Long-term outcome of pleurodesis with OK-432 in metastatic breast cancer: a new risk model for success from an analysis of 75 cases

Malignant pleural effusion is a common and devastating complication of metastatic breast cancer. This occurs in about 30% of patients with metastatic breast cancer during the clinical course, and chemical pleurodesis is sometimes performed to relieve dyspnea. However, the long-term outcome of pleurodesis and factors affecting successful pleurodesis have not been clarified.The aim of this analysis is to evaluate the long-term outcome of pleurodesis and to identify risk factors associated with success.Data on 75 patients who had undergone chemical pleurodesis with OK-432 for pleural effusion due to metastatic breast cancer were reviewed retrospectively. The primary outcomes were success rate and pleural progression-free survival (PPFS) rate.The median duration of follow-up was 134 days (range 8-975 days). During this period, 22 patients re-accumulated pleural fluid. The overall success rate was 70.5%. The 4-, 8- and 12-week PPFS rates were 88.0, 84.0 and 78.7% respectively. Multivariate analysis identified three unfavorable factors that were independently associated with unsuccessful pleurodesis, including estrogen-receptor negative status, a 24-h drainage volume of more than 100 mL before extubation and NSAID use. The PPFS rate at median follow-up was 93.5% in the low-risk group (n = 41, 0 or 1 unfavorable factor) and 55.1% in the high-risk group (n = 34, 2 or 3 unfavorable factors). The difference between the PPFS curves of the two risk groups was statistically significant (P0.001).Pleurodesis for metastatic breast cancer was efficacious in controlling malignant pleural effusion. Our simple new risk model warrants further studies.