Is systemic anticancer therapy associated with higher rates of malignant pleural effusion control in people with pharmacologically-sensitive tumours? A retrospective analysis of prospectively collected data.

Background Malignant pleural effusions (MPEs) often cause symptoms, and guidelines recommend early definitive intervention. However, observational data suggest that systemic anticancer treatment (SACT) may control MPE because of certain pharmacologically sensitive tumors. Research Question Is SACT associated with higher rates of MPE resolution in people with pharmacologically sensitive tumors? Study Design and Methods This was a retrospective analysis of prospectively collected data from an observational cohort study of people diagnosed with MPE from lung, breast, ovarian, and hematologic malignancy between May 11, 2008, and August 6, 2017. MPE resolution (defined as radiologic resolution with removal of drain or catheter and cessation of interventions) was compared in pharmacologically sensitive (high-grade lymphoma, small cell or target-mutation-positive lung cancer, and hormone-receptor-positive breast or ovarian cancer) and nonsensitive (remainder of cohort) tumors, with and without SACT. Secondary outcomes included time to resolution, 3-month resolution rates, and total pleural interventions. Results Of 280 patients, 127 had sensitive and 153 had nonsensitive tumors. One hundred seventy-one received SACT, and 109 did not. More patients with sensitive tumors achieved MPE resolution than those with nonsensitive tumors (53/127 [41.7%] vs 42/153 [27.5%]; P = .01), and this occurred predominantly after receipt of SACT. However, hematologic malignancies were overrepresented in the sensitive group, with high rates of SACT use and MPE resolution. After adjustment for this and other confounders, no relationship was found among pharmacologic sensitivity, SACT, and MPE resolution (adjusted OR, 1.4; 95% CI, 0.5-4.1). The strongest predictor of MPE resolution was administration of chemical pleurodesis (adjusted OR, 6.2; 95% CI, 3.3-11.7). In sensitive tumors, MPE resolution occurred without chemical pleurodesis in 14 or 52 patients (26.9%; 95% CI, 15.6%-41.1%) after SACT and in 5 of 22 patients (22.7%; 95% CI, 8.2%-47.2%) without SACT. Interpretation In this observational study, SACT was not associated independently with MPE resolution in pharmacologically sensitive tumors. Randomized trials are required, but with current data, patients with symptomatic MPE should receive early definitive pleural intervention regardless of underlying tumor or intended treatment.