Objective:

To study the real-world patient characteristics, including age and age- and frailty-related comorbidities, of breast cancer patients prescribed CDK inhibitors and to compare survival outcomes across different age groups based on these characteristics.

Approach:

• Study Cohort: Identified patients aged ≥ 18 years with first diagnosis of breast cancer from the Finnish Cancer Registry between 2000 and 2020, totaling 91,279 cases.
• Drug Exposure: Extracted data on reimbursed prescription drugs for CDK inhibitors from national health databases for the years 2018 to 2022.
• Comorbidities: Gathered data on comorbidities from multiple health registers, including diagnoses from inpatient and outpatient visits.

Key Findings:

• Older adults with breast cancer exhibit worse overall survival compared to younger patients, despite receiving similar treatment benefits as indicated by the data.
• The presence of comorbidities in older patients may influence their treatment tolerance and overall life expectancy.

Interpretation:

The study provides insights into the impact of age and comorbidities on treatment outcomes in older breast cancer patients receiving CDK inhibitors.

Limitations:

• The underrepresentation of older adults in clinical trials may limit the applicability of the findings to this population.
• Real-world data may not capture all relevant factors that influence survival outcomes, potentially affecting the study's conclusions.

Conclusion:

The analysis contextualizes real-world breast cancer patient demographics in relation to clinical trial data, highlighting the importance of considering age and comorbidities in treatment decisions.