Gastric Cancer

Gastric cancer, or stomach cancer, is a malignant tumor that arises from the epithelial lining of the stomach. The majority of cases are adenocarcinomas, originating from the glandular cells of the gastric mucosa. While the disease often progresses insidiously, it can eventually invade adjacent structures or metastasize via lymphatic and hematogenous pathways. Early-stage gastric cancer is often asymptomatic. As the tumor advances, patients may develop nonspecific symptoms such as epigastric discomfort, nausea, early satiety, or dyspepsia.

In more advanced disease, systemic signs such as weight loss, iron-deficiency anemia, gastrointestinal bleeding, or gastric outlet obstruction may become apparent. Accurate diagnosis typically involves upper endoscopy with biopsy, followed by staging workup using imaging modalities such as contrast-enhanced CT and PET-CT. Treatment strategies depend on tumor depth, lymph node involvement, and molecular characteristics, and may include endoscopic submucosal dissection (ESD) for early-stage lesions, gastrectomy with lymphadenectomy, systemic chemotherapy, radiation, and molecularly targeted or immune-based therapies.

The majority of gastric cancers are adenocarcinomas, which originate from the glandular epithelium of the gastric mucosa. Adenocarcinomas are further classified histologically into:

• Intestinal type (Lauren classification): Typically well-differentiated and associated with chronic atrophic gastritis and intestinal metaplasia.
• Diffuse type: Poorly cohesive cells, often including signet-ring cells; associated with worse prognosis and not linked to intestinal metaplasia.

Less common histologic subtypes include:

• Gastrointestinal stromal tumors (GISTs): Mesenchymal tumors arising from the interstitial cells of Cajal. 
• Primary gastric lymphomas: Usually B-cell non-Hodgkin lymphomas, such as MALT lymphoma or diffuse large B-cell lymphoma (DLBCL).
• Neuroendocrine tumors (NETs): Graded according to mitotic count and Ki-67 index, ranging from low-grade NETs to poorly differentiated neuroendocrine carcinomas.

Gastric cancer often does not cause noticeable symptoms in its early stages. As the tumor advances, patients may develop nonspecific symptoms. 

Common symptoms may include:

• Persistent indigestion or heartburn
• Epigastric discomfort or pain
• Nausea or vomiting
• Feeling full after eating only a small amount (early satiety)
• Loss of appetite
• Unexplained weight loss
• Fatigue or weakness
• Black, tarry stools (a sign of gastrointestinal bleeding)
• Vomiting blood

It is important to note that these symptoms can be caused by conditions other than cancer, such as gastritis or ulcers. However, if they persist or worsen over time, medical evaluation is strongly recommended.

Common risk factors include:

• Helicobacter pylori (H. pylori) infection: A chronic infection with H. pylori bacteria is one of the strongest known risk factors. It can lead to long-term inflammation (gastritis) and precancerous changes in the stomach lining.
• Dietary factors: Diets high in salty, smoked, or pickled foods, and low in fruits and vegetables, are associated with higher risk.
• Chronic gastritis or intestinal metaplasia: Persistent inflammation or abnormal transformation of the stomach lining increases cancer risk.
• Genetic syndromes (e.g., hereditary diffuse gastric cancer, Lynch syndrome): Although rare, certain inherited conditions greatly increase the risk of early-onset gastric cancer.

Having one or more risk factors does not mean a person will definitely develop gastric cancer. However, understanding and managing these risks—especially H. pylori infection—can play an important role in prevention and early detection.