What are the treatments for gastric cancer

Currently, all curative treatments for gastric cancer involve surgery (surgical resection of all of the cancer). The smallest amount of surgery that is possible while still taking out all of the cancer is what is normally performed. Generally, tumors which are localized to the part of the stomach closest to the esophagus (proximal stomach) are treated with a gastrectomy (removal of the entire stomach). A partial gastrectomy is the removal of only a portion of the stomach, in contrast to a total gastrectomy, which is done when the tumor is larger. Partial gastrectomies may be appropriate for those tumors located further from the esophagus, in the distal portion of the stomach. For partial gastrectomy, the surgical margin around the gastric cancer needs to be 5 cm, i.e., there needs to be 5 cm of normal stomach tissue around the tumor in the portion of the stomach removed. Diffuse disease involving the stomach is also an indication for a total gastrectomy. Also, the surgeon performs a complete dissection of the lymph nodes, removing as many as possible. How extensive of a lymph node dissection to perform is controversial, with contradictory data from the United States compared with Japan. However, it is import that an experienced surgeon perform the dissection as it is a difficult surgery. Obviously, when the stomach or a portion of the stomach is removed, the two ends must be rejoined. This is done by various procedures, all attempting to eliminate as many of the side effects of the surgery as possible, such as inability to eat larger meals and the so-called "dumping syndrome". Dumping syndrome results from the stomach being removed and the result of the small intestine filling too rapidly with undigested food. Symptoms include nausea, vomiting, bloating, diarrhea, and even shortness of breath. These symptoms can usually be managed with dietary modifications.

Although surgery is always required for curative treatment, it is often not enough to achieve cure in many cases. The majority of cases of early gastric cancer are cured by surgery alone. However, in most patients with more advanced cases of gastric cancer, such as those with positive lymph nodes or tumors which have invaded the deep layers of the stomach or beyond, the cancer will come back if only surgery is done. Up to two-thirds of these patients recur, with cancer coming back in their lymph nodes or other organs. To combat this, radiation therapy and chemotherapy are recommended in many patients. It is felt that any patient with stage IB or higher gastric cancer (involvement of deeper portions of the stomach wall or any lymph nodes involved with cancer) will benefit from additional therapy with concurrent radiation and chemotherapy.

Radiation therapy makes the use of high energy x-rays to kill cancer cells. It does this by damaging the DNA in tumor cells. Normal cells in our body can repair radiation damage much quicker than tumor cells, so while tumor cells are killed by radiation, many normal cells are not. This is the basis for the use of radiation therapy in cancer treatment. Radiation is delivered using large machines that produce the high energy x-rays. After radiation oncologists set up the radiation fields ("radiation fields" are the areas of the body that will be treated by radiation), treatment is begun. Radiation is given 5 days a week for approximately 5 weeks at a radiation treatment center. The treatment takes just a few minutes each day and is completely painless. The typical radiation field used in the treatment of gastric cancer includes portions of the upper abdomen. In other words, it is designed to kill tumor cells in the area that the surgery was performed. Typical side effects include nausea and vomiting (though this should be less of a problems since the stomach has already been removed) and diarrhea.

Chemotherapy is defined as drugs that are used to kill tumor cells. The large advantage in using chemotherapy is that, since it is a medicine, is travels through the entire body. Hence, if some tumor cells have spread outside of what surgery or radiation can treat, they can potentially be killed by chemotherapy. Similar to radiation, some normal cells are damaged during treatment, resulting in side effects. The standard chemotherapy used in the treatment of gastric cancer is called 5-FU, coupled with another drug called leucovorin. This type of chemotherapy is delivered through the vein. Side effects from 5-FU and leucovorin include nausea, diarrhea, skin changes, and sores of the mouth. Although other chemotherapy drugs (cisplatin, oxaloplatin, epirubicin) are being investigated for the treatment of gastric cancer, 5-FU plus leucovorin remains the standard. Sometimes chemotherapy and radiation are used prior to surgery, but a large trial has demonstrated that surgery follow by radiation with chemotherapy appears to be the best current treatment. The value of radiation and chemotherapy was demonstrated in a large study just reported in 2001 by MacDonald et al. These authors reported a much better outcome in patients with Stage IB or greater gastric cancer who were treated with radiation and chemotherapy after potentially curable surgery. This study has established the “standard of care” in the United States, and is detailed as follows:

• Surgery- to remove all of the cancer, as well as removal of the lymph nodes in the area of the stomach

• Radiation- to the area of the upper abdomen, 5 days per week for 5 weeks;usually starts 4-6 weeks after surgery, to allow for recovery from surgery, but may be delayed by a few weeks if chemotherapy is started first, prior to combining the two treatments.

• Chemotherapy- using 5-FU and leucovorin combination therapy, given during the radiation and also after the radiation is completed; can sometimes be started for a few weeks prior to the start of radiation therapy, to allow for local healing if needed

There has also been a study which has demonstrated the benefit of postoperative chemotherapy alone in people who may not tolerate radiation with chemotherapy. The type of chemotherapy advised in this setting is epirubicin, cisplatin and 5-fluorouracil (ECF).