In this study, we observe the patterns initial palliative treatment for premenopausal patients with HR-positive/HER2-negative MBC and determine if non-adherence to clinical guidelines are associated with worse clinical outcomes in terms of progression-free survival (PFS) and overall survival (OS) in the South Korean population.
A retrospective review was performed for premenopausal patients diagnosed with HR-positive MBC between October 1997 and May 2016 who received palliative systemic treatments at a large tertiary medical center. Survival outcomes were analyzed according to the palliative treatment received prior to disease progression.
The review identified a total of 272 premenopausal patients with HR-positive/HER2-negative MBC. The patients were young (median age, 39 years), as per the premenopausal criteria. Chemotherapy alone was first-line palliative treatment in 78 patients, with endocrine therapy as the initial treatment in 133 patients. In 57 patients, the first line treatment was switched from chemotherapy to endocrine treatment prior to any disease progression. Both progression free survival and overall survival were significantly longer for chemotherapy-endocrine therapy (median PFS 18.2 months and OS 85.2 months) than for chemotherapy-alone (median PFS 12.6 months and OS 45.5 months) or endocrine therapy-alone (median PFS 7.0 months and OS 57.3 months) (all P values < 0.01). In multivariate analysis, chemotherapy-endocrine therapy was an independent predictive value for improved PFS and OS (hazard ratio [HR] 0.33, 95% CI 0.20-0.52, P < 0.001; HR 0.38, 95% CI 0.19-0.73, P = 0.004).
In our study population, chemotherapy alone was not objectively inferior to endocrine therapy as the initial palliative treatment. In addition, chemotherapy followed by endocrine therapy was associated with objective higher response rate than endocrine therapy alone. Further studies should explore the relationship between non-adherent treatment patterns and patient outcomes across the largely premenopausal breast cancer populations across Asian countries.
Clinical trial identification
Legal entity responsible for the study
Prof. Yeon Hee Park
All authors have declared no conflicts of interest.