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Department of Oncology – Observational Study Protocol

Title:

Treatment Patterns and Determinants of Second and ThirdLine Therapy Selection in Older Adults with HR+/HER2 Metastatic Breast Cancer: A Departmental Observational Study

1.      Background:

Hormone receptorpositive (HR+), HER2negative metastatic breast cancer (MBC) is common in older adults. Treatment beyond firstline therapy involves complex decisionmaking influenced by comorbidities, functional status, and prior treatment response. There is limited realworld data specifically addressing treatment choices in patients aged 70 years and above.

2.      Study Objectives:

 Primary Objective:

·        To observe and analyze the realworld treatment patterns for second and thirdline therapy in patients aged >70 years with HR+/HER2 metastatic breast cancer.

 Secondary Objectives:

·        To identify clinical and geriatric factors influencing treatment selection.

·        To assess tolerability and shortterm outcomes associated with different treatment regimens.

·        To evaluate the impact of treatment choice on functional status and quality of life indicators (as documented in medical records).

3.      Study Design:

Type: Prospective/Retrospective observational cohort study (based on available resources).

Setting: Oncology Department, KSBL and Private practice

4.      Inclusion Criteria:

·        Female or male patients aged ≥65 years at time of diagnosis

·        Confirmed diagnosis of HR+/HER2 metastatic breast cancer.

·        Minimum of one prior line of systemic therapy for metastatic disease.

5.      Exclusion Criteria:

·        HER2positive or triplenegative disease.

·        Patients enrolled in interventional clinical trials for the same indication.

·        Incomplete clinical records or lack of followup data.

Data Collection Parameters:

·        Demographics: Age, sex, comorbidities (Charlson Comorbidity Index if available).

·        Tumor Characteristics: ER/PR status, site of metastasis, disease burden.

·        Treatment History: Previous lines of therapy, duration of response, reason for change.

·        Treatment Selection Factors: Physician rationale, functional assessment (ECOG, ADLs), patient preference, lab parameters.

·        Treatment Regimen Details: Drug(s), dose modifications, schedule.

·        Lab parameters : Albumin, CRP, Neut, Lymph, LDH, Vitamin D at diagnosis or within 1-3 months during diagnosis

·        Outcomes: Tolerability (dose reductions, adverse events), progression (if documented), and performance status posttherapy.

Data Analysis:

Descriptive statistics will summarize treatment patterns and patient characteristics. Logistic regression may be applied to assess factors associated with specific treatment choices, depending on sample size.

Ethical Considerations:

As this is an observational study with anonymized data collection from standard clinical practice, formal ethics committee approval will be sought. (Weiterverwendung ohne Einwilligung) Informed consent will be waived or obtained based on the retrospective or prospective nature of the study.

Expected Impact:

This study aims to enhance understanding of realworld decisionmaking in older patients with MBC, supporting more personalized and evidenceinformed treatment pathways in our clinical practice.