Gastric carcinoma

Gastric cancer is exceptional, in that its incidence has been declining for the past 20 years whilst other gastrointestinal tumours have increased in frequency. Despite this, it remains a common cause of death in the Western world and is extremely common in China, Japan and parts of South America. Variations in populations are believed to be due to local environmental, mainly dietary, factors. Gastric cancer is more common in men and the incidence rises sharply after 50 years of age. Ninety-seven per cent of gastric cancers are adenocarcinomas; the remaining 3% are lymphomas, carcinoid tumours or sarcomas (Clark et al. 2000).

Helicobacter pylori, which is known to predispose to peptic ulcer disease, has also been linked to gastric carcinoma. HP infection may be responsible for 6070% of cases and acquisition of infection at an early age may be important. Although the majority of HP-infected individuals have normal or increased acid secretion, a few become hypo- or achlorhydric and these people are thought to be at greatest risk (www.helico.com accessed 8 May 2004).

Recognised dietary factors associated with gastric carcinoma include foods that are rich in salted, smoked or pickled foods (such as vegetables, fish and meat) and the consumption of nitrites and nitrates are also associated with cancer risk. Carcinogenic N-nitroso-compounds are formed from nitrates by the action of nitrite-reducing bacteria which colonise the achlorhydric stomach. A diet which is lacking in fresh fruit and vegetables as well as vitamins A and C may also be a contributing factor. Other recognised risk factors include smoking and heavy alcohol intake.

The clinical signs and symptoms of gastric cancer include epigastric discomfort, vomiting and presence of faecal occult blood. Depending on the location of the lesion, patients can present with a variety of symptoms including:

• unexplained weight loss

• early satiety or anorexia

• abdominal mass

• gastric outlet obstruction

• vomiting and nausea

• enlarged lymph nodes

Examination may reveal no abnormalities, but signs of weight loss, anaemia or a palpable epigastric mass are not infrequent. Jaundice or ascites may signify metastatic spread. Occasionally tumour spread occurs to the supraclavicular lymph nodes, umbilicus or ovaries. Metastases occur most commonly in the liver, lungs, peritoneum, bone and marrow.

Most adenocarcinomas arise from mucus-secreting cells in the base of the gastric crypts. Most develop on a background of chronic atrophic gastritis with intestinal metaplasia and dysplasia.

Approximately half of all gastric cancers occur in the antral region of the stomach and 20-30% are situated in the gastric body, often on the greater curve (Clark et al. 2000). About 20% occur in the cardia and this type of tumour is becoming more common.

Early gastric cancer is defined as cancer confined to the mucosa or submucosa, regardless of lymph node involvement. It is often recognised in Japan, where widespread use of endoscopic screening is practised. Most patients in the Western world present with advanced gastric cancer.

Diagnosis and staging of gastric cancer

Gastric cancer may be diagnosed by upper gastrointestinal endoscopy, CT (computerised tomography) scan, plain stomach or chest X-ray films and double-contrast upper gastrointestinal series. Upper gastrointestinal endoscopy is the investigation of choice and should be performed promptly in any patient with 'alarm symptoms' such as unexplained weight loss, rectal bleeding and a family history of gastric carcinoma. Once the diagnosis is made, further imaging is necessary for accurate staging and assessment of the tumour for resectability. Endoscopic ultrasound will demonstrate whether the lesion has penetrated the submucosa or not and will also allow for visualisation of infiltrated lymph nodes. CT scans may not demonstrate small involved lymph nodes, but will show evidence of intra-abdominal spread or liver metastases. Even with these techniques, laparoscopy may be required to determine whether the tumour is resectable.

Treatment of gastric cancer

Surgery is the treatment of choice for curable lesions. Unfortunately many gastric cancers present at an advanced stage; patients may have an enlarged liver and associated jaundice - due to blood-borne metastases. Treatment for advanced cancer is largely palliative. It involves surgical resection of the tumour to relieve obstruction or dysphagia, or to control chronic bleeding. Following surgery, combination chemotherapy may be used alone or in conjunction with localised radiotherapy. Complications of gastric cancer, such as perforation and obstruction, should be managed as and when they occur.

Carcinomas at the cardia of the stomach may require endoscopic dilation, laser therapy or insertion of expandable metallic stents to allow adequate swallowing.

There are many nursing responsibilities in the care of the patient with a terminal illness including: meeting the emotional needs of the individual, providing adequate nutrition, and management of the patient's pain.

Resection offers the only hope of cure and this can be achieved in 80-90% of patients with early gastric cancer. For the majority of patients who present with locally advanced disease, tumours of the distal stomach require partial gastrectomy, while cancers of the proximal body or cardia may require oesophagogastrectomy. Extensive lymph node resection may also increase survival rates but carries greater morbidity. Even for those who cannot be cured, palliative resection may be safely performed in patients with low morbidity and may be necessary if features such as gastric outlet obstruction are present.

Prognosis

Apart from patients with early gastric cancer the prognosis remains very poor, with less than 10% surviving five years (Clark et al. 2000). Even after an apparently curative resection, five-year survival is only around 20%. Thus the best hope for improved survival lies in greater detection of tumours at an earlier stage. The low incidence of gastric carcinoma in many Western countries makes widespread endoscopic screening impractical, but urgent referral and investigation of patients with new-onset dyspepsia over the age of 45, or those with 'alarm' symptoms, is essential.

Evidence-based guidelines for the management of gastric cancer have been published by Allum et al. (2002).

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