engleski

Do We Follow The Current Guidelines For The Treatment Of Metastatic Hormone-Dependent, Her2 Negative Breast Cancer With CharacteristicsOf Endocrine Resistance? Retrospective Analysis Of Patients Treated With Cdk 4/6 Inhibitors In Uhc Zagreb

Introduction: According to the 5th ESO-ESMO International Guidelines for Advanced Breast Cancer, primary endocrine resistance is defined as recurrence during the first 2 years of adjuvant endocrine therapy (ET) or disease progression within the first 6 months of first-line ET for metastatic breast cancer (mBC). The same guidelines define secondary endocrine resistance as disease progression during or within 12 months of finishing adjuvant ET but after the first 2 years of treatment or progression after 6 or more months of ET for mBC. CDK 4/6 inhibitors in combination with ET are indicated as treatment for hormone sensitive (HR+) HER2 negative (–) mBC. For endocrine resistant population, the optimal endocrine partner of CDK4/6 inhibitor is fulvestrant. The aim of this study was to determine how much we adhere to the guidelines for treatment of the endocrine-resistant population in everyday clinical practice. Methods: We conducted a retrospective observational cross- sectional study by analyzing UHC Zagreb database for the 203 patients with HR+HER– mBC treated with CDK 4/6 inhibitors (palbociklib, ribociclib and abemaciclib). Of these, 83 were endocrine sensitive, 37 primary endocrine resistant, and 83 secondary resistant. Among the endocrine-resistant patients, we singled out 13 patients for whom the criteria of non-compliance with the guidelines was met. Result: Median patients’ age was 62 years (30–84) and the median follow-up was 12 months (1– 32). Of 120 endocrine-resistant, 13 patients progressed during or within 12 months of finishing adjuvant endocrine therapy, and as an endocrine partner of CDK 4/6 inhibitor an aromatase inhibitor was administered instead of the recommended fulvestrant. Conclusion: A retrospective analysis of endocrine resistant cohort revealed that although optimal endocrine partner of CDK4/6 inhibitor in this population is fulvestrant, this fact was overlooked in 10.8% of patients. A larger number of patients and longer follow-up are needed to analyze progression-free survival in the group of patients whose treatment was inconsistent with the guidelines.

metastatic, breast cancer, endocrine resistance, CDK4/6

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