Malignant pleural effusions after resection of pulmonary adenocarcinoma.

Objective: To evaluate the clinicopathologic features of malignant pleural effusions secondary to pulmonary adenocarcinoma in patients who have undergone surgical resection of the primary tumor.

Study Design: Clinical, pathologic and cytologic material from 19 patients who developed malignant pleural effusions after resection of pulmonary adenocarcinoma was reviewed.

Results: Malignant effusions developed only in patients with either lymph node or pleural involvement by neoplasm. Time to development of the effusion after resection and overall survival correlated with histologic findings. Malignant effusions in patients who survived > 24 months were secondary to another primary tumor (either breast or a new pulmonary carcinoma). Malignant effusions developed significantly sooner after resection (mean 5.0 +/- 2.0 months, median 5) in patients with lymph nodal metastases than in those with pleural involvement by neoplasm (mean 11.2 +/- 2.5 months, median 12) (Student's t test P = .01, Mann-Whitney U test .04). Nevertheless, survival after resection for patients with lymph node involvement (mean 9.0 +/- 3.6 months, median 8) and those with pleural involvement (mean 12.3 +/- 2.5 months, median 12) was not significantly different.

Conclusion: Malignant effusions developing in patients more than two years following resection of a pulmonary adenocarcinoma are likely to be secondary to another primary neoplasm. Lymph node and pleural involvement at the time of resection are risk factors for the development of a malignant effusion. Patients with lymph node involvement develop malignant effusions sooner than those with pleural involvement, but the overall survival is not significantly different.