Objectives: This prospective study was performed to examine whether tumour cells are detectable in the tumour draining vein of patients with non-small cell lung cancer. Furthermore, the impact of these cells on the clinical course was analysed.
Patients and methods: Sixty-two consecutive patients with completely resected primary non-small cell lung cancer (pT1-4 pN0-2 M0) were admitted to the study. Pulmonary venous blood was drawn at the time of surgery for primary non-small cell lung cancer. The tumour draining vein was punctured subsequent to thoracotomy prior to manipulation of the tumour. The blood samples were examined for occult tumour cells by immunocytochemical staining of cytospins using the pancytokeratin antibody A45-B/B3 (murine immunoglobulin G1; Micromet, Munich, Germany).
Results: Disseminated cancer cells in pulmonary venous blood were observed in 11 of 62 patients (18%) and did not correlate with standard clinico-pathological parameters. In patients without involvement of mediastinal lymph nodes (pN0-pN1), detection of occult tumour cells was an independent prognostic parameter for unfavourable outcome: log rank analysis showed a significant association of occult tumour cells in pulmonary venous blood with shortened cancer-related survival (P=0.019) and multivariate regression analysis demonstrated an independently significant (P=0.004) prognostic impact.
Conclusion: The present study shows that disseminated cancer cells in the pulmonary venous blood are detectable in about 20% of the patients with operable non-small cell lung cancer and that they are associated with a poor clinical outcome. Therefore, the detection of such cells might be useful for the identification of patients who benefit from adjuvant therapy. Furthermore, in order to avoid an additional systemic spread of tumour cells intraoperatively, the pulmonary veins should be ligated first during lung cancer surgery.