Comprehensive Study Notes: Carcinoma of the Stomach (Ca Stomach) Flashcards

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Incidence

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Gastric cancer has the highest incidence in Japan and is more common in Eastern than Western countries. It predominantly affects the elderly, is twice as common in males as females, and is more frequent in low socioeconomic groups.

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Correa Model

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The Correa model describes the stepwise pathogenesis from chronic gastritis to carcinoma: chronic gastritis → gastric atrophy → intestinal metaplasia → dysplasia → carcinoma in situ → invasive cancer. This model emphasizes progressive mucosal changes leading to intestinal-type gastric cancer.

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Dietary Risk Factors

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Dietary nitrates converted by gut bacteria into nitrosamines are potent carcinogens associated with gastric cancer. Other dietary risks include salted, pickled, smoked, spiced or grilled foods, alcohol, protein malnutrition, and deficiencies of vitamins and trace elements.

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H. pylori

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Infection with Helicobacter pylori is classified as a Class I carcinogen and predisposes to chronic atrophic gastritis, intestinal metaplasia, dysplasia, and eventual gastric carcinoma. Eradication can reduce but does not eliminate long-term cancer risk once metaplasia is established.

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Predisposing Conditions

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Conditions that raise gastric cancer risk include autoimmune or atrophic gastritis, pernicious anemia, prior gastric surgery (remnant/stump cancer), large adenomatous polyps (>2 cm), chronic gastric ulcers, EBV infection, and radiation exposure. These conditions promote chronic mucosal damage or metaplasia that can progress to malignancy.

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Lifestyle Factors

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Smoking and alcohol consumption increase gastric cancer risk, and individuals with blood group A show associations with hypoacidity and certain cancer subtypes. Lifestyle modification can reduce some modifiable risks.

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Genetic Factors

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Genetic predisposition includes family history (about 10% familial) and tumor suppressor gene mutations such as $p53$. Some familial syndromes may warrant prophylactic total gastrectomy in high-risk individuals.

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Early Gastric Cancer

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Early gastric cancer is defined as tumor limited to the mucosa and submucosa, with or without lymph node involvement (T1 any N). It has an excellent cure rate (about 95% five-year survival) but may still have nodal metastases in a minority of cases.

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Advanced Gastric Cancer

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Advanced gastric cancer invades the muscularis propria and/or serosa (T2–T4) and is classified macroscopically by systems such as Borrmann. Prognosis is worse and management usually requires more extensive surgery and adjuvant therapies.

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Lauren Classification

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Lauren classification divides gastric adenocarcinoma into intestinal and diffuse types based on histology and behavior. The intestinal type is gland-forming, localized, more common in older males, and has a relatively better prognosis, while the diffuse type shows infiltrative growth, affects younger patients and females, and has a worse prognosis.

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Intestinal Type

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The intestinal type arises from areas of intestinal metaplasia and tends to form discrete glandular masses. It is more common in older males, associated with environmental exposures, and generally has a better prognosis than the diffuse type.

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Diffuse Type

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Diffuse-type gastric cancer is characterized by infiltrative growth of poorly cohesive cells, often including signet-ring cells, and can cause linitis plastica (leather-bottle stomach). It affects younger patients, shows stronger genetic associations, and typically has a poorer prognosis.

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Gross Types

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Macroscopic growth patterns include fungating (cauliflower) lesions, ulcerative (raised-everted) lesions, and infiltrative/linitis plastica (leather-bottle) or colloid types. Ulcerative forms are most common, while infiltrative types are associated with obstruction and poorer outcomes.

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WHO Classification

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WHO classification lists major gastric malignancy types such as adenocarcinoma (papillary, tubular, mucinous, signet-ring), adenosquamous, squamous, undifferentiated, and unclassified carcinomas. Histologic subtype guides prognosis and therapy choices.

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Broder's Grading

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Broder's grading categorizes tumor differentiation into grades based on the degree of glandular formation and differentiation. Higher grades indicate poorer differentiation and generally predict worse prognosis.

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Common Sites

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Gastric cancers most commonly occur in the prepyloric and pyloric regions (about 65%), followed by the body (25%) and fundus (10%), and can also involve the oesophagogastric junction or the whole stomach. Tumor site affects surgical approach and symptoms.

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Direct Spread

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Direct spread involves local invasion through the stomach wall to adjacent intra-abdominal organs such as omentum, transverse colon, mesocolon, left liver lobe, and pancreas. Local extension often precedes distant metastasis and influences resectability.

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Lymphatic Spread

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Gastric cancers spread via lymphatics following the vascular supply to regional nodes including coeliac and para-aortic nodes and onward to the cisterna chyli and thoracic duct. Left supraclavicular node enlargement (Virchow’s node) can result from this lymphatic route.

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Virchow Node

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Virchow’s node refers to enlargement of the left supraclavicular lymph node due to metastatic spread through thoracic duct drainage. Its presence (Troisier’s sign) often indicates advanced intra-abdominal malignancy, commonly gastric cancer.

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Hematogenous Spread

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Hematogenous metastases from gastric cancer commonly involve the liver, lungs, bones, and brain, summarized as L L B B. Hematogenous spread typically indicates advanced disease and affects prognosis and systemic treatment decisions.

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Transcoelomic Spread

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Transcoelomic (transperitoneal) spread involves seeding of the peritoneal surfaces, producing findings such as malignant ascites, omental cake, and implants on the pelvic recesses. This route commonly causes peritoneal carcinomatosis and is a poor prognostic sign.

