My Clinical Notes

• 90-95% are carcinomas
• The others are;
  • Lymphomas (4%)
  • Carcinoids (3%)
  • Mesenchymal tumours (2%)

                           

Gastric adenocarcinoma

 

• Second most common tumour in the world
• There are countries with particularly high incidence e.g. Japan, China, Costa Rica and Russia
• More common in lower socioeconomic groups
• Male>female 2:1
• Leading cause of cancer death worldwide
• 5 year survival rates are around 20%

 

• Occurs as either intestinal or diffuse types

 

Pathogenesis

• The risk factors for the diffuse type are not well defined
• The risk factors for intestinal type are;
  • Infection with H.pylori
    • Increases risk of developing gastric carcinoma by 5 to 6 times
  • Environmental factors;
    • Diet – lack of refrigeration, use of preservatives, lack of fresh fruit and vegetables
    • Smoking – role is controversial
  • Host factors
    • Autoimmune gastritis – presumably due to chronic inflammation and intestinal metaplasia
    • Genetic factors e.g. HNPCC syndrome and E-cadherin germline mutations
    • Partial gastrectomy allowing for gastrodueodenal reflux

 

Morphology

• The lesser curvature is involved in 40% of cases
• The greater curvature is involved in 12%
• 50-60% of cancers develop in the pylorus and antrum
• 25% in the cardia
• 15-25% in the body and the fundus
• Tumours can be classified based on;
  • Depth of invasion
  • Macroscopic growth pattern
  • Histological subtype

 

Depth of invasion

• The depth of invasion has the greatest impact on clinical outcome
• Early gastric carcinoma is defined as a lesion confined to the mucosa and submucosa regardless of the presence or absence of LN mets
• (in contrast carcinoma in situ is confined to the surface epithelial layer)
• Advanced gastric mucosa is a neoplasm that has extended beyond the submucosa into the muscular wall

 

Macroscopic growth pattern

• There are 3 macroscopic growth patterns that may be evident at both early and advanced stages
• These are;
  • Exophytic – protrusion of the tumour mass into the lumen
  • Flat/depressed – where there is no obvious tumour mass in the lumen
  • Excavated – whereby an erosive crater is present in the wall of the stomach
• Uncommonly a broad region of the gastric wall or entire stomach is extensively infiltrated by malignancy creating a rigid, thickened leather bottle termed LINITIS PLASTICA

 

Histological subtypes – via the Lauren classification

• Intestinal type
  • Gland forming columnar epithelium
  • Usually mucin producing
  • Usually polyploid expansile growth pattern
  • Almost always associated with mucosal intestinal metaplasia
  • Mean age is 55 M>F 2:1
  • Incidence is decreasing
• Diffuse type
  • Poorly differentiated
  • Single signet ring cells
  • Mucin producing
  • Infiltrative growth pattern
  • Mane age is 48 M=F
  • Familial gastric carcinoma is of diffuse type
  • Presence of intestinal metaplasia is not a prerequisite

 

• For some reason gastric carcinoma frequently spreads to the supraclavicular Virchow node
• The tumour can also metastasise to the periumbilical region to for a subcutaneous nodule – called Sister Mary Joseph nodule
• Ovarian involvement generates Krukenberg tumours

 

Clinical

• Generally asymptomatic until late in the course
• Patients present with weight loss, abdo pain, anorexia, vomiting, altered bowel habit, dysphagia, anaemia and haemorrhage
• Prognosis after resection depends on the depth of invasion
• Early gastric carcinoma – 90% 5 year survival rate
• Late gastric carcinoma – 15% 5 year survival rate

 

This entry was posted on Sunday, February 24th, 2008 at 1:57 pm and is filed under Gastrointestinal. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.