab than some clinical trial counterparts but have survival outcomes comparable to those reported in landmark RCTs.

SUBMITTER: Tang M

PROVIDER: S-EPMC6889396 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Background:In premenopausal patients with human epidermal growth factor receptor 2 (HER2)-positive early breast cancer, the gonadotoxicity of trastuzumab and lapatinib remains largely uncertain, and the prognostic effect of treatment-related amenorrhea (TRA) is unknown. Methods:In the Adjuvant Lapatinib and/or Trastuzumab Treatment Optimization (BIG 2-06) phase III trial, HER2-positive early breast cancer patients were randomized (1:1:1:1) to receive one year of trastuzumab, lapatinib, their sequence, or their combination. As per study protocol, menopausal status was collected in all patients at random assignment and at week 37 visit. We investigated TRA rates and whether TRA in patients with hormone receptor-positive and -negative tumors would impact disease-free survival (DFS) and overall survival (OS). Landmark and time-dependent modeling were used to account for guarantee-time bias. All statistical tests were two-sided. Results:A total of 2862 premenopausal women were included, of whom 1679 (58.7%) had hormone receptor-positive disease. Median age was 43 (interquartile range = 38-47) years. Similar TRA rates were observed in the trastuzumab (72.6%), lapatinib (74.0%), trastuzumab?lapatinib (72.1%), and trastuzumab+lapatinib (74.8%) arms (P = .64). The association between TRA and survival outcomes differed according to hormone-receptor status (Pinteraction for DFS = .007; Pinteraction for OS = .003). For hormone receptor-positive patients, the TRA cohort had statistically significantly better DFS (adjusted hazard ratio [aHR] = 0.58, 95% confidence interval [CI] = 0.45 to 0.76) and OS (aHR = 0.63, 95% CI = 0.40 to 0.99) than the no TRA cohort. No difference was observed in hormone receptor-negative patients. Conclusions:In this unplanned analysis, no association between TRA rate and type of anti-HER2 treatment was observed. TRA was associated with statistically significant survival benefits in premenopausal hormone receptor-positive/HER2-positive early breast cancer patients.