Master Sheet: Gastric Cancer and
Helicobacter Pylori
CORE MECHANISMS (Must Memorise)
1. What is Helicobacter Pylori?
Definition: Gram-negative microaerophilic bacterium that colonizes
the human stomach, identified by Warren and Marshall in the early
1980s as responsible for most cases of gastritis and peptic ulcer[1][2].
Epidemiology:
• Worldwide prevalence of H. pylori: 50%[1][2]
• Developing countries: up to 90%[1]
• May play a role in natural gastric ecology[1]
• Blood group A individuals more susceptible (antigen binding)[1]
Morphological forms:
• Spiral form – active colonization[1]
• Coccoid form – viable but non-culturable (VBNC) form[1]
Historical significance: Warren and Marshall received the Nobel
Prize for identifying HP as the causative agent of gastritis and peptic
ulcers[1].
2. Gastric Cancer: A Global Disease
Epidemiology:
• 4th most common malignant disease worldwide (~930,000
cases)[1]
• 2nd most common cause of cancer-related death worldwide
(~700,000 deaths)[1]
• Falling incidence of distal gastric cancer[1]
, • Increasing incidence of proximal gastric cancer[1]
• Wide geographical variation (high in Asia, parts of Europe)[1]
Declining trends attributed to:
• Identification of risk factors (HP infection)[1]
• Treatment of HP infection[1]
• Better screening for earlier lesions[1]
• Improved monitoring and surgical intervention[1]
3. Stomach Anatomy and Defense Mechanisms
Anatomical regions and functions:
Region Function
Fundus/Cardia Mucus-secreting cells (protective mucus layer)[1]
Parietal cells (secrete acid and intrinsic factor for
Body vitamin B12 absorption); Chief cells (secrete
pepsinogen → pepsin)[1]
Cells that secrete gastrin hormone[1]; Site of most
Antrum
HP damage[1]
Pyloric canal Connects stomach to duodenum
Table 1: Gastric anatomy and cellular functions
Defense mechanisms:
• Mucus layer coats and protects epithelial cells from acid
content[1]
• Gastric acidity enhances pepsin activity and protects from
pathogens[1]
• Gastrin increases acid release through feedback regulation[1]
Histological layers:
• Mucosa (surface epithelium, lamina propria, muscularis
mucosae)[1]
• Submucosa
• Muscularis externa (oblique, circular, longitudinal layers)
• Serosa
, 4. HP Survival Strategy and Colonization
Survival mechanisms:
1. Migration: Move to regions with less acidic pH using flagella for
mobility and chemotaxis[1][2]
2. Neutralization: Release urease enzyme to convert urea into
ammonia, neutralizing gastric acid and allowing colonization[1]
[2]
3. Adherence: Bind to gastric mucosa via:
• Lipoprotein A-B
• Group antigen binding protein (blood group A more
susceptible)[1]
• OipA (outer inflammatory protein)
Detection methods:
• Immunohistochemistry on gastric biopsy[1]
• Bacterial DNA detection in fecal samples[1]
• Endoscopic biopsy with histology
5. Virulence Factors of HP
Helicobacter Pylori
CORE MECHANISMS (Must Memorise)
1. What is Helicobacter Pylori?
Definition: Gram-negative microaerophilic bacterium that colonizes
the human stomach, identified by Warren and Marshall in the early
1980s as responsible for most cases of gastritis and peptic ulcer[1][2].
Epidemiology:
• Worldwide prevalence of H. pylori: 50%[1][2]
• Developing countries: up to 90%[1]
• May play a role in natural gastric ecology[1]
• Blood group A individuals more susceptible (antigen binding)[1]
Morphological forms:
• Spiral form – active colonization[1]
• Coccoid form – viable but non-culturable (VBNC) form[1]
Historical significance: Warren and Marshall received the Nobel
Prize for identifying HP as the causative agent of gastritis and peptic
ulcers[1].
2. Gastric Cancer: A Global Disease
Epidemiology:
• 4th most common malignant disease worldwide (~930,000
cases)[1]
• 2nd most common cause of cancer-related death worldwide
(~700,000 deaths)[1]
• Falling incidence of distal gastric cancer[1]
, • Increasing incidence of proximal gastric cancer[1]
• Wide geographical variation (high in Asia, parts of Europe)[1]
Declining trends attributed to:
• Identification of risk factors (HP infection)[1]
• Treatment of HP infection[1]
• Better screening for earlier lesions[1]
• Improved monitoring and surgical intervention[1]
3. Stomach Anatomy and Defense Mechanisms
Anatomical regions and functions:
Region Function
Fundus/Cardia Mucus-secreting cells (protective mucus layer)[1]
Parietal cells (secrete acid and intrinsic factor for
Body vitamin B12 absorption); Chief cells (secrete
pepsinogen → pepsin)[1]
Cells that secrete gastrin hormone[1]; Site of most
Antrum
HP damage[1]
Pyloric canal Connects stomach to duodenum
Table 1: Gastric anatomy and cellular functions
Defense mechanisms:
• Mucus layer coats and protects epithelial cells from acid
content[1]
• Gastric acidity enhances pepsin activity and protects from
pathogens[1]
• Gastrin increases acid release through feedback regulation[1]
Histological layers:
• Mucosa (surface epithelium, lamina propria, muscularis
mucosae)[1]
• Submucosa
• Muscularis externa (oblique, circular, longitudinal layers)
• Serosa
, 4. HP Survival Strategy and Colonization
Survival mechanisms:
1. Migration: Move to regions with less acidic pH using flagella for
mobility and chemotaxis[1][2]
2. Neutralization: Release urease enzyme to convert urea into
ammonia, neutralizing gastric acid and allowing colonization[1]
[2]
3. Adherence: Bind to gastric mucosa via:
• Lipoprotein A-B
• Group antigen binding protein (blood group A more
susceptible)[1]
• OipA (outer inflammatory protein)
Detection methods:
• Immunohistochemistry on gastric biopsy[1]
• Bacterial DNA detection in fecal samples[1]
• Endoscopic biopsy with histology
5. Virulence Factors of HP
