Detection of micrometastasis in bone marrow of pancreatic cancer patients

Design: Here we applied an immunocytochemical cytokeratin assay that allows the identification of individual pancreatic carcinoma cells disseminated to bone marrow. Patients and methods: Prior to therapy, bone marrow was aspirated from the upper iliac crest of 48 patients with ductal adenocarcinoma of the pancreas at various disease stages as well as an age- matched control group of 33 non-carcinoma patients. Tumor cells in cytologic bone marrow preparations were detected with monoclonal antibodies (mAbs) CK2, KL1 and A45-B/B3 to epithelial cytokeratins (CK), using the alkaline phosphatase anti-alkaline phosphatase method. Results: CK+ cells were found in 25 (52.1%) of 48 cancer patients. The overall frequency of these cells was 1 to 85 per 5x 10⁶ mononuclear cells. 4 (8.3%) cancer patients had specimens that stained with the mAb CK2, compared with 16 (33.3%) patients who displayed KL1+ cells and 9 (18.6%) patients who showed A45-B/B3+ cells. After a median follow up of 22.8 (range 3-48) months, the occurrence of tumor relapse was significantly associated with the outcome of the immunocytochemical screening before the time of primary surgery. 6 (40.0%) out of 15 patients who underwent complete surgical resection but had tumor cells in bone marrow presented with distant metastasis and 7 (46.7%) with local relapse as compared to none of 12 corresponding patients without such cells (p< 0.02). Univariate survival analysis revealed that the presence of CK+ cells in bone marrow was predictive of reduced overall survival (p<0.03). Conclusions: Anti-CK mAbs are reliable probes for the immunocytochemical detection of single pancreatic cancer cells disseminated to bone marrow. Thus the described technique may help to identify patients with pancreatic cancer and potential high risk of early metastic relapse. The results promise to be of important assistance in determining prognosis and consequences in therapy of early stage pancreatic cancer.