Discussion

Gastric carcinoma is the fourth most common carcinoma and the second leading cause of cancer-related deaths. Two-thirds of cases occur in developing countries with most incidences recorded in Japan and South Korea. Incidence peaks at 50–70 years old with male to female ratio of 2:1⁽¹⁾. Risk factors for gastric carcinoma are multifactorial, involving both inherited and environmental factors such as diet (high intake of red meat, salted and smoked food), smoking and Helicobacter pylori infections⁽²⁾. Pathologically, 90% of stomach cancers are adenocarcinomas⁽¹⁾.

The lack of early pathognomonic symptoms often delays the diagnosis. Consequently, 80% to 90% of patients with gastric cancer present with locally advanced or metastatic tumors that have poor rates of resectability. Nausea, vomiting and early satiety may occur with bulky tumors that obstruct the gastrointestinal lumen or infiltrative lesions that impair stomach distension, such as in our case. Ulcerated tumors may cause bleeding that manifests as hematemesis, melena, or massive upper gastrointestinal hemorrhage⁽³⁾. Ultrasonography, CT scan and esophagogastroduodenoscopy are important tools for gastric carcinoma assessment. There is no specific tumor marker for gastric carcinoma.

Ultrasonography is often the first imaging modality used for the assessment of palpable abdominal masses. In addition to identifying portal vein thrombosis, the Doppler mode is also useful in identifying the nature of the thrombus. The presence of florid Doppler signals within the filing defect would confirm that it is comprised of soft tissue rather than blood clot. This is particularly important in district settings where CT scan may not be immediately accessible for further characterization of the thrombus. This finding will facilitate further workup and treatment for invasive periportal malignancy rather than medical causes of portal vein thrombosis.

Accurate identification and diagnosis of portal vein tumor thrombus (PVTT) against non-neoplastic thrombosis are particularly important in advanced hepatocellular carcinoma as the presence of PVTT carries a significantly poorer prognosis. On the other hand, there is scarcity of data on PVTT due to other cancers. According to pathological autopsies from Japan, PVTT originating from gastric cancer is rare and reported to account for merely 1.2%⁽⁴⁾.

PVTT from gastric carcinoma also carries a grim prognosis with median survival of 5.4 months. Some significant risk factors associated with short median survival are older age, female gender and hepatic mass type of PVTT. Definitive management is controversial as surgical resection of the primary tumor, with or without thrombectomy of PVTT, does not seem to contribute to improved survival rates⁽⁴⁾.