Malignant ascites: Systematic review and guideline for treatment

Abstract

A guideline on the management of symptomatic malignant ascites by abdominal paracentesis, diuretics and peritoneovenous shunting, based on a systematic review of the literature is presented. Thirty-two relevant studies were identified. None were randomized control trials, one was a non-randomized open controlled trial, five were cohort studies or prospective uncontrolled trials, 26 studies were non-analytic studies like case series. Although paracentesis, diuretics and shunting are commonly used procedures, the evidence is weak. Available data show good, although temporary effect of paracentesis on symptom relief. Fluid withdrawal speed and concurrent intravenous hydration is not sufficiently studied. Peritoneovenous shunts can control ascites in patients with malignant ascites, but have to be balanced by the potential risks of this procedure. The available data about diuretics in treatment of malignant ascites are controversial. The use of diuretics therefore should be considered in all patients, but has to be evaluated individually.

Introduction

Malignant ascites is defined as abnormal accumulation of fluid in the peritoneal cavity as a consequence of cancer¹ and presents a difficult clinical problem causing discomfort and distress to many patients in the advanced stages of their disease. It accounts for around 10% of all cases of ascites and occurs in association with a variety of neoplasms, especially breast, bronchus, ovary, stomach, pancreas and colon cancer.² Up to 20% of all patients with malignant ascites have tumours of unknown primary origin.³ Large amounts of ascites can cause increased abdominal pressure with troublesome symptoms like pain, dyspnea, loss of appetite, nausea, reduced mobility and problems with the body image.

Pathophysiology of malignant ascites is multifactorial and is as yet incompletely understood.⁴ Ascites may result from obstruction of lymphatic drainage by tumour cells that prevent absorption of intraperitoneal fluid and protein,⁵ as seen often in lymphomas and breast cancer.⁶ Since the ascites of many patients with malignant ascites has a high protein content, alteration in vascular permeability has been implicated in the pathogenesis of ascites production.⁷ Hormonal mechanisms are also involved. Due to decreased removal of fluid as a consequence of obstructed lymphatics, the circulating blood volume is reduced and this activates the renin–angiotensin–aldosterone system, leading to sodium retention. Therefore reduced sodium intake together with diuretics is often used to treat malignant ascites, but there is no consensus on effectiveness.⁸ A survey by Lee and colleagues showed that paracentesis and diuretics are the most commonly used procedures in management of malignant ascites followed by peritoneovenous shunts, diet measures and other modalities like systemic or intraperitoneal chemotherapy.⁸ In contrast to the treatment of underlying cancer, there is no generally accepted evidence-based guideline for the management of malignant ascites so far. Therefore the aim of this paper is to collect, critically appraise and summarize the evidence on the effectiveness of abdominal paracentesis, diuretics and peritoneovenous shunting in management of malignant asictes and to develop a guideline in order to get evidence to practice.