In primary lung cancer surgery, intraoperative pleural lavage cytology (PLC) has been identified as a prognostic marker. However, there have been no reports on PLC for pulmonary metastasectomies. Therefore, the impact of PLC status for patients undergoing pulmonary metastasectomy remains unknown. We aimed to know the incidence and prognostic impact of positive PLC findings in pulmonary metastasectomies.
We retrospectively reviewed patients undergoing pulmonary metastasectomies between January 2013 and December 2018. One hundred and eighty-nine PLC procedures in 159 patients undergoing pulmonary metastasectomy were analyzed. Follow-up information was available in 107 patients who underwent 132 procedure, and they were investigated for pleural recurrence-free probability (PRFP) and overall survival (OS) after pulmonary metastasectomy.
The type of primary lesion was colorectal cancer (101/189, 53%), urothelial/kidney cancer (17/189, 9%), skeletal/soft tissue tumor (18/189, 10%), hepatobiliary/pancreatic cancer (19/189, 10%), uterine/ovarian cancer (14/189, 7%), otorhinolaryngological cancer (11/189, 6%), and other minor lesions (9/189, 5%). Nine PLC-positive metastasectomies were revealed (9/189, 4.8%). They consisted of six metastasectomies from pancreatic cancer, two from osteosarcoma, and one from tongue cancer. Significant predictors for PLC status was type of primary tumor (P < 0.001). PRFP and OS rate of PLC-positive group were significantly lower than PLC-negative (P < 0.001, respectively).
PLC-positive results were rarely seen in pulmonary metastasectomies. PLC status was associated with the incidence of ipsilateral pleural recurrence and survival after metastasectomy. Cytologic examination of PLC should be considered in patients undergoing pulmonary metastasectomy.

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