Gastric-Cancer.pptx learn to frees with me

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1. Gastric Cancer: Epidemiology, Pathogenesis, Clinical Features, Diagnosis & Management A Structured Overview for Medical Students

2. Introduction to Gastric Cancer Gastric cancer refers to a malignant tumour arising from the stomach, with adenocarcinoma accounting for over 90% of cases. It represents a significant global health challenge, particularly prevalent in regions such as Asia, Eastern Europe, and South America. The disease's insidious nature often leads to delayed diagnosis, as early symptoms are vague and non-specific, consequently resulting in a poor prognosis for many patients. Global Health Burden High incidence in specific geographic areas, contributing to significant morbidity and mortality. Late Diagnosis Subtle early symptoms often lead to presentation at advanced stages, complicating treatment. Poor Prognosis The late stage at diagnosis significantly impacts survival rates and treatment efficacy.

3. Epidemiology: A Global Perspective Gastric cancer ranks as the 5th most common cancer worldwide and is the 4th leading cause of cancer-related mortality. Its incidence varies globally, with notably high rates observed in East Asian countries like Japan, South Korea, and China, as well as in Chile and Eastern European nations. The disease typically affects individuals in their 50s to 70s, with a clear male predominance, exhibiting a male-to-female ratio of approximately 2:1. Comparative incidence rates per 100,000 population across selected regions, highlighting the high burden in East Asia and parts of South America/Eastern Europe. Key Statistics 5th most common cancer worldwide. 4th leading cause of cancer mortality. Peak age: 50-70 years . Male : Female ratio: ≈ 2:1 .

4. Risk Factors: Understanding the Aetiology Gastric cancer development is influenced by a complex interplay of environmental, infectious, genetic, medical, and lifestyle factors. Identifying these risk factors is crucial for prevention and early intervention strategies. Environmental & Dietary High salt intake Smoked and pickled foods Nitrates/Nitrosamines Infectious Agents Helicobacter pylori (major causative agent) Epstein-Barr Virus (EBV) Genetic Predisposition Family history of gastric cancer Hereditary diffuse gastric cancer (CDH1 mutation) Lifestyle Factors Smoking Excessive alcohol consumption Obesity

5. Pathogenesis: The Cancer Cascade The development of gastric cancer is a multi-step process often initiated by chronic inflammation. The Correa cascade illustrates the progression from chronic gastritis to carcinoma. Genetic alterations and inflammatory mediators play pivotal roles in this transformation. Dysplasia → Carcinoma Atrophy & IM Chronic Gastritis H. pylori Infection Key Molecular Events Genetic Alterations: Mutations in tumour suppressor genes like TP53, E-cadherin (CDH1), and amplification of oncogenes such as HER2 are frequently observed. Inflammatory Mediators: Chronic infection and inflammation induce the release of cytokines (e.g., IL-1β, TNF-α), which promote cellular proliferation, angiogenesis, and inhibit apoptosis, thereby facilitating carcinogenesis.

6. Classification: Histological & Anatomical Types Gastric cancer is broadly classified based on its histological characteristics and anatomical location, which guides treatment decisions and prognosis. Early detection of gastric cancer (EGC) is critical, as it is confined to the mucosa or submucosa, regardless of lymph node involvement, and carries a significantly better prognosis than advanced gastric cancer (AGC). Histological Types Intestinal Type Well-differentiated, gland-forming. Strongly associated with H. pylori infection and often occurs in older patients. Diffuse Type Poorly cohesive cells, often with signet-ring morphology. Characterised by linitis plastica (thickening of stomach wall) and is more common in younger patients and women. Anatomical Location Cardia Cancer Located at the gastroesophageal junction. Non-Cardia Cancer Involves the distal stomach (antrum, body). Depth of Invasion Early Gastric Cancer (EGC): Confined to the mucosa or submucosa. Advanced Gastric Cancer (AGC): Invades beyond the submucosa.

7. Gross Morphology: Visualising the Tumour The macroscopic appearance of gastric cancer can vary significantly, reflecting its growth pattern and invasiveness. These morphological forms are often identified during endoscopic examination or surgical resection. Polypoid/Fungating Mass Exophytic growth, projecting into the lumen. Often associated with intestinal-type adenocarcinoma. Ulcerative Lesion Characterised by a central ulceration with raised, indurated margins. Can be confused with benign gastric ulcers. Diffusely Infiltrative Also known as linitis plastica, where the tumour infiltrates the stomach wall without forming a distinct mass, leading to a rigid, thickened stomach. Typically diffuse-type adenocarcinoma.

8. Clinical Features: Presenting Symptoms The clinical presentation of gastric cancer is notoriously non-specific in its early stages, making timely diagnosis challenging. Symptoms typically become more pronounced as the disease progresses to advanced stages. Early Gastric Cancer Often asymptomatic Non-specific dyspepsia Mild nausea Occasional anorexia Advanced Gastric Cancer Unexplained weight loss Early satiety (feeling full after small meals) Persistent epigastric pain Vomiting (especially after meals) Anemia due to chronic occult bleeding Palpable epigastric mass (a late sign)

9. Physical Findings: Signs of Metastasis & Paraneoplastic Syndromes Advanced gastric cancer can manifest with specific physical signs, often indicating metastatic spread or paraneoplastic syndromes. Recognising these signs is crucial for accurate staging and management. 1 Virchow’s Node Enlarged, firm left supraclavicular lymph node, indicating metastasis from abdominal malignancy. 2 Sister Mary Joseph Nodule Umbilical metastasis, appearing as a firm, palpable nodule at the umbilicus. 3 Krukenberg Tumour Ovarian metastasis, typically bilateral and often associated with signet-ring cell histology. 4 Blumer’s Shelf Rectal shelf metastasis, palpable on digital rectal examination, representing peritoneal dissemination. 5 Paraneoplastic Syndromes Acanthosis Nigricans (darkening and thickening of skin) Leser–Trélat sign (sudden eruption of multiple seborrheic keratoses)

10. Diagnosis: Unveiling the Tumour The accurate diagnosis and staging of gastric cancer are paramount for determining the most appropriate treatment strategy. A combination of endoscopic, imaging, and pathological assessments is typically employed. 01 Endoscopy with Biopsy The gold standard for diagnosis, allowing direct visualisation of the gastric mucosa and histological confirmation through biopsy. 02 Endoscopic Ultrasound (EUS) Provides detailed imaging of the gastric wall layers to assess the depth of tumour invasion (T stage) and regional lymph node involvement. 03 CT/MRI/PET Scans Crucial for comprehensive staging, detecting distant metastases, and evaluating lymph node involvement beyond the immediate vicinity. 04 Tumour Markers CEA, CA 19-9, CA 72-4 can be elevated but are non-specific for gastric cancer and mainly used for monitoring treatment response and recurrence. Note on Barium Meal While historically used, barium meal studies have largely been replaced by endoscopy due to its superior diagnostic accuracy and ability to obtain tissue biopsies.