The Scourge of Stomach Cancer
Stomach cancer is a major clinical burden. Globally it is the 4th most common cancer, and 2nd most common cause of cancer death. In both Malaysia and Singapore, it ranks among the top 10 cancers. In Malaysia, the 2003 Cancer Registry Data showed that stomach cancer is the 7th most frequent cancer among males, and 9th most frequent cancer among females. In Singapore, it is the 4th most common cancer in males and ranks 6th in females. In both Malaysia and Singapore, among the different ethnic groups, the Chinese, especially males, have the highest risk for stomach cancer. The risk for stomach cancer also increases with age, especially after age 40 – 50 years.
Stomach cancer may be totally without any symptoms at the early stage. It could also manifest as mild upper abdominal discomfort. When more worrisome symptoms such as severe pain, weight loss and difficulty in swallowing occur, it is usually at an advanced stage and curative treatment would no longer be possible. Unfortunately, most patients consult a doctor only at such a late stage, and this has resulted in very poor overall
survival for patients with stomach cancer even with treatment. The 5-year survival rate was estimated to be 27% in Western Europe. In Japan, the estimated survival rate was better at 52%, due to frequent earlier diagnosis from a national program of stomach cancer screening. Hence it is important that when an individual has persistent upper abdominal discomfort, a doctor should be consulted so that a proper medical evaluation can be performed. This is especially crucial when certain risk factors are present, such as a positive family history of stomach cancer and an older age.
Traditional Curative Treatment
The most sensitive and accurate method of diagnosing stomach cancer is to perform endoscopy. This involves inserting a small calibre fibreoptic tube with a video camera at its tip into the stomach cavity. The endoscopist can examine the entire stomach wall visually and take tissue samples of suspicious areas for histological confirmation. Once the diagnosis is confirmed, the stage of the cancer is assessed using further tests such as computer tomography to determine whether curative treatment is possible. Traditionally whether the stomach cancer is at a very early stage, being limited to the most superficial layer of the stomach wall or when it is at a more advanced stage, with invasion through the entire stomach wall, the procedure of choice for curative treatment is surgery. Depending on the location of the cancer, either the entire stomach or half of the stomach will be cut away (gastrectomy). The main drawback with gastrectomy is that there is loss of the normal stomach function. There is also a period of convalescence as the patients recovers. Food intake would have to be reintroduced gradually since the integrity of the digestive tract has been interrupted and one needs to wait for the surgical wounds to heal.
Curative Endoscopic Therapy
 Based on scientific data, it is now quite clear that when stomach cancer is localised and restricted to the topmost superficial layer of the stomach wall (this layer is termed mucosa), regardless of the lateral extent of the cancer, the risk of microscopic spread to more distant locations is nil to minimal. This makes the process of performing the traditional treatment of either partial or total gastrectomy excessively invasive. In recent years, whenever the expertise is available, more and more doctors are adopting the technique of endoscopic submucosal dissection (ESD) to treat such cases of early stomach cancer. In this technique, the patient with the early cancer undergoes endoscopy, as described earlier. There are no external surgical incisions. The area of the stomach wall with the early cancer is identified visually (Figure 1).
Dye is sprayed around it to show up the margins better. Using an endoscopic knife, the lateral borders of the cancer is clearly marked out first, in order to ensure the entire cancer is cut out in one piece later. The superficial layer containing the cancer is then separated from the deeper muscular wall by the injection of a solution. Thereafter with the use of various endoscopic knives, this superficial layer with the cancer is cut away in one piece (Figure 2), leaving behind an ulcer base (Figure 3). Simplistically, it is similar to peeling away the skin of a fruit. This procedure does not cause any break in the normal stomach wall, and therefore it fully preserves stomach function. It will also lead to faster recovery since there are no surgical wounds. More importantly, research has shown that the long term success rate with this novel treatment is similar to open surgery.
 
As with all procedures and surgery, ESD is not without its risks. The main risk is perforation, which is about 4 per cent. But in over 95 per cent of the instances, the perforation can be treated endoscopically by endoscopic clipping, with no need for surgery. In addition, in about 3 per cent of the cases, there may be delayed bleeding, which is also easily treated by endoscopy.
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