GI - Gastric cancer, Esophageal cancer, GIST Flashcards

Question

GIST Investigations

Answer 1

Radiological tests - Endoscopic USG + Fine needle aspiration (FNA): cytology analysis + Immunohistochemistry for KIT mutation is diagnostic - Indicated: Neoadjuvant Imatinib is considered before attempted resection of large, locally advanced lesion (likely to be GIST) - Surgically unresectable disease, only using Imatinib - Metastatic disease, only using Imatinib OGD: - Mass woth smooth margins, normal overlying mucosa, bulging into gastric lumen with/ without obstruction - Biopsy is NOT diagnostic CT/ MRI scan: for staging mass character, extent, any metastasis PET scan: high metabolic area (cannot diagnose, cannot replace CT)

Answer 2

Targeted therapy - Tyrosine kinase inhibitor (TKI): Imatinib/ Sunitinib - Neoadjuvant imatinib: upper GIT or distal rectal GIST; increase resectability - Adjuvant imatinib: high risk relapse/ GIST > 3cm in size - Palliative imatinib: metastatic GIST Surgical resection: - Exploration by laparatomy - Indicated for all GIST ≥ 2 cm - GIST < 1 cm can be follow-up conservatively - No need for LN dissection

Answer 3

SCC or AD - Upper 2/3 SCC - Distal 1/3 AD (Barrett's esophagus) Modes of spread: * Direct spread (e.g. trachea leading to tracheoesophageal fistula) * Lymphatic spread * Hematogenous spread Metastasis to organs including * Lungs * Liver * Bones * Adrenals

Answer 4

Risk factors of squamous cell carcinoma (SCC) - Smoking - Alcoholism - Dietary factors * Restricted diet of salted fish and pickled vegetables * Vegetables and citrus fruit deficiency * Trace elements deficiency (e.g. Selenium) * Fungal contaminants (e.g. Aflatoxin) - Underlying esophageal disease * Achalasia * Caustic (ingestion) strictures e.g. bleach/ acid - History of H&N cancer: high risk of synchronous tumours - Prior radiation due to H&N tumour - Genetic: Peutz-Jegher syndrome, PTEN mutation, Plummer-VInson syndrome - HPV infection Risk factors of adenocarcinoma - Smoking (not alcohol) - Obesity and metabolic syndrome - Family history - Gastroesophageal reflux disease (GERD) and Barrett’s metaplasia - Barrett’s esophagus

Answer 5

Characteristics of esophagus * Esophagus is a muscular tube that is 25 cm in length * Begins at cricoid cartilage (at level C6) to stomach (at level T10) * Upper esophageal sphincter (UES) is formed by cricopharyngeus muscle * Lower esophageal sphincter (LES) is NOT an anatomical sphincter but physiological Histological features of esophagus * Outer longitudinal and inner circular layer * Lined by non-keratinizing stratified squamous epithelium

Answer 6

AJCC/ UICC TNM staging * Tumors involving the EGJ with the tumor epicenter no more than 2 cm into the proximal stomach are staged as esophageal cancer * EGJ tumors with their epicenter located more than 2 cm into the proximal stomach are staged as stomach cancer Siewert classification: Type I = Located between 5 and 1 cm proximal to anatomical Z-line - Adenocarcinoma of distal esophagus/ Barrett's esophagus infiltrating EGJ - Treatment = Transthoracic en bloc esophagectomy + Partial gastrectomy + 2- field lymphadenectomy Type II = Located between 1 cm proximal and 2 cm distal to the anatomical Z-line - True gastic cardia cancer - Treatment = Transabdominal/ Transhiatal resection of the distal esophagus + Total gastrectomy + Lymphadenectomy of the lower mediastinum and the abdominal D2 nodal compartment Type III = Located between 2 and 5 cm distal to anatomical Z-line - Subcardial gastric cancer infiltrates EGJ - Treatment = Transabdominal/ Transhiatal resection of the distal esophagus + Total gastrectomy + Lymphadenectomy of the lower mediastinum and the abdominal D2 nodal compartment

Answer 7

Dysphagia: Mechanical obstruction Odynophagia: late disease, indicate extra-esophageal involvement Reflux: tumour invade nerve plexus, aspiration pneumonia risk Haematemesis/ Melena: bleeding from primary tumour/ erosion into aorta or pulmonary vessels Anaemic symptoms: Pallor, palpitation, dyspnea, fatigue Constitutional symptoms: Anorexia, Unintentional weight loss, lymphadenopathy Locally advanced disease: - Hoarseness: Left RLN invasion - Choking/ Cough/ Fever: Tracheoesophageal fistula and aspiration pneumonia - Horner's syndrome Distant met: - Cough/ Dyspnea/ Hematemesis: Lung - Jaundice/ RUQ pain/ Ascites: Liver - Chronic spinal pain: bone

