West Asia Organization for Cancer Prevention (WAOCP), APOCP's West Asia Chapter. Asian Pacific Journal of Cancer Prevention 1513-7368 27 6 2026 06 01 Combined Diagnostic Utility of Serum CA15-3 and Routine Hematological Indicators for Breast Cancer Differentiation in an Iraqi Cohort 2251 2258 92259 10.31557/APJCP.2026.27.6.2251 EN Mohammed Jaber Mohaibes Department of Radiology and Sonar Techniques, College of Health and Medical Techniques, Gilgamesh University, 10022 Karkh, Baghdad, Iraq. 0009-0009-7458-6626 Mayada Al-Khafaji Department of Medical Laboratories Techniques, College of Health and Medical Techniques, Gilgamesh University, Baghdad, Iraq. 0009-0001-7484-8296 Fakhria Muhaibes College of Nursing, University of Al-Mustaqbal, Babylon, Iraq. 0000-0002-1269-2302 Journal Article 2025 11 03 Background: Breast cancer (BC) is a leading cause of mortality among Iraqi women, underscoring the need for accessible diagnostic tools. This study evaluates the combined utility of the tumor marker CA15-3 and routine hematological parameters as an adjunctive tool for distinguishing between treatment-naïve BC patients with a pre-existing diagnosis and healthy individuals. Methods: In this case-control study, 100 female BC patients (Group I) and 50 healthy controls (Group II) were recruited. Serum CA15-3 levels were measured using electrochemiluminescence immunoassay (ECLIA), and a complete blood count was performed. Statistical analyses included independent t-tests, ROC curve analysis, and logistic regression to develop a combined diagnostic model. All BC patients were treatment-naïve and were required to submit blood samples prior to undergoing any surgical procedure, although they had already been diagnosed. Results: CA15-3 levels were significantly higher in BC patients (26.1 ± 7.5 U/mL) than in controls (7.54 ± 2.6 U/mL; P < 0.001). Significant differences were also observed in white blood cell (WBC), red blood cell (RBC), lymphocyte, and platelet counts (all P < 0.05). ROC analysis showed excellent diagnostic performance for CA15-3 alone (AUC = 0.98). A combined model integrating CA15-3 with the four hematological parameters achieved a superior AUC of 0.99, with 96% sensitivity and specificity. Conclusion: Elevated CA15-3 is confirmed as a key diagnostic marker for BC. Integrating CA15-3 with specific, routinely measured hematological indicators provides an improved, accessible, and cost-effective adjunctive tool for differentiating treatment-naïve BC patients from healthy individuals. This approach may be particularly useful for triaging patients with suspicious symptoms or monitoring those with established diagnoses. https://journal.waocp.org/article_92259_02cfbc9c5ad4963a849988ab0904fc4d.pdf