Gastric Cancer

Essentials

• The most common symptoms are upper abdominal complaints, anaemia and weight loss, but in the majority of cases gastric cancer is asymptomatic in its early stages.
• Gastroscopy is the investigation of choice.
• Surgical resection with adjuvant chemotherapy has improved prognosis.

Frequency

• Gastric cancer is the sixth most common cancer worldwide and the fourth most common cause of cancer death http://www.who.int/news-room/fact-sheets/detail/cancer.
• The incidence of gastric cancer has declined over the last few decades. However, the proportion of gastric cardia carcinomas has increased.
• Geographic variation exists in the incidence of gastric cancer, the rates being highest in Asia, Southern and Eastern Europe and parts of South America and lowest in North America, Northern Europe and Africa. Worldwide, there were almost 970 000 new cases in 2022, with about 660 000 deaths http://gco.iarc.who.int/media/globocan/factsheets/cancers/7-stomach-fact-sheet.pdf.

Aetiology

• Environmental factors are thought to play a central role in the development of gastric cancer. Helicobacter pylori infection is the most important environmental factor.
• Infection by Helicobacter causes inflammation of the gastric mucosa which, in some patients, results in chronic atrophic gastritis. Atrophic mucosa is more likely to undergo changes that lead to cancer.
• Gastro-oesophageal reflux disease Gastro-Oesophageal Reflux Disease and Barrett's oesophagus are often present in gastric cardia carcinomas.
• Smoking and excessive salt intake increase the risk of gastric cancer.
• Consumption of fresh vegetables and fruits decreases the risk of gastric cancer.
• Hereditary factors (CDH1 mutation)

Histology

• Over 90% of cases are adenocarcinomas
  • Intestinal carcinoma
    • This type is the end-result of a carcinogenic cascade, i.e. cancer develops slowly through precursor stages.
    • More common among elderly patients.
    • Spreads by forming distinct tumours.
    • Typically spreads to the lymph nodes and, haematogenously, to the liver.
    • Expression and amplification of the HER2 cancer gene is encountered in about 20% of patients (influences the choice of treatment in advanced disease).
  • Diffuse carcinoma
    • No clearly defined precursor stages.
    • More common in younger patients and in some of them familially.
    • Spreads by infiltration.
    • Typically spreads to the lymph nodes and the peritoneal space.
• Rare tumour types include neuroendocrine carcinomas Rare Endocrine Tumours, lymphomas and GIST tumours http://www.orpha.net/en/disease/detail/44890.

Symptoms

• A major share of gastric cancers are asymptomatic in the early stages.Diagnostic Value of Alarm Symptoms for Upper Gastrointestinal Malignancy
• Alarming symptoms
  • Severe, continuous abdominal pain
  • Weight loss > 3 kg in 6 months
  • Dysphagia
  • Unexplained nausea and vomiting
  • Haematemesis
  • Melaena
• Early satiety during meals is also a possible symptom.

Findings

• Clinical findings are usually only present in advanced disease.
• Alarming findings
  • Anaemia
  • Upper abdominal mass
• Other possible findings
  • Ovarian tumour (metastasis)
  • Ascites
  • A palpable lymph node in the clavicular fossa

Diagnosis and staging

• Gastroscopy and biopsies
  • Should always be carried out if the patient has alarming symptoms Dyspepsia, and in patients over 55 years presenting with a new upper abdominal complaint
• Staging is based on a whole body CT scan (and endoscopic ultrasound)
• The findings of an upper abdominal ultrasound that was prompted by symptoms may potentially include ascites or liver metastasis.
• No specific laboratory tests are available. It is recommended that basic blood count with platelets and liver function tests (ALT, ALP) are checked.

Treatment

Prognosis

• About 50% of gastric cancers are not diagnosed until the disease has advanced, and prognosis is therefore poor.
• The 5-year survival rate is generally about 30% and after curative treatment 50%.

Follow-up

• Intensive follow-up regimens have not been shown to improve prognosis.
• A follow-up regimen aims to
  • detect possible nutritional deficits resulting from the surgery
    • Weight, bowel function, basic blood count with platelets, electrolytes, creatinine, vitamin B₁₂ annually
    • As necessary, the patient should be referred to the care of a dietitian or a specialist physician.
  • identify recurrences which may be treated curatively (rarely).
    • Endoscopy after subtotal gastrectomy every couple of years
    • Imaging studies or a referral for specialist care as guided by symptoms, for example, the emergence of eating difficulties, weight loss or abdominal pain.
• Need for replacement therapy
  • Iron deficiency is the most common cause of anaemia after gastric surgery. It can usually be corrected by oral iron products.
  • Megaloblastic anaemia resulting from vitamin B₁₂ deficiency is also common. After total gastrectomy, vitamin B₁₂ is normally administered through injections every 3 months, but also oral B₁₂ substitution can be tried.
  • Also folate deficiency is possible after gastrectomy.
  • The risk of osteoporosis is increased after gastrectomy, and calcium and vitamin D supplementation is therefore recommended.
  • Use of a pancreatic enzyme product can be tried in severe steatorrhoea and weight loss.