The sequence of vessel ligation affects tumor release into the circulation

Objective: Whether the sequence of pulmonary vein and artery ligation in pulmonary lobectomy for carcinoma affects intraoperative hematogenous cancer cell dissemination is not known. We examined whether vessel ligation sequence affects the presence of circulating cancer cells as reflected by carcinoembryonic antigen messenger ribonucleic acid. Methods: We assayed for the transcripts of carcinoembryonic antigen messenger ribonucleic acid by reverse-transcriptase polymerase chain reaction in peripheral blood taken before, during, and after operation from 30 patients with non-small-cell lung cancer who underwent a curative lobectomy and from six patients,vith limited-stage small-cell lung cancer who were treated initially with chemotherapy followed by lobectomy, Each patient was randomly assigned before the operation to have either pulmonary vein ligation or pulmonary artery ligation first. Blood taken from 10 patients with interstitial pulmonary fibrosis who underwent an open lung biopsy and 41 healthy subjects served as a control. Results: No control samples were positive for transcripts. Sixteen of the preoperative blood samples from the 30 patients with non-small-cell cancers were positive. Of these 16, eight samples remained positive even after lobectomy was performed; the remaining eight samples (four in each ligation group) became negative. Of the 14 initially negative samples (seven in each ligation group), nine samples became positive during the operation. Such conversion during the operation was more common with arterial ligation first (six patients, 85.7%) than with venous ligation first (three patients, 42.9%), Samples from all six patients with small-cell cancer were positive before the operation, and five of six samples remained positive after the operation. Conclusions: Many patients with non-small-cell lung cancer have systemic disease even when they were thought to have resectable tumors. Ligating the pulmonary vein before ligating the artery may lessen intraoperative hematogenous dissemination. Most small-cell lung cancers represent systemic disease even when considered resectable.