Patients and Methods: We studied retrospectively cryopreserved bone marrow aspirates from 83 patients with high-risk stage II, III, and IV breast cancer obtained before bone marrow harvest but after induction chemotherapy, All samples were histologically negative for metastases. Polymerase chain reaction (PCR) for K19 was performed according to methods described previously and results were correlated with the probability of relapse following HDCT and ABMT.

Results: The incidence of occult metastases as defined by PCR for K19 message was 52% for 19 stage II, 57% for 14 stage III, and 82% for 50 stage IV patients (two-tailed P = .0075(r) chi(2) test). The probability of relapse at 3 years after ABMT was 32% and 94% for K19-positive stage II/III and stage IV patients, respectively, versus 10% and 14% for K19-negative stage II/III and stage IV patients, respectively, The difference was significant for stage IV patients (two-tailed P = .0002).

Conclusion: It has been shown that PCR is a highly sensitive method to detect K19 message in the bone marrow, The incidence of K19 positivity in bone marrow increases significantly with advancing stage. In patients with breast cancer, especially metastatic breast cancer, undergoing HDCT and ABMT, the presence of K19 is associated with a poor prognosis. (C) 1996 by American Society of Clinical Oncology.