gastriccancer
- 1. Topic: Gastric Cancer Presented by: M. Awais Mehran ahmad khan Abrar khan Sayyed M. Omar Kazim ahmad Presented to: Dr. Asghar shabir
- 2. Epidemiology • Gastric cancer was the fourth most common cancer in the world in 2004, and is expected to remain fourth in 2005. • Worldwide there are 930,000 new cases and 700,000 deaths per year. Sixty percent of new cases occur in developing countries. • There is tremendous geographic variation, with the highest death rates in Chile, the former Soviet Union, China, and Japan.
- 3. Epidemiology • In the United States gastric cancer is the 15th most common cancer, with 21,860 new cases expected this year, and 11,550 deaths. • The incidence of gastric cancer has declined significantly worldwide in the last century, with a marked decline in the US since the 1930s.
- 4. Epidemiology • In New York State there were an average of 1955 cases annually between 1998-2002, with 1070 deaths. • Male to female ratio of 2:1 in the US; 3:2 in New York. • Median age at diagnosis is 65 years (40-70). Incidence increases with age, peaking in the 7th decade.
- 5. Risk Factors • Low fat or protein consumption • Salted meat or fish • High nitrate consumption • High complex carbohydrate consumption
- 6. Risk Factors • Environment • Poor food preparation (smoked/salted) • Lack of refridgeration • Poor drinking water (well water) • Smoking
- 7. Risk Factors • Social • Low social class (except in Japan) • Medical • Prior gastric surgery • H. pylori infection • Gastric atrophy and gastritis • Adenomatous polyps • Male gender
- 8. Risk Factors • Helicobacter pylori • Presence of IgG to H. pylori in a given population correlates with local incidence and mortality from gastric cancer. • Different strains elicit different antibody responses. The cagA strain causes more mucosal inflammation and thus a higher risk of gastric cancer than cagA-negative strains.
- 9. Risk Factors • Adenomatous polyps • 10-20% risk of developing cancer, especially in lesions greater than 2 cm. • Multiple lesions increase the risk of developing cancer. • Presence of polyps increase the chance of developing cancer in the remainder of mucosa. • Endoscopic surveillance is required after removal of polyps.
- 10. Anatomy • Most of the blood supply to the stomach is from the celiac artery. • Four main arteries: • Left and right gastric along the lesser curvature • Left and right gastroepiploic along the greater curvature. • Blood supply to the proximal stomach also comes from the inferior phrenic and short gastric arteries
- 11. Anatomy • Occasionally (15-20%) an aberrant left hepatic artery arises from the left gastric – a concern if the left gastric needs to be divided. • The extensive anastomotic connections between these arteries allow, in most cases, three of the four vessels to be ligated as long as the arcades between the curvatures are not disturbed.
- 13. Anatomy • Venous drainage parallels the arterial supply • Left and right gastric veins drain into the portal vein • Right gastroepiploic drains into the SMV • Left gastroepiploic drains into the splenic vein
- 14. Anatomy • Lymphatic drainage is into four zones: • Superior gastric • Suprapyloric • Pancreaticolienal • Inferior gastric/subpyloric • All four drain into the celiac group of nodes and into the thoracic duct. • Gastric cancers drain into any of these groups regardless of location of the tumor.
- 15. Anatomy • Innervation: • Parasympathetic via the vagus. • Left anterior and right posterior. • Sympathetic via the celiac plexus.
- 16. Clinical Presentation • Symptoms are often absent in early stages, and when present are often ignored, missed, or mistaken for another disease process. • Vague discomfort and/or indigestion • Epigastric pain that is constant, non-radiating, and unrelieved by food ingestion. • Proximal tumors may present with dysphagia. • Antral tumors may present with outlet obstruction.
- 17. Clinical Presentation • Diffuse mural disease may present with early satiety due to decreased distensibility. • Up to 15% of patients develop hematemesis and 40% are anemic at presentation.
- 18. Clinical Presentation • Unfortunately most patients present in later stages of disease, with evidence of metastatic or locally advanced tumor. • Palpable abdominal mass, ovarian mass, supraclavicular or periumbilical lymph nodes. • Obstruction from tumor invasion into transverse colon. • Hepatomegaly, jaundice, ascites, and cachexia.
- 19. Diagnosis • Endoscopy is the diagnostic method of choice. • With multiple biopsies (seven or more) the diagnostic accuracy approaches 98%. • Cytologic brushings can also be obtained. • Size, morphology, and location of tumor can be documented, as well as any other mucosal abnormalities.
- 20. Endoscopy
- 21. Endoscopy
- 22. Diagnosis •Double contrast barium swallow has 90% accuracy and is cost effective. • No ability to distinguish between malignant and benign ulcers.
- 23. Diagnosis • Endoscopic Ultrasound (EUS) is a newer modality that is being used in some center to help stage the tumor. • Extent of wall invasion and lymph node involvement can be assessed. • Overall accuracy is 75%. • Poor for T2 tumors (38%) • Better for T1 (80%) and T3 (90%) • Remains operator dependent.