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Krukenberg Tumour

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Krukenberg tumour denotes bilateral mucin-producing metastatic ovarian tumors typically originating from a gastric primary. It reflects transcoelomic or lymphatic spread and often presents with ovarian masses in women with gastric cancer.

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Sister Mary Joseph

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Sister Mary Joseph’s nodule is a firm, often vascular umbilical metastasis from an intra-abdominal malignancy, classically gastric cancer but also colorectal, ovarian, or pancreatic. It indicates advanced disease and may spread via lymphatics, blood, or embryonic ligamentous routes.

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Clinical Features

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Early gastric cancer is often asymptomatic, emphasizing the value of screening, while advanced disease presents variably with lumps, anemia, anorexia, obstruction, new dyspepsia after 40, or signs of metastasis. Examination may reveal palpable masses, supraclavicular nodes, or signs of peritoneal spread.

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LIONS Mnemonic

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The LIONS mnemonic summarizes advanced gastric cancer features: Lump in epigastrium (hard, irregular, fixed), Insidious onset of anemia/anorexia/asthenia, Obstruction (dysphagia or gastric outlet obstruction), New dyspepsia after 40, and Silent presentation with metastases. This aids clinical recognition of advanced disease.

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Complications

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Complications of gastric cancer include bleeding (haematemesis, melaena) and perforation leading to peritonitis. Advanced disease can also cause obstructive symptoms, malnutrition, and paraneoplastic events such as migratory thrombophlebitis (Trousseau’s syndrome).

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Endoscopic Diagnosis

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Upper GI endoscopy (OGD) with biopsy and cytology is the primary diagnostic tool, allowing direct visualization, targeted biopsies for histology, and chromoendoscopy for early lesions amenable to endoscopic resection. Endoscopy provides the definitive tissue diagnosis.

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Barium Meal

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Double-contrast barium meal radiography can characterize polypoid, ulcerative, or infiltrative patterns such as apple-core lesions or linitis plastica. It is useful when endoscopy is not available or as an adjunctive imaging modality.

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Staging Investigations

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Staging uses endoscopic ultrasound (EUS) for T and regional N assessment, CT chest/abdomen for distant metastases, PET for nodal and distant disease evaluation, and diagnostic laparoscopy for intraperitoneal spread. Organ-specific tests (chest X-ray, abdominal ultrasound, brain CT, bone scan) assess the typical metastatic sites.

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TNM T Category

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T staging denotes the depth of primary tumor invasion: T1 limited to mucosa/submucosa, T2 invading muscularis propria, T3 penetrating serosa, and T4 invading adjacent structures outside the stomach. T stage is critical for prognosis and surgical planning.

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TNM N Category

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N staging reflects regional lymph node involvement: N0 no nodes, N1 metastasis in 1–6 regional nodes, N2 in 7–15 nodes, and N3 in more than 15 nodes. The extent of nodal disease guides the extent of lymphadenectomy and indicates prognosis.

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TNM M Category

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M staging indicates distant metastasis: M0 denotes no distant metastases while M1 indicates presence of distant metastatic disease. M1 disease generally renders the condition incurable and directs palliative-directed therapy.

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Curative Surgery

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Curative treatment relies on en bloc resection of the primary tumor with adequate regional lymphadenectomy and restoration of gastrointestinal continuity. The extent (partial, subtotal, total gastrectomy) and lymph node clearance depend on tumor site, depth, and nodal status.

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D1 D2 D3

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D1, D2, and D3 describe progressively extensive lymphadenectomy: D1 removes perigastric (N1) nodes, D2 includes N2 nodes (e.g., along major branches, sometimes with splenectomy or distal pancreatectomy), and D3 extends to N3 nodes and may include adjacent organ resections. Choice of D-level depends on tumor spread and institutional practice.

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Resection Margins

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Resection margins vary by stage: a 2 cm margin is acceptable for early tumors while a 5 cm margin is recommended for advanced tumors to reduce local recurrence. Total gastrectomy is indicated for proximal tumors, diffuse lesions, or multifocal disease.

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Reconstruction

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After distal gastrectomy reconstruction options include Billroth I (gastroduodenostomy), while subtotal or total gastrectomy commonly use Roux-en-Y esophagojejunostomy or gastrojejunostomy. Reconstruction aims to restore bowel continuity and optimize nutrition and quality of life.

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Palliative Treatments

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Palliative options include palliative gastrectomy, gastrojejunostomy bypass, endoscopic stenting (e.g., SEMS) for obstruction, chemotherapy, and radiotherapy for symptom control. Palliative resection often provides better symptom relief than bypass or intubation when feasible.

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Chemotherapy

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Systemic chemotherapy is used in palliative settings and as neoadjuvant or adjuvant therapy; the common ECF regimen includes epirubicin (E), cisplatin (C), and $5$-FU (F). Neoadjuvant chemotherapy has been shown to improve survival in some patients.

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Radiotherapy

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Radiotherapy has a limited role for primary gastric tumors but can effectively palliate painful bone metastases and some local symptoms. It is used selectively alongside systemic therapy in multidisciplinary care.

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Recent Advances

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Recent advances include minimally invasive endoscopic treatments such as endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) for early gastric cancer, and targeted therapies like HER receptor antagonists. Self-expanding metal stents (SEMS) provide endoscopic palliation for obstructing lesions.

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Prognosis

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Prognosis depends on stage: T1 N0 M0 tumors have about 95% five-year survival, whereas M1 disease confers around 10% five-year survival. Early detection and appropriate surgical resection with adequate lymphadenectomy markedly improve outcomes.