Gastric carcinoma

Gastric carcinoma refers to a primary malignancy arising from the gastric epithelium.

Epidemiology

Gastric cancer is rare before the age of 40, but its incidence steadily climbs thereafter and peaks in the seventh decade of life ². The median age at diagnosis for gastric cancer in the United States is 70 years for males and 74 years for females.

Gastric cancer continues to be one of the leading causes of cancer-related death. An important development in the epidemiology of gastric carcinoma has been the recognition of the association with Helicobacter pylori infection. Most gastric cancers occur sporadically, whereas 8  - 10% have an inherited familial component.

Clinical presentation

It often produces no specific symptoms when it is superficial and potentially surgically curable, although up to 50% of patients may have non-specific gastrointestinal complaints such as dyspepsia ².

Patients may present with anorexia and weight loss (95%) as well as abdominal pain that is vague and insidious in nature. Nausea, vomiting, and early satiety may occur with bulky tumors that obstruct the gastrointestinal lumen or infiltrative lesions that impair stomach distension ².

Pathology

Adenocarcinoma is by far the most common gastric malignancy, representing over 95% of malignant tumors of the stomach. The remaining malignant tumours include lymphoma, sarcoma (eg, malignant gastrointestinal stromal tumour), carcinoid tumour, metastasis, and so on ¹.

Radiographic features

Endoscopy is regarded as the most sensitive and specific diagnostic method in patients suspected of harboring gastric cancer. Endoscopy allows direct visualization of tumor location, the extent of mucosal involvement, and biopsy (or cytologic brushings) for tissue diagnosis³. But radiological methods are often the initial examination that raises suspicion for gastric carcinoma, besides being used in the staging of the disease.

Fluoroscopy

Early gastric cancer (elevated, superficial, shallow):

• type I : elevated lesion-protudes > 5 mm into lumen (polypoid).
• type II : superficial lesion (plaque-like, mucosal nodularity, ulceration).
• type III : shallow, irregular ulcer crater with adjacent nodular mucosa & clubbing / fusion / amputation of radiation folds ⁴.

Advanced gastric cancer :

• polypoid cancer can be lobulated or fungating;
• lesion on dependent or posterior wall; filling defect in barium pool.
• lesion on nondependent or anterior wall; etched in white by a thin layer of barium trapped between edge of mass & adjacent mucosa.
• ulcerated carcinoma (penetrating cancer): 70% of all gastric cancers ⁴.

Ultrasound

Not useful, unless a large epigastric mass is present or on endoscopic ultrasound study.

CT

CT is currently the staging modality of choice because it can help identify the primary tumor, assess for local spread, and detect nodal involvement and distant metastases¹.

Demonstration of lesions facilitated by negative contrast agents (water or gas):

• a polypoid mass with or without ulceration;
• focal wall thickening with mucosal irregularity or focal infiltration of wall;
• ulceration: gas-filled ulcer crater within mass;
• infiltrating carcinoma : wall thickening + loss of normal rugal fold pattern ⁴.

Treatment and prognosis

It is an aggressive tumor with a 5-year survival rate of less than 20%. Prognosis is correlated to the stage of the tumor at presentation. Therefore, accurate staging of gastric cancer is essential because surgical resection is the treatment for localized disease¹.

Complications

• perforation with peritonitis : rare (thought to occur ~ 0.4 - 4 of cases ^5-6

Differential diagnosis

The imaging differential can be broad and includes :

• gastric lymphoma
• gastric metastasis
• gastric stromal tumour : GIST
• gastritis
• benign gastric (peptic) ulcer
• Menetrier disease
• secondary changes from pancreatitis (from extrinsic inflammatory change)