Radiation Therapy for Esophageal Cancer
Overview
Radiation therapy can be an integral part of the treatment of esophageal cancer. However, since esophageal cancer is not exclusively treated with radiation therapy, it is important for patients to be treated in an environment that can offer multi-modality treatment involving radiation oncologists, surgeons, gastroenterologists, medical oncologists and nutritionists.
The objective of radiation therapy to the esophagus is to kill cancer cells that could otherwise persist after therapy and cause the cancer to relapse locally. Radiation therapy uses high energy x-rays to kill cancer cells that remain in or near the esophagus and surrounding lymph nodes. Radiation therapy can be externally or internally delivered to the esophagus and surrounding lymph nodes. External beam radiation therapy (EBRT) delivers radiation from a machine outside the body, called a linear accelerator. EBRT treatments are typically delivered 5 days a week, for 2-6 weeks, depending on the overall goals of treatment and each treatment lasts between 10-15 minutes. The internal delivery of radiation therapy (brachytherapy) involves the placement of a radioactive isotope, such as iridium 192, within the esophagus.
Primary Treatment with Radiation Therapy
External beam radiation therapy alone is not usually recommended for primary treatment of esophageal cancer because radiation administered in combination with chemotherapy improves survival compared to treatment with radiation alone.
The results of radiation therapy and chemotherapy as primary treatment for esophageal cancer are presented under the treatment overviews for each stage of esophageal cancer. In general, current evidence suggests that combined chemotherapy and radiation therapy is superior to either therapy alone as primary therapy for esophageal cancer.
However, radiation therapy alone can be used to treat localized cancer in patients who cannot tolerate surgery or chemotherapy. Treatment with radiation therapy alone results in an approximate18% survival at one year, an 8% survival at two years and less than 5% survival at 5 years in patients with localized esophageal cancer (stage I-III).
Radiation therapy alone can also be used to decrease the symptoms from esophageal 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 locally recurrent cancer usually receive simultaneous chemotherapy.
Side Effects of Radiation Therapy
Radiation therapy may produce considerable short-term side effects such as mucositis (inflammation of the lining of the throat, mouth and esophagus), perforation of the esophagus with the development of fistulas (connections with other organs such as the trachea), infection, bleeding, xerostomia (dryness in the mouth) and fatigue. Changes to the esophagus and skin usually go away in 6-12 months. Some patients who respond to radiation therapy will develop strictures or narrowing of the esophagus that will require treatment in the future.
Strategies to Improve Treatment
The progress that has been made in the treatment of esophageal cancer has resulted from improved development of adjuvant treatments and doctor and patient participation in clinical studies. Future progress in the treatment of esophageal cancer will result from continued participation in appropriate studies. Currently, there are several areas of active exploration aimed at improving the treatment of esophageal cancer.
Supportive Care: Supportive care refers to treatments designed to prevent and control the side effects of cancer and its treatment. Side effects not only cause patients discomfort, but also may prevent the optimal delivery of therapy at its planned dose and schedule. In order to achieve optimal outcomes from treatment and improve quality of life, it is imperative that side effects resulting from cancer and its treatment are appropriately managed. For more information, go to Supportive Care.
New Chemoradiation Regimens: Newer chemotherapy drugs that are effective for patients with advanced esophageal cancer are being used in combination with radiation therapy. Developing single or multi-agent chemotherapy regimens in combination with radiation therapy to improve the cure rates is an area of active investigation.
Amifostine: Over the past 50 years, many drugs, called radiation protectors, have been tested in the laboratory for prevention of radiation damage to normal cells and tissues. For such drugs to work effectively they have to protect normal cells, but not cancer cells, from radiation damage. Amifostine is the only drug in this category that has been approved for use in patients receiving radiation for cancers of the head and neck. It is logical to assume that amifostine may be effective in preventing the side effects of radiation induced by treatment of esophageal cancer. Amifostine is currently being evaluated for the prevention of radiation side effects in patients with esophageal cancer.
Preoperative Radiation Therapy (Neoadjuvant Therapy): Several randomized clinical trials have directly compared the outcomes of patients receiving esophagectomy alone with the outcomes of patients receiving pre-operative radiation therapy plus esophagectomy. The results of these clinical trials indicated that pre-operative radiation therapy did not increase the number of patients able to undergo complete resection of all cancer, nor did it increase the duration of survival. However, different doses and schedules of pre-operative radiation therapy continue to be evaluated in clinical trials. In addition, some research indicates that a combination of pre-operative radiation and chemotherapy might improve survival in patients with esophageal cancer.
Brachytherapy (placement of a radioactive isotope in the esophagus): The placement of radiation directly into the esophagus increases the dose of radiation to the primary cancer, while sparing the surrounding normal structures, such as the lung, heart and spinal cord. By passing a tube through the mouth or nose, physicians can place Iridium 192, a radioactive source, directly into the esophagus as brachytherapy treatment. Brachytherapy has been used as both primary therapy and following external-beam radiation therapy as a way to “boost” the radiation dose delivered to the cancer. Most radioactive sources are only effective for short distances, so the cancer needs to be of limited thickness for this treatment to be effective.
As primary treatment, brachytherapy has been reported to control local esophageal cancer in 25-35% of patients, which appears similar to the results achieved with external beam radiation therapy. The benefit of adding brachytherapy to external beam radiation and chemotherapy has not been documented.
Complications associated with brachytherapy include perforation, aspiration pneumonia, esophageal bleeding and the development of strictures (narrowing of the esophagus). In one study, the incidence of life-threatening complications was 34% when high doses were administered. Although guidelines have been established by the American Brachytherapy Society, the exact role of this form of treatment for esophageal cancer is currently unclear. Brachytherapy should probably only be administered in the context of a clinical trial or as palliative therapy.
Postoperative Radiation Therapy (Adjuvant Therapy): A recent review of published information concluded that there was no proven survival benefit from administering radiation therapy after surgery, even though some studies showed fewer local recurrences. It is often necessary to consider adjuvant radiotherapy in patients with known microscopic or gross residual tumor after surgery. Post-operative radiation therapy continues to be evaluated in clinical trials.
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