Evaluation of a Standardized Protocol of Intracavitary Recombinant Interferon Alpha-2b in the Palliative Treatment of Malignant Peritoneal Effusions

<i>Objective:</i> Several schedules with variable doses of intracavitary interferon have been proposed for the management of metastatic peritoneal effusions. This prospective pilot study evaluated the efficacy of a standardized schedule of intraperitoneal interferon α_2b. <i>Methods:</i> In 41 cancer patients with malignant ascites a 9-french intraperitoneal catheter was placed under sonographic guidance, and ascites was drained until abdominal ultrasound showed complete absence of effusion. Interferon α_2b, 6 or 9 million units (body weight ≤ or >50 kg, respectively), was then administered via the tube, which was clamped for 6 h. 6 courses were given at 4-day intervals. In comparison with pretreatment levels, the 30-day response was classified as complete (CR) = no fluid recurrence, partial (PR) = fluid recurrence <50% and no response (NR) = >50%. Responders were monitored until fluid recurrence requiring paracentesis. <i>Results:</i> 12 patients had CR, 15 PR, 14 NR. Global response (GR) was 65.9%. In ovarian cancer, GR was 75% and was not influenced by the quantity of the pretreatment daily fluid production. In the other cancers, a pretreatment fluid production ≤500 ml/day was associated with a significantly higher response (p < 0.05). Patients not showing response within the first 3 courses did not respond after the next courses. 60-day GR was 41.5%, 90-day GR was 26.8%. The mean time to fluid reaccumulation was 70.5 ± 75.3 versus 11.4 ± 4.4 days before treatment (p < 0.001). The survival of responders was 38–394 days (mean 131), and the average duration of response was 101 days. <i>Conclusion:</i> This protocol could be reasonably applied to ovarian cancer patients and to patients with other cancers having a fluid production of ≤500 ml/day, and it should be stopped if no response is observed after 3 courses of treatment.