Evaluation and treatment of malignant ascites secondary to gastric cancer

Abstract

Malignant ascites affects approximately 10% of patients with gastric cancer (GC), and poses significant difficulties for both patients and clinicians. In addition to the dismal general condition of affected patients and the diversity of associated complications such as jaundice and ileus, problems in assessing scattered tumors have hampered the expansion of clinical trials for this condition. However, the accumulation of reported studies is starting to indicate that the weak response to treatment in GC patients with malignant ascites is more relevant to their poor prognosis rather than to the ascites volume at diagnosis. Therefore, precise assessment of initial state of ascites, repetitive evaluation of treatment efficacy, selection of suitable treatment, and swift transition to other treatment options as needed are paramount to maximizing patient benefit. Accurately determining ascites volume is the crucial first step in clinically treating a patient with malignant ascites. Ultrasonography is commonly used to identify the existence of ascites, and several methods have been proposed to estimate ascites volume. Reportedly, the sum of the depth of ascites at five points (named "five-point method") on three panels of computed tomography images is well correlated to the actual ascites volume and/or abdominal girth. This method is already suited to repetitive assessment due to its convenience compared to the conventional volume rendering method. Meanwhile, a new concept, "Clinical Benefit Response in GC (CBR-GC)", was recently introduced to measure the efficacy of chemotherapy for malignant ascites of GC. CBR-GC is a simple and reliable patient-oriented evaluation system based on changes in performance status and ascites, and is expected to become an important clinical endpoint in future clinical trials. The principal of treatment for GC patients with ascites is palliation and prevention of ascites-related symptoms. The treatment options are various, including a standard treatment based on the available guidelines, cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC), laparoscopic HIPEC alone, intravenous chemotherapy, intraperitoneal chemotherapy, and molecular targeting therapy. Although each treatment option is valid, further research is imperative to establish the optimal choice for each patient.

Keywords: Ascites; Clinical benefit; Gastric cancer; Paclitaxel; Peritoneal dissemination.

Figure 1

Five-point method to measure ascites volume. Upper: Line between the bilateral antero-posterior mid-points of the abdominal wall is drawn at the plane of the root of the superior mesenteric artery. The distances between the inner surface of the right abdominal wall and the liver (A cm), and between the inner surface of the left abdominal wall and spleen (B cm) are obtained. When spleen is not observed on this plane, the distance between the left abdominal wall and margin to the ascites and internal organs are measured (B’ cm); Middle: The lower pole of the left kidney is observed on this plane. The sagittal line from the bilateral paracolic gutter, and between the bilateral antero-posterior midpoints of the abdominal wall is drawn. The distances C (cm) and D (cm) are thus obtained. Lower: A line between the anterior sides of the bilateral femoral artery is drawn. The distance between the inner surface of the abdomen (at the middle) and the line is obtained (E cm). The ascites volume is calculated by the equation of (A + B + C + D + E) × 200 (mL).

Figure 2

Clinical benefit response in gastric cancer. CBR-GC is defined by the ascites response to treatment (horizontal axis) and ECOG-PS (vertical axis). Response of ascites is judged by a combination of abdominal girth and treatment intensity. CBR-GC: Clinical benefit response in gastric cancer; ECOG-PS: Eastern Cooperative Oncology Group performance status.