Answer 8

Biochemical: - CBC with differential - Clotting profile - RFT and electrolyte profile: vomiting, contrast, pre-renal causes of dehydration - LFT: nutritional status, liver met - Lung function test, ECG, ECHO: Cardiopulmonary fitness for surgery Imaging: - CXR: Lung met, pleural effusion, aspiration pneumonia, soft-tissue mass e.g. bronchogenic carcinoma causing dysphagia - Barium swallow: tracheoesophageal fistula, demonstrate proximal dilatation/ mucosal irregularity/ annular constriction OGD with biopsy: - Chromoendoscopy with Lugol’s iodine: Normal squamous epithelium with glycogen will mix with iodine and stained black, dark-brown or green brown; Dysplasia or SCC do not stain - Narrow-band imaging: detailed inspection of vascular and mucosal patterns for prediction of histology - Bronchoscopy: only for TE fistula, upper and middle 1/3 of esophagus T/N staging: - Endoscopic ultrasound +/- LN FNAC: depth of invasion and regional LN spread - CT thorax + abdomen: distinguish T4 lesions M staging: - CT thorax + abdomen - PET-CT scan - Laparoscopy

Answer 9

Medical: - Radical radiotherapy - Neoadjuvant chemotherapy and adjuvant chemoradiation Surgical: - Endoscopic mucosal resection (EMR): Snare resection of dysplastic lesion - Endoscopic submucosal dissection (ESD): Dissect lesions from the submucosa - Indication: Dysplasia (Tis) or Superficial cancer that are limited to mucosa (T1a) Surgery: - Trans-thoracic: Lewis-Tanner (2 stage) or McKeown (3-stage) - Transhiatal approach - Lymphnode dissection: Field 1 Cervical, Field 2 Mediastinal, Field 3 abdominal - Indication: T1b or above, resectable disease

Answer 10

Transthroacic approach 1. Lewis-Tanner/ Ivor-Lewis (2-stage: - Stomach is mobilized through a midline abdominal incision to attain tension free and well-vascularized portion for transpition, cardia and upper lesser curvature with left gastric artery and LN resection - Right thoracotomy above 5th rib to access esophagus for Esophagectomy and esophago-gastric anastomosis 2. McKeown: - Stomach is mobilized through a midline abdominal incision to attain tension free and well-vascularized portion for transpition, cardia and upper lesser curvature with left gastric artery and LN resection - Right thoracotomy above 5th rib to access esophagus for Esophagectomy - Neck incision is performed for Cervical esophagogastric anastomosis Transhiatal/ Blunt esophagectomy/ Esophagectomy without throacotomy: - Stomach is mobilized through a midline abdominal incision - Diaphragm is opened from the abdomen and posterior mediastinum is entered - Lower esophagus and tumour is mobilized under direct vision and upper esophagus is mobilized by blunt dissection - Esophagectomy is performed and translocation of stomach to perform a cervical esophagogastric anastomosis through a neck incision - DOES NOT remove LN in upper or middle mediastinum

Answer 11

Transthoracic: 1. Lewis-Tanner: Most common - tumour in distal 1/3 of esophagus or intraabdominal region - Anastomosis is inside the intrathoracic cavity; thus anastomotic leakage can be detrimental, causing mediastinitis or pleuritis 2. McKeown - More appropriate for more proximal tumour, also suitable for distal 1/3 esophagus - Anastomosis is inside the cervical region - Complication like anastomotic leakage is easier to be managed by percutaneous drainage Transhiatal: - Unsuitable for most CA esophagus since complete mediastinal lymphadenectomy cannot be achieved - Thoracotomy is NOT required which is associated with fewer pulmonary complications - Indicated for other diseases e.g. refractory late stage achalasia, caustic agent ingestion

Answer 12

Different fields of dissection - Field 1 = Cervical LN - Field 2 = Mediastinal LN - Field 3 = Intra-abdominal (celiac) LN Standard two-field dissection for majority of tumours - Upper 1/3 (e.g. SCC) = Field 1 and 2 dissection - Lower 1/3 (e.g. AD) = Field 2 and 3 dissection Radical 3-field dissection: - Indicated for extensive SCC that emcompass upper and middle thirds of esophagus

Answer 13

Pulmonary complications * Atelectasis * Pneumonia * Bronchospasm * Acute respiratory distress syndrome (ARDS) * Acute exacerbation of COPD * Pulmonary embolism * Respiratory failure Cardiac complications * Atrial fibrillation (AF) * Myocardial infarction

Answer 14

Conduit complications - Anastomotic leak: Manage by NPO for 5-7 days, PEJ tube feeding from Day 2, Gastrograffin swallow to check leak at Day 7, Open drainage for cervical anastomosis - Anastomotic stricture - Conduit ischemia Chylothorax: - Puncture of thoracic duct - Presence of triglycerides > 110 mg/dL or chylomicrons in pleural fluid - Close monitoring of chest tube output, change to MCT or SCFA nutrition, rehydration, avoid LCFA in diet - Right thoracotomy with retraction of conduit and ligation of thoracic duct RLN injury: hoarseness and aspiration pneumonia Functional disorders: - GERD, Dysphagia, Delayed gastric emptying

Answer 15

Indications * Patients with metastatic cancer * Cancers invading adjacent organs that is unresectable (T4b) Options of palliative treatment * Esophageal dilation with stenting: NOT suitable for tumours long in size due to poor functional peristalsis or located in cervical esophagus due to discomfort * Endoluminal laser technique: restore lumen patency * Radiotherapy: external beam irradiation or brachytherapy; indicated for SCC (radiosensitive) or palliation of EGJ cancers to avoid stenting and subsequent reflux * Chemotherapy: 5-FU and Cisplatin based * Nutritional support: Percutaneous endoscopic gastrostomy (PEG) or jejunostomy tube (PEJ)