Gastric cancer has an appalling prognosis despite treatment, and earlier diagnosis has been advocated in an attempt to improve this. Unfortunately, earlier diagnosis does not necessarily mean longer survival. The patient is merely operated on at an earlier date and, although the survival may appear longer, death will still occur at the same time from the point of genesis of the cancer (called lead time bias). With length time bias a greater number of slowly growing turnours are detected when screening asymptomatic individuals. In Japan, mass screening with mobile X-ray units has increased the proportion of early gastric cancers diagnosed. Early gastric cancer is defined as a carcinoma that is confined to the mucosa or submucosa. It is associated with 5-year survival rates of approximately 90%. In a large series of patients with gastric cancer from the UK, only 0.7% were identified as having early gastric cancer and therefore screening would not be warranted.
An effective screening procedure should:
• Be cheap
• Be acceptable to all social groups so that they attend for examination
• Have a good discriminatory index from benign lesions
• Result in an improvement in prognosis
Unless all these criteria are fulfilled, screening is unwarranted except possibly in individuals with an increased risk for the disease. Nevertheless, even in this high-risk group, screening asymptomatic subjects is not justified as the overall benefit is minimal.
An alternative approach to screening asymptomatic patients is to investigate symptomatic patients as quickly as possible. At the present time the mean interval between the onset of symptoms and attendance at hospital is approximately 6-9 months. However, dyspepsia is very common in the general population without any gastric lesions and it would obviously be impractical for every dyspeptic member of the general population to consult a physician. Even if they did, most primary physicians would think it unjustified to arrange a complicated series of investigations on the first visit. Thus, the detection of early gastric cancer in symptomatic patients is not a feasible proposition at present.
Most gastric cancers occur in the antrum and are almost invariably adenocarcinomas. The common type is ‘intestinal’ and the turnours are polypoid or ulcerating lesions with heaped-up, rolled edges. Intestinal metaplasia is often seen in the surrounding mucosa, along with H. pylori. The diffuse type is composed of scattered or small clusters of cells, often with extensive submucosal spread which may result in the picture of ‘linitis plastica’, where the stomach appears rigid on X-ray.
The commonest symptom is epigastric pain, which is indistinguishable from the pain of peptic ulcer disease, both being relieved by food and antacids. The pain can vary in intensity, but may be constant and severe. Mostpatients with carcinoma of the stomach have advanced disease at the time of presentation, and also have nausea, anorexia and weight loss. Vomiting is frequent and can be severe if the turnour is near the pylorus. Dysphagia can occur with turnours involving the fundus. Gross haematemesis is unusual, but anaemia from occult blood loss is frequent.
Patients can present with metastases causing abdominal swelling due to ascites or jaundice due to liver involvement. Metastases also occur in bone, brain and lung, producing appropriate symptoms.
Nearly 50% of patients have a palpable epigastric mass with abdominal tenderness. Often weight loss is the only feature. A palpable lymph node is sometimes found in the supraclavicular fossa (Virchow’s node) and signs of metastases are present in up to one-third of patients. Carcinoma of the stomach is the cancer most frequently associated with dermatomyositis and acanthosis nigricans.
ROUTINE FULL BLOOD COUNT AND LIVER BIOCHEMISTRY.
This is necessary to look for anaemia and possible liver metastases.
BARIUM MEAL. A good quality, double-contrast barium meal has a diagnostic accuracy of up to 90%. The carcinoma is usually seen as a filling defect or an irregular ulcer with rolled edges. With the infiltrating type, the Xray may show a rigid stomach.
GASTROSCOPY . Gastroscopy is usually performed as the primary procedure and has the advantage that biopsies can be performed for histological assessment and to exclude lymphoma. Positive biopsies can be obtained in almost all cases of obvious carcinoma, but a negative biopsy does not necessarily rule out the diagnosis. For this reason, eight to ten biopsies should be taken from around the ulcer margin and its base. Superficial brushings for cytology will further improve the diagnostic rate.
CT, MRI AND ULTRASOUND. These are used to stage for operability, but have been disappointing in detecting nodular and peritoneal metastases. Endoscopic ultrais sound is now being used to stage the depth of the primary invasion.
The 5-year survival rate of patients operated on for early gastic cancer (EGC) in Japan is 90%, but outside Japan EDC is rare. Surgery remains the best form of treatment if the patient is operable. Better preoperative staging hasreduced the numbers undergoing operation and has improved the 5-year survival rates to around 30%. In curative operations, 5-year survival rates are as high as 50%.Despite these improved figures, the overall survival rate for a patient with gastric carcinoma has not dramaticed, cally advanced with a 10% 5-year survival. Treatment with chemotherapy has made little impact and is currently not justifiable apart from in clinical trials. Survival may be prolonged by a few months but the toxicity of the drugs limits their use. Cimetidine has been used with some success in trials. Palliative care with relief of pain and counselling is essential
Lymphome of the stomach can account for 10% of all gastic malignancies in the developed world. It is a nonlymphoma Hodgkins lymphome of the B cell type arising from mucosal-associaated lymphoid tissue. H. pylori is thought to play an aetiological role. Clinical presentation is the same as gastic carcinoma. Treatment is surgical with postoperative radiotherapy and chemotherapy. Eradication of H. pylori is strongly recommended. Prognosisis good with a 75 % 5 year survival depending on the type of lymphoma.