Treatment & Management of Gastric Cancer
Medically reviewed by C.H. Weaver M.D. Medical Editor (08/2018)
Surgery is part of the standard treatment for the majority of patients with gastric cancer. However, since gastric cancer is not exclusively treated by surgery, it is important for patients to be treated at a medical center that can offer multi-modality treatment involving surgeons, gastroenterologists, radiation oncologists, medical oncologists and nutritionists. Multi-modality therapy may consist of chemotherapy, radiation, and precision cancer medicines.
Systemic therapy is any treatment directed at destroying cancer cells throughout the body, and may include chemotherapy or newer precision cancer medicines or immunotherapy. Treatment of patients with stage II - III or locally advanced gastric cancer often consists of systemic treatment combined with surgery or radiation and systemic treatment is routinely used in stage IV or recurrent cancer.
Surgery for Gastric Cancer
Individuals with gastric cancer are frequently treated with surgical removal of the stomach (called a gastrectomy), to remove the cancer and prevent recurrence (or return) of the cancer. Lymph nodes (parts of the body’s lymph system) around the stomach are also removed and examined to determine whether or not the cancer has spread to these areas. Depending on the stage (extent of disease) of the cancer, the majority of patients will also be treated with chemotherapy drugs and/or radiation therapy.
A complete removal of the primary cancer and the lymphatic drainage of the cancer is the primary goal of any surgical treatment for gastric cancer. Patients with gastric cancer may have a total or partial removal of the stomach. When patients undergo a partial removal of the stomach, the remaining portion of the stomach is re-attached to the upper part of the small intestine (duodenum) or to the middle part of the small intestine (jejunum) or to the esophagus. Cure rates for gastric cancer are related to the extent of cancer at the time of diagnosis.
During a total gastrectomy, the entire stomach is removed and the two remaining ends of the gastrointestinal tract are reconnected. This is the most common operation for cancer of the upper stomach. For cancers of the middle and lower stomach, an incision is made in the abdomen and the entire operation can be carried out without entering the chest. The usual operation for cancer of the upper stomach, called the cardia, is an incision that involves entering both the abdomen and the chest. An alternative approach is a single incision in the abdomen with an incision through the diaphragm (transhiatal approach). The transhiatal approach for total gastrectomy for cancer of the upper stomach is a safe alternative to the standard thoracoabdominal technique and avoids entering the chest and the associated complications.
Treatment of patients with cancer of the lower part of the stomach has frequently involved the complete removal of the stomach. An alternative operation is removal of only the part of the stomach involved with cancer with preservation of the upper stomach. This is called a subtotal gastrectomy. The less extensive operation is associated with better nutrition and quality of life than total gastrectomy.
Early cancers (Stage 0 and I) can often be removed through an endoscope passed through the esophagus. Another procedure, called laparoscopic surgery, is performed through an endoscope passed into the abdomen through a small incision. Studies conducted thus far suggest that laparoscopic surgery is safe and effective for selected patients; additional, larger studies are needed before firm conclusions can be drawn. The primary advantage of laparoscopic surgery is more rapid recovery after surgery.
Extent of Surgery
Lymphocytes and the lymph system are part of the body’s immune system that protects the body from disease and infection. The lymph system consists of small bean-shaped “lymph nodes” connected by ducts, which are extensively located throughout the gastrointestinal tract. When cancer originates in the stomach, cancer cells may spread through the lymph nodes to other parts of the body.
In some, but not all clinical studies, improved survival is associated with more extensive removal of the lymph nodes. This has led some surgeons to recommend removing the maximum number of lymph nodes during surgery. However, this more extensive surgery is often associated with increased complications. Thus, controversy remains regarding the appropriate extent of lymph node removal.
Adjuvant Therapy (Treatment after Surgery)
It is important to understand that some patients with gastric cancer already have small amounts of cancer that have spread beyond the stomach and cannot be detected with any of the currently available tests. Undetectable areas of cancer are referred to as micrometastases.
It is the presence of micrometastases that causes cancer recurrence following treatment with surgery alone. For some patients, additional treatment aimed at these micrometastases can improve duration of survival and potential for a cure. The delivery of cancer treatment following local treatment with surgery is referred to as adjuvant therapy. Adjuvant therapy for gastric cancer typically involves chemotherapy, sometimes in combination with radiation therapy.
Neoadjuvant Therapy (Treatment before Surgery)
Some patients may receive treatment with chemotherapy (with or without radiation therapy) prior to surgery. This treatment can help to reduce the extent of cancer, making it easier to remove the cancer during surgery. Patients who receive chemotherapy prior to surgery often receive chemotherapy after surgery as well.
Adjuvant Therapy: The administration of additional treatment after surgery for the purpose of decreasing the risk of cancer recurrence is referred to as adjuvant therapy. Clinical trials have demonstrated an improvement in survival when adjuvant therapy is used to treat all stages of gastric cancer except stage IA. Clinical trials are ongoing to determine the optimal adjuvant therapy.
Radiation Therapy for Gastric Cancer
Radiation therapy may be an integral part of the treatment of gastric cancer. However, since gastric cancer is not exclusively treated with radiation therapy, it is important for patients to be treated at a medical center that can offer multi-modality treatment involving medical oncologists, radiation oncologists, surgeons, medical gastroenterologists, and nutritionists.
The objective of radiation therapy to the stomach is to kill cancer cells that could otherwise persist and cause the cancer to relapse. Radiation therapy uses high energy x-rays to kill cancer cells that remain in or near the stomach and surrounding lymph nodes. Radiation therapy is usually delivered to the stomach and surrounding lymph nodes from a machine outside the body, called a linear accelerator.
