Carcinoma Stomach | Medical Science Optional Notes for UPSC PDF Download

Etiology

• External Risk Factors:
  • Consumption of diets high in nitrates and salts (e.g., preserved or dried foods).
  • Usage of nicotine.
  • Lower socioeconomic status.
• Internal Risk Factors:
  • Medical conditions linked to an elevated risk of gastric cancer.
  • Atrophic gastritis.
  • Presence of H. pylori infection: connected to a higher likelihood of intestinal gastric cancer, not diffuse gastric cancer.
  • Occurrence of gastric ulcers.
  • Past partial gastrectomy.
  • Gastroesophageal reflux disease (GERD), especially concerning cancers affecting the gastroesophageal junction.
  • Presence of adenomatous gastric polyps.
  • Hereditary factors like a positive family history or hereditary non-polyposis colorectal cancer.
  • Increased incidence among individuals with blood type A.

Pathology

• Adenocarcinoma (found in 90% of cases):
  • Typically presents as a localized, outward-growing lesion, possibly with ulceration.
  • Originates from glandular cells within the stomach, often situated on the stomach's lesser curvature.
• Lauren Classification of Gastric Adenocarcinoma:
  • Intestinal type (approximately 50% of cases): Exhibits a polypoid appearance with glandular formation, characterized by an expanding growth pattern and clear boundaries.
  • Diffuse type (about 40% of cases): Shows infiltrative growth throughout the gastric wall without distinct borders.
  • Mixed type (around 10% of cases).
• Signet Ring Cell Carcinoma:
  • Demonstrates diffuse growth and contains multiple signet ring cells, which are round cells filled with mucin and possess a flat nucleus at the cell periphery.
• Less Common Types:
  • Adenosquamous Carcinoma.
  • Squamous Cell Carcinoma.

Clinical features

• Gastric cancer often lacks noticeable symptoms in its early stages, with initial signs being nonspecific and easily overlooked.
• As the disease progresses, the following symptoms may manifest:
  • General indications such as weight loss and chronic iron deficiency anemia, characterized by paleness, fatigue, and headaches.
  • Gastrointestinal signs including abdominal pain, early feeling of fullness, nausea or vomiting, difficulty swallowing (dysphagia), and acute gastric bleeding leading to hematemesis (vomiting blood) or melena (black, tarry stools).
• In later stages of gastric cancer, additional symptoms may arise:
  • Detection of a palpable tumor in the epigastric region.
  • Gastric outlet obstruction.
  • Physical manifestations like hepatomegaly (enlarged liver) and ascites (abdominal fluid accumulation).
  • Identification of Virchow's node, an adenopathy in the left supraclavicular area, located at the junction of the thoracic duct and subclavian vein.
  • Sister Mary Joseph's node, indicating umbilical metastasis from a gastrointestinal or abdominopelvic malignancy.
  • Malignant acanthosis nigricans, particularly associated with gastric adenocarcinoma.

Metastasis

• Lymphangitic Spread:
  • Extends to various local lymph nodes including those along the lesser and greater curvature of the stomach.
  • Spreads to distant locations such as celiac, paraaortic, and mesenteric lymph nodes.
  • Carcinoma located at the cardia region might disseminate to mediastinal lymph nodes.
• Hematogenous Spread:
  • Involves metastasis to organs like the liver, lungs, skeletal system, and brain.
• Local Invasion of Adjacent Structures:
  • Manifests as peritoneal carcinomatosis and invasions into neighboring organs such as the esophagus, transverse colon, pancreas, etc.
• Direct Seeding: Metastasizes directly to specific areas:
  • Ovaries, forming Krukenberg tumors which are ovarian malignancies mainly comprised of signet ring cells originating primarily from the stomach.
  • Pouch of Douglas, a space in the pelvic cavity between the rectum and uterus, can also be a site of direct seeding.

Diagnosis

• Upper Endoscopy with Biopsy (preferred initial test): Biopsy confirms the diagnosis.
• Barium Upper GI Series might be considered and would display the loss of intestinal folds and stenosis.
• Laboratory Tests: Evaluation for iron deficiency anemia and serologic markers, potentially TNF-a as a future tumor marker.
• Staging Methods:
  • Abdominal ultrasound.
  • Endosonography for assessing tumor depth and local lymph nodes.
  • Abdominal and pelvic CT-scan using both intravenous and oral contrast.
  • Thoracic CT-scan.
  • Diagnostic laparoscopy.

Staging

• T1: The tumor involves either the lamina propria (T1a) or the submucosa (T1b).
• T2: The tumor invades the muscularis propria.
• T3: The tumor extends to the subserosa.
• T4a: The tumor perforates the serosa.
• T4b: The tumor invades nearby organs.
• N0: No involvement of lymph nodes.
• N1: Presence of metastasis in 1-2 regional nodes.
• N2: Presence of metastasis in 3-6 regional nodes.
• N3a: Presence of metastasis in 7-15 regional nodes.
• N3b: Presence of metastasis in more than 15 regional nodes.
• M0: No distant metastasis.
• M1: Distant metastasis, which includes peritoneum and distant lymph nodes.

Management algorithm

Treatment

Roux-en-Y

Chemotherapy 

• Combination therapy-Epirubacin, cis- platinum and infusional 5-FU or an oral anlogue such as capecitabine
• Herceptin (Transtuzumab) in HER2- positive gastric cancer 

Radiotherapy 

• Palliative therapy of painful bony metastasis

Repeats

Q: Briefly enumerate the various differential diagnoses in a patient presenting with gastric outlet obstruction. How will you assess and manage such a patient due to gastric carcinoma in pyloric area? (2012)