DNA fingerprints provide a patient-specific breast cancer marker

Background: Detection of systemic breast cancer recurrence is limited by lack of universally expressed tumor cell markers. We hypothesized that a test that detects genetic alterations specific to breast cancer cells of an individual patient would provide a superior cancer marker. Methods: DNA was extracted from blood, primary tumor, and axillary lymph nodes of 33 breast cancer patients and normal breast tissue of 12 control patients. A patient's genome was scanned by PCR amplification between Alu sequences. A DNA fingerprint of approximately 17-40 bands was produced for comparison between normal blood and sampled tissues. Results: There were 7 stage I, 18 stage II, 7 stage III, and 1 stage IV breast cancer cases; 33 of 33 cancer cases showed DNA fingerprint differences between blood and primary tumor (P < .0001).This test predicted 100% of positive nodes. No false-negatives occurred, and in two cases malignancy was detected in histologically negative nodes. Three of the 12 controls showed a single similar band change. Conclusions: DNA fingerprinting is a method for detecting and characterizing genetic alterations specific to an individual patient's primary tumor in 100% of cases tested. These specific changes were also identified in 100% of positive nodes, proving the capacity of the test to detect metastases.