Isolated organ perfusion does not result in systemic microembolization of tumor cells

Background: Isolated organ perfusion with hyperthermia and melphalan with o r without tumor necrosis factor-alpha has been effectively used to treat re gionally confined, unresectable malignancies of both the limb and liver. Ma ny patients, however, will eventually relapse at distant sites. We used rev erse transcription-polymerase chain reaction (RT-PCR) to determine whether significant tumor microembolization occurs in patients undergoing isolated limb perfusion (ILP), isolated hepatic perfusion (MP), of hepatic resection , Methods: Primers specific for the human tyrosinase gene or carcinoembryonic antigen gene were designed for RT-PCR to screen melanoma or colon adenocar cinoma, respectively. RNA from human melanoma lines (Pmel and 1286) and hum an colon adenocarcinoma lines (H508 and HT29) were used to generate positiv e control cDNA, Normal human blood was inoculated with tumor cells at conce ntrations that ranged from 10(-2) to 10(5) tumor cells/ml of blood to defin e the sensitivity. Systemic and perfusate blood samples were drawn from 15 patients (8 patients underwent IHP, 5 patients underwent ILP, and 2 patient s underwent resection) before the start of the operation, immediately befor e and during the perfusion, and postoperatively. Mononuclear cell fractions were separated from the blood samples and RNA was extracted fur the RT-PCR assay. Standard primers for human beta-actin were used to confirm that cDN A was generated after the RT reaction. Results: RT-PCR assay sensitivity was determined to be 10 tumor cells/ml of whole blood. Of the 8 IHP patients, 6 had colon metastases and 2 had ocula r melanoma metastases to the liver. All 5 ILP patients had in transit melan oma of the extremity. Two patients with colon metastases to the liver were found to have resectable disease. There were no detectable circulating tumo r cells in the systemic circulation either preoperatively or postoperativel y in all 15 patients that were screened. Conclusions: RT-PCR is a highly sensitive method of detecting tumor cells i n perfusate or blood. Manipulation of the Limb or liver followed by resecti on or isolated hyperthermic perfusion does not cause detectable release of circulating tumor cells. The late development of distant metastases observe d in many of these patients does not correlate with the ability to measure circulating tumor cells during regional therapy.