An adenocarcinoma is the most common type of stomach cancer accounting for over 90% of all malignant stomach tumors. Other rare malignant cancers include leiomyosarcoma, squamous cell carcinoma, and carcinoid tumors. Lymphomas are also seen in stomach.
The gastric cancers can be broadly grouped based on the appearance of the cancer lesion (Borrmann classification). This includes :
- Type I – polypoid or fungating type
- Type II – ulcer type with elevated borders
- Type III – infiltrating ulcer type
- Type IV – diffuse infiltrating type
- Type V – unclassified group
Based on the histology, well differentiated cancers may be grouped as the intestinal type which shows a tendency to form glands and the poorly differentiated cancers as diffuse type. The diffuse type shows widespread thickening of the stomach and can sometimes form a non-distensible stomach known as linitis plastica. The diffuse type is more aggressive and spreads faster than the intestinal type. Younger patients are often affected by the diffuse type and has poor prognosis compared to the intestinal type. The intestinal type is more frequent in older men and it arises from the precancerous conditions like atrophic gastritis. Intestinal type is common in the regions with high incidence of gastric cancer while diffuse type is more common in low-incidence regions. The diffuse type is seen in familial forms of gastric cancer and also associated with the blood group A.
The gastroesophageal junction cancers are of 3 types (Siewert classification). These are :
- Type I
- The tumor arises from the distal end of esophagus and progresses to the gastroesophageal junction below.
- The tumor usually develops following intestinal metaplasia of the lower end of esophagus.
- Barrett’s esophagus is a precancerous condition resulting from chronic GERD characterized by intestinal metaplasia at the lower end of the esophagus.
- Type II
- The tumor arises from the cardiac end or from gastroesophageal junction.
- Type III
- Tumor arises from below the cardiac end of stomach and spread from below to the gastroesophageal junction.
Signs and Symptoms of Gastric Cancer
Early gastric cancer is often asymptomatic or associated with vague symptoms which can delay the diagnosis in many patients. It is often mistaken for other gastrointestinal conditions in these early stages and without proper diagnostic investigation, it can remain undiagnosed until the generalized symptoms associated with cancer prompts further investigation.
Weight loss is one of the most common symptoms associated with later stages of gastric cancer. Other general symptoms include :
- loss of appetite
- epigastric pain, not relieved by antacids, and pain may radiate to the back with pancreas involvement
- difficulty swallowing food (dysphagia)
- generalized abdominal discomfort
A tumor of gastroesophageal junction or in the fundus of stomach is often associated with dysphagia. Tumor of the distal-end may cause partial obstruction to the outflow of gastric contents and can present with persistent vomiting. Vomiting can also be seen in patients with diffuse gastric tumors affecting the effective gastric contractions. A diffuse tumor can also prevent distension the stomach wall, resulting in feeling of fullness of stomach with minimal food (early satiety).
Occasionally some patients can have significant gastrointestinal bleeding which is often associated with vomiting of blood (hematemesis) or black tarry stools (melena) due to passing of the blood into the lower gastrointestinal tract.
Symptoms of Stomach Cancer Spread
Signs of metastasis suggest incurable or an inoperable stage. Gastric cancers that metastasize to liver can cause jaundice or pain over the liver. Sometimes the tumor mass can be felt on examination. Cough, hiccoughs, or coughing up blood (hemoptysis) is seen in patients with gastric cancer that has spread to lungs.
Spread of cancer into the peritoneal cavity can lead to malignant ascites or a malignant mass in the ovary (called Krukenberg’s tumor). Sometimes cancer can spread to the subcutaneous tissue around umbilicus to form a nodular swelling near the umbilicus (called Sister Mary Joseph’s node). Lymphatic spread can result in enlargement of nodes above the clavicle on the left side (called Virchow’s node).