CT Gastrography for Staging of Gastric Cancer

Proprietary scanner names: Aquilion 32/64 slice CT System; LightSpeed RT 16; MX 16-slice CT System; SOMATOM Plus 4 CT System Proprietary workstation names: Advantage Workstation 4.1; Infinitt G3; Leonardo Workstation; Vital Image Management System; X-Leonardo Workstation Proprietary software: Accurex, Rapidia; Rex 1.0, Rex 3.0; Vitrea 4.0/VITAL CONNECT; Vitrea 6.0 Enterprise; Voxel Plus 2.0 Generic names: computed tomography (CT) virtual gastrography; three-dimensional multidetector CT gastrography; virtual gastroscopy and multiplanar reconstruction; virtual endoscopy; virtual upper endoscopy; virtual gastrography; virtual upper gastrointestinal endoscopy

Gastric cancer is the general term for malignancies that originate in the stomach. About 90% to 95% of all gastric cancers are adenocarcinomas, which begin in the epithelial cells lining the stomach.1 Other types of gastric cancer include lymphoma, gastrointestinal stromal tumors, and carcinoid tumors.1 Risk factors for gastric cancer include the following:2-4

Early gastric cancer typically produces no signs or symptoms. Early diagnosis improves prognosis.3-5 Signs and symptoms suggestive of advanced gastric cancer include nausea, gastric reflux, abdominal pain, abdominal fluid, swelling, and unexplained weight loss.6 Upper endoscopy with biopsy and histologic examination is required to make a definitive diagnosis.7 After diagnosis, accurate disease staging is critical because appropriate treatment planning depends on the disease stage.8 Clinicians stage gastric cancer using physical examination, laboratory tests, imaging tests (i.e., computed tomography CT, positron-emission tomography PET, magnetic resonance imaging MRI, endoscopic ultrasound), and/or minimally invasive surgery.6,9 The "TNM" staging system, as follows, is the most common method used to stage gastric cancer.10 The system describes the primary tumor's growth into the stomach submucosa or adjacent structures (T), the degree of spread to affected regional lymph nodes (N), and the occurrence of distant metastasis in other organs (M).

Treatment depends on cancer stage. Endoscopic mucosal resection is a treatment option for early gastric cancer when the tumor involves only the mucosa. Treatment for locally advanced malignancies (stage T1, T2, or T3 with little lymph node involvement) may include partial or total gastrectomy and lymph node dissection. Surgery is not recommended for patients with stage T4 tumors (tumors that have grown through the stomach wall into the serosa and may be invading nearby organs or blood vessels).7,11 Palliative treatments for patients with metastatic, inoperable gastric cancer include a combination of endoscopic ablative therapies, stenting, brachytherapy, and external beam radiation therapy.7

Prevalence and incidence of gastric cancer vary considerably among regions of the world. Disease rates are highest in Asia and parts of South America and lowest in North America.11 In the United States, gastric cancer is found slightly more frequently in men than in women.2 The American Cancer Society estimated that clinicians would diagnose 21,130 cases of gastric cancer in the United States in 2009 and that 10,620 patients would die from the disease that year.12 The overall five-year survival rate for gastric cancer patients in the United States is 28%.10 Worldwide, 800,000 new cases of gastric cancer are reported annually; it is twice as...