Utilization and Diagnostic Value of CA-15.3 Test in Breast Cancer: Insights from a Longitudinal Study Based on Turkish Ministry of Health Data

Aim: The objective of this study was to analyze the utilization of the CA-15.3 test for breast cancer monitoring and treatment and evaluate its patterns across different populations. Materials and Method: Data from a five-year period (2017-2021) were collected, including 21.579.044 CA-15.3 tests from 2.981.142 individuals. Descriptive statistics were used to analyze the data, including test counts, test rates per population, rates of exceeding the reference range, and cancer diagnosis rates. Results: The study revealed an increasing trend in the number of CA-15.3 tests requested from 2017 to 2019, followed by a significant decrease in 2020 and 2021. The test was more frequently requested for women, particularly in the age group of 18-64. The rate of cancer diagnosis in individuals undergoing the CA-15.3 test also showed an upward trend over the years. Istanbul had the highest test request rate, followed by Ankara and Izmir. University hospitals requested the most tests, followed by state hospitals, private hospitals, and training and research hospitals. Conclusion: The study provides valuable insights into the utilization patterns of the CA-15.3 test in breast cancer management. While the test showed an increasing trend in test requests and cancer diagnosis rates, caution should be exercised in interpreting the results due to potential limitations. Further research is needed to establish a definitive understanding of the relationship between CA-15.3 levels and cancer diagnosis. The findings emphasize the importance of personalized interpretation of test results and the need for comprehensive studies to validate these findings.