Stomach Cancer

Stomach (gastric) cancer arises in the stomach but can spread to the esophagus as well as to the lungs, lymph nodes and liver. There are two main classes: gastric cardia cancer (at the region where the stomach meets the esophagus) and non-cardia gastric cancer (cancer elsewhere in the stomach). There are about one million new cases every year. It is the fourth most common cancer worldwide and the tenth most common adult cancer in the UK, causing over 700,000 deaths per year worldwide. Over 70% of cases are in developing countries with half the global total being in Eastern Asia.

New cases/year World 2008: 988,000; [male: 640,000, female: 348,000];

USA 2010 (est): 21,000; UK 2008: 7,610

Deaths/year World 2008: 736,000; [male: 463,000, female: 273,000];

USA 2010 (est): 10,570; UK 2008: 5,178

Risk factors Most diagnoses in those over 65 years of age. More common in men than in women. Most (65-80%) caused by Helicobacter pylori infection although cancer only arises in about 2% of infected individuals. Other contributory factors are diet (low in fruit and vegetables, high in salted or preserved foods), smoking and a family history of gastric cancer.
Symptoms Vague but may include heartburn, abdominal discomfort, bleeding and difficulty in swallowing.
Staging TNM system is used (see Tumour staging).
Classification Over 95% are adenocarcinomas of which there are two major types: intestinal (generally well differentiated) and diffuse (generally poorly differentiated). Gastrointestinal stromal tumours (GIST), lymphoma and neuroendocrine tumours arise infrequently in the stomach.
Major gene mutations Inherited mutations in E-cadherin (CDH1) or BRCA2 promote hereditary diffuse gastric cancer.Somatic mutations identified in KRAS and BRAF. Mutations in P53 or PLCE1 associated with gastric cardia cancer.
Treatment Surgery. Chemotherapy commonly ECF (epirubicin, cisplatin and 5-fluorouracil) or ECX (epirubicin, cisplatin and capecitabine). Radiotherapy not routinely used.
Side effects Nausea, hair loss, diarrhoea, mouth ulcers and general suppression of the immune system and increased infection risk.
Prognosis Over 50% cure rate for localized (early stage) disease. However, most patients (80%) present with metastases. Depending on the extent to which affect tissue can be resected, 5-year survival rates range from 10% to 50%.