Gastric adenocarcinoma, once a frequent cause of death, is now rarely encountered. It is difficult to cure with patients presenting with advanced disease as initial symptoms are nonspecific and often ignored. Progress is currently being made, after the introduction of radiation therapy and chemotherapy. These protocols are added to the classical surgical intervention, in order to prevent disease relapse and improve survival.
Early stage gastric adenocarcinoma patients have nonspecific symptoms, that usually do not trigger a consultation until the disease has advanced, such as dyspepsia, anorexia, low intensity, diffuse abdominal pain and weight loss [1]. As the disease progresses and the tumor occupies a larger part of the stomach or causes stomach distention, other symptoms, such as early satiety, nausea, vomiting, dysphagia, postprandial fullness appear [2]. With increasing progression, bleeding occurs, and the blood is expelled as hematemesis, melena or hematochezia. With the development of complications, the patient may experience jaundice and peritoneal or pleural effusions, due to metastases or hypoalbuminemia caused by inanition. Pedal edema may also develop due to the same cause [3] [4].
The tumor may cause metastasis in the ovary, the peritoneum or lymph nodes (supraclavicular, left axilla or periumbilical).
Paraneoplastic syndromes, such as acanthosis nigricans and dermatomyositis have been described.
The clinician taking patient history should inquire about previous Helicobacter pylori infection or autoimmune gastritis, knowing that these conditions are predisposing factors for gastric adenocarcinoma.
Workup should begin with a complete blood count, that might show anemia, due to blood loss or insufficient food intake due to lack of appetite. The clinician should also recommend liver function tests (keeping in mind that gastric adenocarcinoma may cause hepatic metastasis) and tumor markers such as carcinoembryonic antigen and cancer antigen 19-9. Even if these antigens are absent, the diagnosis cannot be excluded.
Imaging studies in association with histologic findings confirm or disprove the diagnosis. Upper digestive endoscopy is at this time the gold standard for gastric adenocarcinoma diagnosis [5], as it allows tumor detection and biopsy. Endoscopic methods even allow tumor excision if found in the early stages. Classical endoscopy limitation resides in incomplete staging evaluation, but this can be overcome with endoscopic ultrasonography [6].
Mucosal aspect can also be evaluated using upper gastrointestinal barium study, that involves a lower amount of irradiation than a computer tomogram. The latter can also evaluate invasion of neighboring structures and lymphadenopathy [7]. Liver, bone and peritoneal metastasis are better defined by magnetic resonance, so if symptoms dictate, this should be the method of choice [8]. However, MRI is not as useful in describing gastric lesions per se, because a contrast agent is unavailable [8]. Barium study accuracy can be improved by using double contrast or compressive views.
Once a lesion has been documented, it is important to evaluate the histologic aspect. Adenocarcinomas (tubular, mucinous, papillary, signet-ring cells or undifferentiated) are far more frequent than lymphomas, stromal tumors, carcinoids, adenoacantomas, and squamous cell carcinomas, and account for more than 90% of gastric cancers [9].
Recent studies have described the importance of certain serum glycan patterns as markers for the risk of gastric cancer development [10].