The last article contribution by Cancer Institute Hospital of JFCR covered screening and diagnosis of stomach cancer. In this piece we will be taking a look at the process of treating stomach cancer with therapeutic endoscopy in Japan.
An endoscope is a medical instrument comprised of a tube (with a lens attached at the end) that is inserted into the patient through an existing opening (e.g. the mouth or anus). In cases of gastro-intestinal cancer, it is used to observe the esophagus, stomach, and intestines. It is also used to treat abnormalities that are found.
Today, fewer stomach cancers end up metastasizing (spread from one organ to another) via lymph nodes. This is due to the fact that, in most cases, the cancer is discovered and treated early. However, we now know of certain types of stomach cancer that have a low chance of spreading via lymph nodes. As long as lymphatic metastasis does not occur and the cancer can be completely removed with an endoscope, there is a significant chance that the patient can make a full recovery.
If the cancer develops just below the surface of the mucosa (innermost layer) of the stomach and is less than 2 cm in diameter, and if its cells are differentiated (i.e. they resemble healthy cells in the mucosa), there is very little chance of lymphatic metastasis occurring. In this case, treating stomach cancer with therapeutic endoscopy is possible. Following the removal of the cancer with endoscopy, if the doctor discovers that the cancer has invaded deeper layers or spread to blood vessels or lymph nodes, there is a greater chance of lymphatic metastasis occurring. In this case, the patient will require additional surgery.
If the cancer is less than 2 cm in diameter, but is in a location that is difficult to examine with an endoscope or is technically difficult to remove with one, the patient may require surgery instead. If the cancer is more than 2 cm in diameter, but the patient is elderly or incapable of undergoing surgery, endoscopy may be offered as a less physically demanding option. Under certain favorable conditions, undifferentiated cancer may also be treated with endoscopy as part of clinical research.
There are many ways to conduct therapeutic endoscopy, and they vary from one hospital to another. Although the procedure does not involve making incisions in the abdomen, it may result in a hole forming in the stomach due to the excess removal of tissue from the stomach wall, or bleeding from the area where the tissue was removed. In these cases, the patient may need surgery.
Therapeutic endoscopy for early stomach cancer
There are two types of therapeutic endoscopy methods used for treating early stomach cancer: endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD). In EMR, saline is injected beneath the cancer to lift it. The cancer is then lassoed with a metal wire. Finally, an electric current is sent through the wire to tighten the noose until the cancer has been removed. In ESD, a drug is injected beneath the cancer to lift it. A specialized knife is then used to dissect the areas around the cancer until it has been removed. The drug is continually injected beneath the cancer throughout the process.
Although EMR is a relatively simple procedure, there is still a 5 to 10 percent chance of recurrence due to the cancer not having been entirely removed. This can occur even in instances where the cancer is less than 2 cm in diameter. With ESD, even larger cancers more than 2 cm in diameter can be completely removed during a single procedure. Therefore, the recurrence rate after ESD is very low.
In theory, ESD allows doctors to use endoscopy to treat a wider range of cancers, including large cancers that are more than 2 cm in diameter, cancers that result in ulcers, and undifferentiated cancers. However, under current Japanese guidelines published in May 2014, such applications of ESD are only allowed as part of clinical research.
Treating for the H. pylori bacterium following early stage cancer endoscopy
The most common cause of stomach cancer is H. pylori bacteria, which infect their host before they reach the age of 5. From then on, the bacteria cause continuous stomach inflammations that have the potential to result in stomach cancer. Stomach cancer tends to occur in multiple locations, and it is not uncommon (10 to 15 percent chance) for multiple stomach cancers to occur at once in a condition known as synchronous cancer. Every year, new stomach cancers develop in 3 percent of all patients who have had stomach cancer treated with endoscopy. This condition is known as metachronous cancer. The Japan Gast Study Group (of which the Cancer Institute Hospital was a member) recently found that eradicating the H. pylori bacteria existing inside the patient following endoscopic treatment of early stomach cancer cut the occurrence rate of metachronous cancer by two thirds. The Cancer Institute Hospital actively recommends H. pylori eradication to such patients. However, while the procedure reduces the occurrence rate of metachronous cancer, it does not entirely eliminate it. Patients who have received the procedure are recommended to get an endoscopic examination once a year.
Founded in 1934 and has the longest history of any hospital in Japan specializing in cancer diagnosis and treatment.