- 24. Preoperative Workup • Once diagnosis of gastric cancer has been made, CT scan is useful for evaluation of any distant disease. • Limited in detecting early primary and small (<5mm) metastatic tumors. • Accuracy of lymph node staging ranges from 25 to 86%. • If CT scan is negative, then laparoscopy is recommended as the next step in evaluation.
- 25. Preoperative Workup • Laparoscopy detected metastatic disease in 23 to 37% of patients deemed eligible for curative resection by CT scan. • Laparoscopy improves palliation in these patients by avoiding unnecessary laparotomy in about one fourth of patients presumed to have local disease on CT scan.
- 27. Treatment Surgical resection remains the mainstay of treatment and is the only curative option. More recently pre- and post-chemoradiation therapy has been scrutinized to see if there is any benefit to survival. The issue of extent of resection appears to have been settled. As long as adequate tumor margins are achieved, subtotal gastrectomy has the same survival as total, with decreased morbidity.
- 28. Surgical Treatment Aggressive resection of gastric cancer is justified in the absence of distant metastatic spread. The surgery is tailored mainly to the location of the tumor and known pattern of spread. R0 resection should be achieved, with a minimum of 6cm margins from gross tumor. R0 – tumor free margins R1 – microscopic disease R2 – gross tumor at margins Minimum of 15 nodes should be removed.
- 29. Surgical Treatment • Tumors in the cardia and proximal stomach account for 35-50% of gastric adenocarcinomas. For these tumors a total gastrectomy should be performed, as opposed to proximal gastric resection which is associated with higher morbidity and mortality rates. • Distal tumors may be removed by distal gastrectomy as long as adequate margins are achieved.
- 30. Surgical Treatment The extent of lymphadenectomy remains controversial. The JGCA classifies the lymph node basins into 16 basins, and are grouped according to the location of the primary tumor as either D1, D2, or D3 nodes. In general: D1 – removal of group 1 nodes along the lesser and greater curvature. D2 – D1 plus group 2 nodes along the left gastric, common hepatic, celiac, and splenic arteries. D3 – D2 plus para-aortic and distal lymph nodes
- 31. Surgical Treatment A 1993 survey by the ACS showed a 77.1% resection rate in 18,365 patients, with a postoperative mortality rate of 7.2% and 5-year survival rate of 19%. Of these only 4.7% were D2 dissections. In comparison, the Japanese routinely perform D2 dissections, with 5-year survival rates above 50%. Although earlier detection accounts for much of the survival benefit, when comparing cancers in the same stage, the Japanese continue to have improved survival.
- 32. Survival Outcomes 0 20 40 60 80 100 120 Stage I Stage II Stage III Stage IV US Japan
- 33. Surgical Treatment • Based on this and other retrospective data, four randomized studies comparing D1 to D2 dissections have been conducted. • All four trials, including two large ones from the Netherlands and Britain all show the same data; that D2 dissection significantly increases morbidity and mortality without any significant increase in survival.
- 34. Surgical Treatment • Splenectomy and pancreatectomy were found to be important risk factors for morbidity and mortality after D2 dissection. • In the DGCT trial a subgroup analysis of patients who underwent D2 without splenectomy and/or pancreatectomy had a significantly improved survival benefit. • A randomized British trial also supported these findings in stage II and III disease.
- 35. Surgical Treatment • Based on these findings, many groups are recommending “over-D1” lymphadenectomy for gastric cancers in Western society. • The large difference between the Japanese results and Western results remains largely an enigma.
- 36. Surgical Treatment • Choice of reanastamosis depends on extent of resection. • Very distal gastrectomies may be reanastamosed via a Billroth I, II, or Roux-en-Y. • Subtotal gastrectomies will require a Billroth II or Roux-en-Y. • Total gastrectomies are best served with a Roux-en-Y anastamosis.
- 37. Outcomes • What can you expect? • Patients who have undergone a potentially curative resection have an average 5-year survival of 24 to 57%. • More useful survival rates are stratified by stage of disease.
- 39. Outcomes • Recurrence rates remain high, from 40 to 80% depending on the series being quoted. • Locoregional failure rate 38 to 45%, with most recurrence in the gastric remnant at the anastamosis, gastric bed, and lymph nodes. • Surveillance is important. Patients should be followed every 4 months for the first year, then 6 months for 2 more years. Yearly endoscopy should be performed for subtotal gastrectomies.
- 40. Choice of Operation • Open gastrectomy with lymph node dissection – at least D1 – is the current operative standard. • Laparoscopic gastrectomy has been shown to be safe with similar survival for patients with distal cancer. • Learning curve needs to be overcome, which may be difficult with the decreasing number of gastric cancer cases in the U.S.
- 41. Thank you.