HIGH-DOSE CHEMOTHERAPY IN PATIENTS WITH BREAST-CANCER - EVALUATION OFINFUSING PERIPHERAL-BLOOD STEM-CELLS CONTAINING OCCULT TUMOR-CELLS

The purpose of this study was to evaluate the frequency of detecting o ccult tumor cells in peripheral blood stem cell (PBSC) harvests and to determine the impact of infusing such cells on relapses after high-do se chemotherapy (HDC). Peripheral blood stem cell harvests from 223 pa tients with breast cancer were examined by an immunocytochemistry (ICC ) method for detection of occult tumor cells, and infused after HDC wi thout consideration of test results. Two hundred and four patients, 11 4 with stage II-III and 90 with stage IV disease who received only PBS C, that were tested by ICC were evaluated for time to relapse. Five hu ndred and eighty-one of 619 PBSC harvests (94%) from 223 patients were tested. Fifty-three of 581 harvests (9%), 8% from stage II-III and 10 % from stage IV patients, were positive by ICC (P=0.68). Forty-one of 223 patients (18%), 17/122 (14%) with stage II-III and 24/101 (24%) wi th stage IV disease, had positive harvests (P = 0.06). Eleven percent of patients who had 1-2 harvests tested were positive as compared to 3 2% of patients who had greater than or equal to 3 PBSC harvests tested (P < 0.001). Nineteen patients who were infused with a mixture of ICC negative and untested PBSC harvests were excluded from analyses of re lapse. The probabilities of relapse at 18 months for the 97 patients w ith stage II-III disease infused with ICC-negative and the 17 with ICC -positive PBSC were 0.19 and 0.13, respectively (P = 0.48). The probab ilities of relapse at 18 months for patients achieving a CR or a CR in non-bone sites and improvement in bone lesions were 0.55 for the ICC- negative group (n = 30) and 0.45 for the ICC-positive group (n = 11) ( P = 0.60). It was concluded that occult tumor cells were detected by I CC in PBSC harvests from a relatively small fraction of women with bre ast cancer, but were not associated with a significant increase in the probability of early relapse or progression when infused after HDC.