Background: Globally, the incidence and death rate from of breast cancer (BC) are rising quickly; by 2040, there may be one million deaths and over 3 million new cases of BC. Various studies assessed the usefulness of DNA integrity index (DII) as marker for diagnosis and prognosis in variety of solid tumors. Objectives: We aimed to evaluate DII's clinical usefulness as a molecular marker for BC detection, prognosis prediction and assessment of tumor burden in Egyptian BC female patients. Methods: This study included 150 female patients with BC, and 75 healthy controls. Measurement of cfDNA ALU 115 and 247 fragments was by real-time polymerase chain reaction and DII was calculated. Results: In comparison to controls, BC patients had a highly statistically significant rise in DII (p=<0.001). A highly significant increase in DII was observed in cases with early stages compared to controls (p=<0.001). Also, it was showed that patients with metastasis had greater levels of DII than patients without metastasis (p=0.002). DII was positively correlated with tumor size (r=0.64 , p= <0.001) and with stage(r=0.73, p=<0.001). ROC curve was constructed using DII to discriminate between BC cases and controls. The optimal cut off was greater than 0.51 with sensitivity 88%, specificity 92%, PPV 96%, NPV 79% and the AUC was 0.95 with 95% CI (0.90-0.99). Conclusions: This study suggests the possible use of DII as promising adjuvant marker in early BC detection, and it may be used as a prognostic biomarker for detection of BC tumor progression and tumor burden