Cytokeratin-positive cell dissemination in patients within situ ductal carcinoma of the breast

Abstract

Dear Sir, We conducted a study recently on the presence of cytokeratin C-19 positive cells in peripheral blood of breast cancer patients as an indirect marker for metastatic disease. Between July 1998 and November 2002, 517 EDTA blood samples were taken from 353 female patients with a mean age of 55.2 years (range 34.6–77.4) before and after breast surgery. Cells were enriched by density gradient separation on Ficoll Hypaque (Pharmacia, Uppsala, Sweden), fixed to polylysinecoated slides and stained with commercially available anticytokeratin C-19 antibodies (Epimet Kit, Baxter, Germany).1 Each sample was screened blinded by two independent individuals under bright-field microscopy. The criteria for immunohistochemical staining were used to identify cells and samples were diagnosed positive when at least one single cytokeratin-positive cell was detected. All patients were classified for tumour stage and grade according to Union Internationale Contre le Cancer (UICC) criteria. Cytokeratin-positive cells were detected in 22 (6.2%) of 353 patients who had no signs of metastatic disease, assessed by means of chest X-ray, liver ultrasound and bone scanning. Most interestingly, 4 patients with positive cell dissemination had in situ ductal carcinoma. Diagnosis was confirmed twice by independent pathologists. All four patients were found to be free of both lymph node and distant metastases at time of blood sampling. Tumours were graded G2 (n 3) and G3 (n 1). After an observation period of 11.6–56.7 months all patients are disease-free. Evidently, bone marrow is invaded early by disseminated breast cancer cells. Metastatic disease may develop even after R0 resection of early stage cancers many years after the procedure.2 Braun et al.3 reported cytokeratin-positive cells in 1% of disease-free patients. This figure may be even higher when using more sensitive polymerase chain reaction (PCR). Nevertheless, immunostaining is a very sensitive method for detecting one tumour cell in one million mononuclear cells.1 A novel finding of our study was the detection of cytokeratin-positive cells in blood samples of 4 patients with in situ ductal carcinoma. It remains unclear, however, whether these cells are of potential malignancy or whether they derive from non-malignant epithelium. Precise specificity and sensitivity of this technique remains to be evaluated in further investigations. The observation period in this study was too short to assess the prognostic value of cytokeratin-positive cells in patients with in situ ductal carcinoma, but these facts emphasize that breast cancer, even in earliest stages, must be considered a generalized disease. Future planning of adjuvant chemotherapy could be based on both histologic results as well as the more sophisticated evaluation of tumour cells in blood or bone marrow. Yours sincerely, Ingrid STELZMUELLER, Paul HENGSTER, Peter OBRIST, Martina DUENSER, Raimund MARGREITER and Helmut WEISS