Serum Prostate-Specific Antigen as a Biomarker in Breast Carcinoma: A Hospital-Based Case-Control Study

Abstract

Background: Breast carcinoma is the most frequently diagnosed malignancy in Indian women and continues to present at locally advanced stages. Prostate-specific antigen (PSA), historically regarded as prostate-specific, is now known to be expressed at low concentrations in female breast tissue and serum. Its diagnostic role in breast carcinoma remains contested. Objectives: To evaluate serum PSA (sPSA) as a biomarker for the diagnosis of breast carcinoma and to examine its association with clinical staging. Methods: A hospital-based observational case-control study was conducted in the Department of General Surgery, JSS Medical College and Hospital, Mysuru, between April 2024 and September 2025. Eighty women were enrolled: 40 cases with histopathologically confirmed breast malignancy and 40 controls with newly diagnosed benign breast disease. Serum PSA was estimated using a standardised chemiluminescent immunoassay (reference range 0–1.4 ng/mL). Statistical analyses included Chi-square test, independent t-test, one-way ANOVA and Pearson correlation, with p<0.05 considered significant. Results: Cases were significantly older than controls (mean 51.58 ± 9.97 vs 25.25 ± 5.45 years, p<0.001) and predominantly post-menopausal (52.5%). Invasive ductal carcinoma accounted for 85.0% of malignancies, and Stage III disease for 42.5% of cases. Serum PSA was detectable in 100.0% of cases (0.003–0.008 ng/mL) versus 55.0% of controls (0.003–0.006 ng/mL) (χ²=20.717, p<0.001), although all values remained below the 1.4 ng/mL threshold. Detection-based diagnostic performance yielded sensitivity 100.0%, specificity 45.0%, positive predictive value 64.5%, negative predictive value 100.0% and accuracy 72.5%. No significant association was observed with clinical stage (p=0.576), T stage (p=0.174), N stage (p=0.841) or lump size (r=-0.128, p=0.432). Conclusion: Although absolute sPSA values remained below the conventional reference threshold, qualitative detectability of sPSA significantly distinguished malignant from benign breast disease. Serum PSA may serve as a minimally invasive rule-out biomarker but lacks specificity for confirmation and does not correlate with disease extent.