Tract seeding in indwelling pleural catheter placement for the drainage of malignant pleural effusions: Incidence and related clinical and imaging factors

Background: The incidence of tract seeding after the placement of indwelling pleural catheter (IPC) for malignant pleural effusion drainage has been variable in the literature.Research question: To evaluate the incidence of IPC-related cancer tract seeding and find out related demographic, clinical or imaging factors to the tract seeding.Study design and methods: This retrospective study included 124 consecutive patients seen between January 2011 and December 2021 who underwent IPC placement for malignant pleural effusion drainage. Chest radiographs before IPC placement and serial chest CT studies were obtained. One patient was diagnosed pathologically, and the other patients were diagnosed as tract seeding radiologically. The incidence of and related factors to tract seeding were assessed by reviewing medical records and imaging studies.Results: The incidence of IPC tract seeding was 21.7% (27 of 124 malignant effusions). Of 27 patients, 15 had primary lung cancer and remaining 12 had extra-thoracic malignancy. Adenocarcinoma (19 of 27, 70.3%) either from the lung (N = 12) or extra-thoracic malignancy (N = 7) was the most common cell type. Mean time elapsed until tract seeding occurrence after IPC placement was 96 days (ranges; 28-306 days). The survival in seeding group after IPC placement was 185 days (ranges, 32-457 days). On odd ratio analysis, the presence of mediastinal pleural thickening (OR [95% CI]; 9.79 (2.67-35.84), p = 0.001) was significantly related to the occurrence of tract seeding. Neither tumor volume within pleural space (p = 0.168), duration of IPC indwelling (p = 0.142), days of survival after IPC placement (p = 0.26), nor pleural effusion amount (p = 0.481) was related to the tract seeding.Interpretation: IPC tract seeding is seen in 27 (21.7%) of 124 malignant pleural effusion patients, particularly with adenocarcinoma cytology. CT features of mediastinal pleural thickening are related to the occurrence of tract seeding.