• On the lesser curvature, left gastric artery the coeliac axis, forms an anastomotic arcade with the right gastric artery, which arises from the common hepatic artery.• Branches of the left gastric artery pass up towards the cardia.• Gastroduodenal artery, which is also a branch of the hepatic artery, passes behind the first part of the duodenum → bleeding duodenal ulcer.
• Gastroduodenal artery then divided to give superior pancreaticoduodenal artery and right gastroepiploic artery.• Right gastroepiploic artery runs along the greater curvature of the stomach, eventually forming an anastomosis with left gastroepiploic artery, a branch of the splenic artery.• Fundus of the stomach is supplied by the vasa brevia (or short gastric arteries), which arise near the termination of the splenic artery.
Venous drainage• Equal to arterial supply• Those along the lesser curve ending in the portal vein and those on the greater curve joining via the splenic vein.• Coronary vein - runs up the lesser curve towards the oesophagus and then passes left to right to join the portal vein → markedly dilated in portal hypertension.
• Antrum → right gastric lymph node superiorly and the right gastroepiploic and subpyloric lymph nodes inferiorly.• Pylorus → right gastric suprapyloric nodes superiorly and the subpyloric lymph nodes situated around the gastroduodenal artery inferiorly.• Efferent lymphatics from the suprapyloric lymph nodes converge on the para-aortic nodes around the coeliac axis
• Efferent lymphatics from the subpyloric lymph nodes pass up to the main superior mesenteric lymph nodes situated around the origin of the superior mesenteric artery.• Lymphatic vessels related to the cardiac orifice of the stomach communicate freely with those of the oesophagus
Nerves• Intrinsic nerves – 2 plexus – Myenteric plexus of Auerbach – Submucosal plexus of Meissner• Extrinsic nerves, derived from vagus nerve.• Vagal plexus around the oesophagus condenses into bundles that pass through the oesophageal hiatus.• Sympathetic supply mainly from coeliac ganglia.
The anatomy of the anterior and posterior vagus nerves in relation to the stomach.
Risk Factor & Etiology of GIST Ahmad Abid Abas  Reference : American Cancer Society (GIST)
Etiology• Unknown etiology. No known lifestyle related or environmental causes.• ‘Genes and protein changes theory in GIST cells ’• Understanding this information will help to diagnose and treat this cancer.
Etiology• Genes = DNA• Oncogenes – Certain genes that help cells grow and divide.• Tumour suppressor genes – Genes that helps slow down cell division or cause cells to die at right time.
Etiology• In GIST, there is a change in oncogene called c-kit.(Receptor tyrosine kinase mutations)• It directs cell to make a protein called KIT.• Normally c-kit gene is inactive.Active during there is a need for Interstitial Cells of Cajal*. *(as pacemaker,controlling motility)• In GIST, c-kit is always mutated and active.• 85% of GIST have mutation in c-kit.
Etiology• About 15% GIST patient have mutation in another protein receptor called, PDGFR. (Platelet-Derived Growth Factor)• The gene changes is now understood by researchers but it’s still not clear what might cause this changes.
CLINICAL PICTURE OF GIST By: AHMAD DANIAL BIN AHMAD FUAD , 5
In adult GISTs• Stomach-60%• Small intestine-30%• Duodenum-5%• Colorectum-<5%• Esophagus and appendix-<1% GISTs are frequently diagnosed incidentally during endoscopic or surgical procedure. They are either asymptomatic or associated with non specific symptoms
SymptomsMost common symptoms are:• Vague, non specific abdominal pain or discomfort.• Early satiety or a sensation of abdominal fullness.GISTs may also produce symptoms secondary to obstruction or hemorrhage.Symptoms of haemorrhage• malaise, fatigue, or exertional dyspnea.Symptoms of obstruction can be site-specific• (eg, dysphagia with an esophageal GIST,
Signs• Abdominal mass• Vital sign abnormality, shock d.t GI blood loss• Distended tender abdomen d.t bowel obstruction• Jaundice if obs. involving ampulla• Sign of peritonitis if perforation has occurred
LAB TEST No xpecific test,the following tests are generally ordered in the workup of the patient who presents with nonspecific abdominal symptomatology;• Complete blood cell count• Coagulation profile• Serum chemistry studies• BUN and creatinine• Liver function tests and amylase and lipase values• Type and screen, type and crossmatch• Serum albumin
IMAGING : BARIUM STUDY• can usually detect GISTs that have grown to a size sufficient to produce symptoms.• a filling defect that is sharply demarcated and is elevated compared with the surrounding mucosa,• the contour of the overlying mucosa is smooth unless ulceration has developed because of growth of the underlying tumor
IMAGING : CT• It provides comprehensive information regarding the size and location of the tumor and its relationship to adjacent structures.• CT scanning can also be used to detect the presence of multiple tumors and can provide evidence of metastatic spread.
