Efficacy of large-volume plasma exchange in patients with chemotherapy-resistant metastatic colorectal cancer.

ABSTRACT

23 patients with advanced metastatic colorectal adenocarcinoma and measurable metastases were treated with chemotherapy until resistance to chemotherapy was evident. Chemotherapy was then not discontinued but administered for at least a further cycle combined with large-volume plasma exchange (PE). 15 of 23 patients responded again for 4-45 weeks, an average of 13. This effect was thought to be due to dilution or elimination of serum-blocking factors, which could be measured by mixed lymphocyte culture (MLC) assay. 16 of 20 patients showed a positive correlation between the clinical course and MLC activity, if the basic MLC reactivity was compared with the MLC levels at the start of each subsequent PE in each patient. It is postulated that in some tumors there is a resistance to chemotherapy mediated by plasma-blocking factors.