First-line endocrine therapy for advanced breast cancer. A real-world study at a Latin American university health institution

Progression-free survival on endocrine therapy, before or after chemotherapy, in hormone receptor-positive HER2-negative metastatic breast cancer

PURPOSE

A major question when treating HR+/HER2- metastatic breast cancer (MBC) is whether early introduction of chemotherapy (CT) increases endocrine resistance. We aimed to describe progression-free survival (PFS) under first endocrine therapy (ET) depending on whether given before or after CT in a large nationwide cohort, in the pre-CDK era.

METHODS

The real-life retrospective ESME database includes all patients with MBC whose first-line treatment was initiated between 2008 and 2014 in one of the 18 French Comprehensive Cancer Centres. Our primary objective was to compare PFS from start of first ET in patients with HR+/HER2- MBC who received ET or CT first.

RESULTS

We identified 6293 patients who received at least one ET line during their first two therapeutic lines for MBC. As first-line therapy, 3832 (60.9%) received ET alone (ET1 1st group), whilst 2461 (39.1%) received CT, including 2024 patients (32.2%) with maintenance ET after CT (ET1 after CT group). Median PFS under first ET was 12.4 months (95% CI 11.9-13.1) in ET 1st group vs. 12.6 months in ET1 after CT group (95% CI 12.1-13.4), HR 0.96 (95% CI 0.90-1.01, P = 0.1277).

CONCLUSIONS

PFS under first ET appears identical whether prescribed before or after chemotherapy. These data suggest chemotherapy does not promote endocrine resistance.

Treatment and Monitoring Variability in US Metastatic Breast Cancer Care

PURPOSE

Treatment and monitoring options for patients with metastatic breast cancer (MBC) are increasing, but little is known about variability in care. We sought to improve understanding of MBC care and its correlates by analyzing real-world claims data using a search engine with a novel query language to enable temporal electronic phenotyping.

METHODS

Using the Advanced Cohort Engine, we identified 6,180 women who met criteria for having estrogen receptor-positive, human epidermal growth factor receptor 2-negative MBC from IBM MarketScan US insurance claims (2007-2014). We characterized treatment, monitoring, and hospice usage, along with clinical and nonclinical factors affecting care.

RESULTS

We observed wide variability in treatment modality and monitoring across patients and geography. Most women received first-recorded therapy with endocrine (67%) versus chemotherapy, underwent more computed tomography (CT) (76%) than positron emission tomography-CT, and were monitored using tumor markers (58%). Nearly half (46%) met criteria for aggressive disease, which were associated with receiving chemotherapy first, monitoring primarily with CT, and more frequent imaging. Older age was associated with endocrine therapy first, less frequent imaging, and less use of tumor markers. After controlling for clinical factors, care strategies varied significantly by nonclinical factors (median regional income with first-recorded therapy and imaging type, geographic region with these and with imaging frequency and use of tumor markers; P < .0001).

CONCLUSION

Variability in US MBC care is explained by patient and disease factors and by nonclinical factors such as geographic region, suggesting that treatment decisions are influenced by local practice patterns and/or resources. A search engine designed to express complex electronic phenotypes from longitudinal patient records enables the identification of variability in patient care, helping to define disparities and areas for improvement.

Real-world Data on First-line Systemic Therapy for Hormone Receptor-positive HER2-negative Metastatic Breast Cancer: A Trend Shift in the Era of CDK 4/6 Inhibitors

Hormone receptor-positive (HR⁺) human epidermal growth factor receptor-2 negative (HER2^-) tumors represent the most common subtype of metastatic breast cancer (MBC). International guidelines clearly state that endocrine therapy (ET) should be considered the preferred first-line therapy for these patients in the absence of very symptomatic visceral disease or evidence of endocrine resistance. Nonetheless compliance with guidelines significantly vary worldwide for many different reasons. Historically, a substantial proportion of patients with HR⁺ HER2^- MBC have been treated with chemotherapy (CT) in first-line setting, jeopardizing patients' quality of life without a significant benefit in outcome. In 17 observational studies, including more than 63,000 patients, ET was most frequently used in first-line treatment of HR⁺/HER2^- MBC (range, 42%-87%), nonetheless a high proportion of patients received CT (13%-66%) as initial therapy. More recently, results of clinical trials with CDK 4/6 inhibitors improved response, progression-free and overall survival in this population and are currently the standard of care. There was a trend toward increased use of ET in recent years. This review article aims to evaluate real-world data on patterns of first-line treatment of HR⁺ HER2^- MBC with a special focus on the use of CT in this setting and the potential implications and perceived preliminary changes after the introduction of CDK 4/6 inhibitors.