GASTRIC CA Dr. Wenceslao | Sept. 20, 2021 Gen Data: 68/Male CC: Epigastric pain Impression: Gastric outlet obstruction secondary to adenocarcinoma Differential diagnosis: 1. Adenocarcinoma- most common GI malignancy 2. Gastric outlet obstruction – secondary to edema, scar formation, decompression; in most cases, it is secondary to malignancy Physical findings in malignancy - Check for lymphadenopathy o Periumbilical (Sister Mary Joseph nodule) o Virchow’s node - Succussion splash? During auscultation EGD – to confirm gastric outlet obstruction If EGD is not available, Saline Load Test (NaCl test) – traditional Do BIOPSY ANCILLARY EXAMINATION 1. CBC – check for anemia 2. Fluid electrolytes (gastric obstruction) o Hypokalemic, hypochloremic o A normal electrolyte can happen depends on the frequency of vomiting Risk factors present on the patients for gastric malignancy - possible H. pylori infection - chronic gastritis (90% H. pylori) - tobacco smoking – inhibit prostaglandin secretion Atrophic Gastritis • Most common precancerous lesion • Chronic H. pylori infection- the most common cause • Other causes: o Pernicious anemia o Bile reflux • Serum Markers o Increased gastrin – response to dec in parietal cell, thus dec in HCl § Acidic environment – strongest factor of gastrin stimulation o Iron deficiency anemia –decrease iron absorption, decrease vit B12 absorption (ileum), deficiency of intrinsic factor § Vit B12 necessary for RBC synthesis o Hypo/achlorhydria OLGA staging system - determine the risk severity of gastritis - the higher the score, the greatest the risk factor Presence of goblet cells confirms the presence of metaplasia. H. Pylori ~ most common cause in gastric lymphoma (nonsurgical) - important to know the environment the mucosal lining to prevent progression. • Dysplasia o Mild § Endoscopic surveillance § H. pylori eradication o Severe § Widespread/multifocal § Resection (endomucosal) § Localized - EMR EGD • • Gastric ulcer o Antrum to pylorus o Partial gut obstruction Duodenum o D1, D2: normal TYPE 2,3 – hypersecreters Pathological diagnosis: Adenocarcinoma • Poorly differentiated with signet-ring features (aggressive) • Mucin secreting tumor Determines aggressiveness, Depth of involvement, Mucin secreting- is bad news even in colon Microscopic Descriptions • Gastric submucosa has been replaced by small dyscohesive clusters of irregular glandular structures with Mucinous cells where some appear signet ring. There was a mixed inflammatory cell infiltrates. HISTOLOGY TYPES • Lauren Classification: Separates gastric cancers into: o Intestinal type (53%) o Diffuse type (33%) o Unclassified (14%) Intestinal Type Diffuse Type • • • • • • • • • Arises from older population with an increased incidence in men. Associated with H. pylori infection, chronic atrophic gastritis and intestinal metaplasia Constitutes 60% of gastric Ca and frequently occur in the antrum as exophytic bulky lesions Have the tendency to spread hematogenously Often occurs in younger patients with equal distribution among men and women Tends to spread by direct tumor extension, resulting to peritoneal metastasis Believed to derive de novo from peripheral stem cells of gastric gland Grossly appears rigid, thickened, leather bottle appearance of the gastric wall Most aggressive, can involve the whole layers of stomach Stage the patient by using CT scan. Endoscopic ultrasound - Accurate for local staging gastric adenocarcinoma - Ideally, must be performed prior to treatment - Determine the depth of invasion of the carcinoma - Can further categorize the resectability of the patient - Can stage the patient better than CT scan CT scan – to see the involvement of other organs MRI – best assess soft tissue tumors Criteria of Unresectability for Cure: • Locoregionally Advanced ~ sometimes cannot be resected o Infiltration of the root of the mesentery o Lymph Node highly suspicious on imaging o Invasion/encasement of major vascular structures excluding splenic vessels • Distant Metastasis/Peritoneal seeding Metastatic Adenocarcinoma ~ adjunct • HER 2Neu o Principle in breast and gastric CA is the same o If (+), very aggressive o Immunohistochemistry § 0-1: negative § 2: equivocal § 3 or more: positive ~ targeted therapy o If equivocal, do FISH (Fluorescence In Situ Hybridization) § Trastuzumab • PDL-1 (programmed cell death-1) Protein when overly expressed, immune system is immunocompromised § Pembrolizumab (monoclonal antibody) GOLD STANDARD – SURGERY (Radical subtotal gastrectomy) RESECTION R classification (residual tumor) - R0: tumor resected macroscopically and microscopically completely. - R1: tumor resected completely macroscopically but incomplete microscopically - R2: resection incomplete macroscopically D1 – less aggressive, less resection, less morbidity, faster surgery D2 – more adequate resection; more morbidity; involves splenectomy D3 – more aggressive – paraaortic At least 15 lymph nodes to dissect as representative in D1 or D2. <15, if (-) it doesn’t mean it is really negative because it didn’t meet the required LN or it didn’t get the representative number. Correct staging is very important, because postoperative surgery will depend on pathological staging. D1 vs D2 dissection • Randomized trials and meta-analysis in both Asian and Western populations • MRC trial • Dutch trial o Failed to demonstrate survival benefit of D2 over D1 in dissection o *Uptodate D1 Radical Substotal Gastrectomy All nine LN harvested are negative for metastasis STAGE 1B, Nx, M0 initially TREATMENT: • Inadequate lymphadectomy, node positive or incomplete resected disease o ChemoRT + Chemotherapy § 28 day cycle of FOLFOX § Continuous infusion of FU during the entire course of RT § * CALGB trial (UpToDate) • Follow-up o History and PE § Every 3-6 month for 1-3 years § Every 6 months for 3-5 years, then annually o CBC o Tumor Markers (CEA, CA19-9) o Imaging and Endoscopy (Current surgical therapy) CA19-9 (not specific) 5FU – increases sensitivity of cancers cells to RT. Tumor markers – depends on the basis on your history and PE; a (-) TM doesn’t rule out malignancy. The prognostic factors depend on the node involvement, histologic make-up of the tumor, and risk factors of the px. Incorrect assessment leads to incorrect surgical procedures.