IMAGING ; MRI• MRI has not been studied as intensively as CT scanning in the application of diagnosing GISTs.• It appears to be just as sensitive as CT scanning
IMAGING ; PET• has recently been touted as an excellent study for detecting metastatic disease. It has also been used to monitor responses to adjuvant therapies such as imatinib mesylate.
ENDOSCOPY• Endoscopic features of GISTs include the suggestion of a smooth submucosal mass displacing the overlying mucosa.• Some may be associated with ulceration or bleeding of the overlying mucosa from pressure necrosis.
ENDOSCOPIC ULTRASOUND• The typical endoscopic ultrasonographic appearance of a GIST is a hypoechoic mass situated in the layer corresponding to the muscularis propria.• Fine-needle aspiration biopsy specimens also may be obtained via the endoscope under sonographic guidance.
Surgical treatment• Surgery is the mainstay of therapy for nonmetastatic GISTs• Routine lymphadenectomy is not indicated, as lymph node involvement is very rare.• The decision of appropriate laparoscopic surgery is affected by tumor size, location, and growth pattern
• After surgery, patients who may have a high risk of recurrence often receive imatinib for at least three years.• This is a type of treatment called adjuvant therapy
Indications for surgery• For small gastric tumors, wedge resection is adequate, if technically possible.• Larger tumors necessitate subtotal or total gastrectomy.• Also consider resection in patients with recurrent disease, manifested as a solitary lesion in the liver or peritoneal cavity.• in cases of disseminated disease, consider palliative
• For locally invasive tumors, en bloc resection of adjacent involved organs, such as colon, spleen, or liver.• The goal is complete resection of the mass without disruption of pseudocapsule• Segmental resection with negative microscopic margins is the preferred intervention
Targeted Therapy• Targeted therapy is a treatment that targets the tumor’s specific genes, proteins, or the tissue environment that contributes to the tumor’s growth and survival.• Evidence of benefit in1. Treatment of advanced GIST2. As adjuvant to 1ry tumour resection
• Tyrosinekinase inhibitor imatinib (Glivec/Gleevec) ,a drug initially marketed for CML was found to be useful in treating GISTs• It is usually given alone or in combination with surgery (either before or after surgery) and is given for a long time.• For patients with GIST that has spread to other parts of the body, imatinib is taken for the rest of the patient’s life to help control the tumor.
Imatinib Mesylate: Mechanism of Action•Imatinib mesylate occupiesthe ATP binding pocket of thec KIT kinase domain c KIT•This prevents substratephosphorylation andsignaling P Imatinib ATP•A lack of signaling inhibits mesylateproliferation and survival P P P SIGNALINGSavage and Antman. N Engl J Med. 2002;346:683.
• The usual dose of imatinib is 400 milligrams (mg) daily.• The most common side effects of imatinib are fluid accumulation, rash, nausea, and minor muscle aches.• Serious but relatively rare side effects include bleeding and inflammation of the liver.
• Patients who develop resistance to imatinib may respond to the multiple tyrosine kinase inhibitor sunitinib (marketed as Sutent)• Itis a tyrosine kinase inhibitor called an anti- angiogenic that is focused on stopping angiogenesis• Because a tumor needs the nutrients delivered by blood vessels to grow and spread, the goal of anti-angiogenesis therapies is to “starve” the tumor.
Radiation therapy• Radiation therapy is not often used for GIST, as it is unclear whether it helps to shrink the tumor.• However, it may be used as a palliative treatment to relieve pain or stop bleeding.• Side effects from radiation therapy include tiredness, mild skin reactions, upset stomach, and loose bowel movements.