Stomach Cancer

Stomach cancer, also known as gastric cancer, originates from the lining of the stomach. Most cases are gastric carcinomas, which include subtypes like gastric adenocarcinomas. Other types, such as lymphomas and mesenchymal tumours, can also develop. Early symptoms often include heartburn, upper abdominal pain, nausea, and loss of appetite. Advanced stages may show weight loss, jaundice, vomiting, difficulty swallowing, and blood in the stool. The cancer frequently metastasizes to the liver, lungs, bones, abdomen lining, and lymph nodes.

Signs and Symptoms

Stomach cancer is often asymptomatic or presents nonspecific symptoms in early stages, thus often diagnosed late. Signs include unexplained nausea, vomiting, diarrhoea, and constipation. Advanced cancer may cause weakness, fatigue, post-meal bloating, severe upper abdominal pain, vomiting blood, and black stools due to bleeding, leading to anaemia. Dysphagia might indicate a tumour in the stomach's cardia or its extension into the oesophagus.

Risk Factors

Stomach cancer is more common in males, potentially due to oestrogen's protective effect in females. Risk factors include:

• Infections: Helicobacter pylori infection is implicated in 65–80% of cases, though only 2% of infected individuals develop cancer. Epstein–Barr virus and AIDS are also associated with increased risk.
• Smoking: Significantly raises the risk, especially in the upper stomach.
• Alcohol: Some studies suggest increased risk with consumption.
• Diet: High intake of fried, smoked, salted foods, red and processed meats, and pickled vegetables increases risk, while fruits, vegetables, and antioxidants lower it.
• Obesity: Linked to gastroesophageal reflux disease (GERD), increasing the risk of gastric adenocarcinoma.

Genetic factors account for about 10% of cases, with hereditary diffuse gastric cancer linked to mutations in the CDH1 gene. Heavy metals like arsenic in groundwater are also a risk.

Diagnosis

Diagnosis involves medical history, physical examination, and possibly laboratory tests. Key diagnostic tools include:

• Gastroscopic exam: Involves a fibre-optic camera to visualise the stomach.
• CT scans: Useful for detecting tissue invasion and lymph node involvement.
• Biopsy: Tissue samples are histologically examined to confirm cancer.

Staging

Staging assesses the cancer's spread and helps determine treatment. Stages range from 0 (limited to the inner lining) to IV (metastasized to other organs). Advanced imaging techniques like CT, PET scans, and endoscopic ultrasound are used for staging.

Treatment

Surgery

Surgery is the primary curative treatment, including gastrectomy and lymphadenectomy. Post-operative complications like dumping syndrome and reflux esophagitis are common but can be mitigated by constructing a stomach substitute.

Chemotherapy

Chemotherapy is often used palliatively to shrink tumours and relieve symptoms. Drugs like fluorouracil, cisplatin, and taxotere are commonly used, though their effectiveness varies.

Targeted Therapy

Targeted therapy with HER2 inhibitors like trastuzumab has shown promise, particularly in cases with HER2 overexpression.

Radiation

Radiation therapy is often an adjunct to chemotherapy and surgery.

Lymphoma

MALT lymphomas often resolve after treating the underlying H. pylori infection.

Prognosis and Epidemiology

The prognosis for stomach cancer is generally poor due to late diagnosis, with a five-year survival rate of less than 10%. Globally, it is the fifth most commonly diagnosed cancer and the third leading cause of cancer death. The incidence is higher in developing countries and more common in men.

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Self-assessment MCQs (single best answer)

Which of the following is the most common type of stomach cancer?

Which infection is implicated in 65-80% of stomach cancer cases?

What is a common early symptom of stomach cancer?

Which dietary habit is associated with an increased risk of stomach cancer?

Which gene mutation is linked to hereditary diffuse gastric cancer?

Which diagnostic tool is essential for visualising the stomach and confirming stomach cancer?

What is the primary curative treatment for stomach cancer?

Which targeted therapy drug has shown promise in cases with _HER2_ overexpression?

What is the five-year survival rate for stomach cancer?

Which of the following is NOT a common symptom of advanced stomach cancer?