Radiation therapy alone is not usually recommended for primary treatment of gastric cancer because radiation administered in combination with chemotherapy appears superior when compared to treatment with radiation alone. Radiation therapy, however, is utilized as palliative therapy for patients who have inoperable gastric cancer or for patients who cannot undergo surgery or chemotherapy. Radiation therapy can also be utilized to treat patients who have a recurrence after surgery. However, in this situation patients typically also receive simultaneous chemotherapy and radiation therapy.
Adjuvant Therapy (Treatment after Surgery)
It is important to understand that some patients with gastric cancer already have small amounts of cancer that have spread beyond the stomach and cannot be detected with any of the currently available tests. Undetectable areas of cancer are referred to as micrometastases. It is the presence of micrometastases that causes cancer recurrence following treatment with surgery alone. For some patients, additional treatment aimed at these micrometastases can improve duration of survival and potential for a cure. The delivery of cancer treatment following local treatment with surgery is referred to as adjuvant therapy. Adjuvant therapy for gastric cancer may involve chemotherapy alone or in combination with radiation therapy.
Neoadjuvant Therapy (Treatment before Surgery)
Some patients may receive treatment with chemotherapy or chemotherapy plus radiation therapy prior to surgery. This treatment can help to reduce the extent of cancer, making it easier to remove the cancer during surgery.
Metastatic or Recurrent Cancer
The role of radiation therapy is limited in patients with unresectable or stage IV metastatic cancer. The primary treatment remains combination chemotherapy. Radiation therapy alone, however, can be used to decrease the symptoms from gastric cancer in patients with more advanced disease who are medically unable to receive surgery or chemotherapy or for patients who have a recurrence after surgery. However, patients with recurrent cancer usually receive combination chemotherapy.
Delivery of Radiation Therapy for Gastric Cancer
Modern radiation therapy for gastric cancer is delivered via machines called linear accelerators that produce high energy external radiation beams that penetrate the tissues and deliver the radiation dose deep into the areas where the cancer resides. These modern machines and other state-of-the-art techniques have enabled radiation oncologists to significantly reduce side effects, while improving the ability to deliver a curative radiation dose to cancer-containing areas and minimizing the radiation dose to normal tissue. For example, with modern radiation therapy, skin burns almost never occur, unless the skin is being deliberately targeted or because of unusual patient anatomy.
After an initial consultation with a radiation oncologist, the next session is usually a planning session, which is called a simulation. The simulation session is used to determine radiation treatment fields and most of the treatment planning. Of all the visits to the radiation oncology facility, the simulation session may actually take the most time. During simulation, detailed pictures are taken of the cancer and the areas surrounding the cancer, often using computed tomography (CT) scans. Temporary marks may be made on the patient’s skin with magic markers. Body molds or other devices may be constructed to help the patient stay in one position. The radiation oncologist is aided by one or more radiation technologists and often a dosimetrist, who performs calculations necessary in the treatment planning. The simulation may last anywhere from fifteen minutes to an hour or more, depending on the complexity of what is being planned.
Once the aspects of the treatment fields are satisfactorily set, the patient may be given multiple “tattoos” which mark the treatment fields and replace the marks previously made with magic markers. These tattoos are not elaborate and consist of no more than pinpricks followed by ink, appearing like a small freckle. Tattoos enable the radiation technologists to set up the treatment fields each day with precision, while allowing the patient to wash and bathe without worrying about obscuring the treatment fields. Radiation treatment is usually given in another room separate from the simulation room. The treatment plans and treatment fields resulting from the simulation session are transferred over to the treatment room, which contains a linear accelerator focused on a patient table. The treatment plan is verified and treatment started only after the radiation oncologist and technologists have rechecked the treatment field and calculations, and are thoroughly satisfied with the “setup”.
Side Effects of Radiation Therapy
The majority of patients are able to complete radiation therapy without significant difficulty. Side effects and potential complications of radiation therapy are limited to the areas that are receiving treatment with radiation. The chance of a patient experiencing side effects, however, is highly variable. A dose that causes some discomfort in one patient may cause no side effects in other patients. If side effects occur, the patient should inform the technologists and radiation oncologist because treatment is almost always available and effective.
Radiation therapy to the abdominal/pelvic area may cause diarrhea, abdominal cramping or increased frequency of bowel movements or urination. These symptoms are usually temporary and resolve once the radiation is complete. Occasionally, abdominal cramping may be accompanied by nausea.
Blood counts can be affected by radiation therapy. In particular, the white blood cell and platelet counts may be decreased. This is dependent on how much bone marrow is in the treatment field and whether the patient has previously received or is receiving chemotherapy. These changes in cell counts are usually insignificant and resolve once the radiation is completed. However, many radiation therapy institutions make it a policy to check the blood counts at least once during the radiation treatments. It is not unusual for some patients to note changes in sleep or rest patterns during the time they are receiving radiation therapy and some patients will describe a sense of tiredness and fatigue.
Late complications following radiation treatment of gastric cancer are infrequent. Potential complications do include bowel obstruction, ulcers or second cancers caused by the radiation. The probabilities of these late complications are also affected by previous extensive abdominal or pelvic surgery, radiation therapy and/or concurrent chemotherapy.
Huscher CG, Mingoli A, Sgarzini G et al. Laparoscopic versus open subtotal gastrectomy for distal gastric cancer: five-year results of a randomized prospective trial. Annals of Surgery. 2005;241:232-7.