Radiotherapy is not an unfamiliar word for gastric cancer. Radiotherapy may be used in the adjuvant treatment of postoperative gastric cancer, in inoperable locally advanced gastric cancer, and in the palliative reduction treatment of advanced metastatic gastric cancer. What are the basic principles that physicians will follow in radiotherapy for gastric cancer?
In conjunction with the National Comprehensive Cancer Network (NCCN) guidelines and the Chinese Guidelines for the Standardized Management of Gastric Cancer (2013 version), the following general principles are commonly followed by physicians in radiotherapy for gastric cancer.
- The treatment plan is usually decided after a multidisciplinary team consultation that includes surgeon oncologists, medical oncologists, gastroenterologists, radiation oncologists, radiologists, and pathologists.
- A multidisciplinary team consultation of CT, ultrasound endoscopy (EUS), gastroscopy reports, positron emission computed tomography (PET) or positron emission computed tomography (PET-CT) findings allows the physician to understand the boundaries of the treatment target area and radiotherapy exposure area prior to localization.
- Diagnostic information obtained before the start of treatment is used to determine the target area for radiotherapy.
- For combined gastroesophageal tumors, Siewert type I and Siewert type II tumors are generally treated with reference to the radiation therapy guidelines for esophageal and esophagogastric junction (EGJ) cancer, and for Siewert type III tumors, depending on the situation, the esophageal and EGJ cancer or gastric cancer radiation therapy guideline regimen is considered. The physician will also make changes accordingly depending on the location of the tumor load.
- Imaging may be used to guide enhanced irradiation to the target area, as appropriate. For example, image-guided radiotherapy (IGRT), also known as 4-dimensional radiotherapy, takes into account the movement of tissue during treatment and the differences in location between treatments, thus providing high-dose, high-precision irradiation of the tumor target area while maximizing the protection of surrounding tissue and reducing the probability of radiological complications.
- Synchronous radiotherapy based on cisplatin±fluorouracil and its analogs is usually used, whether pre- or post-operative radiotherapy.
- Postoperative concurrent radiotherapy is usually given for gastric cancer with pathological stage of T3, T4 or N+ without distant metastasis after D0-D1 radical resection (i.e. lymph nodes not cleared beyond station 1); for gastric cancer with pathological stage of T3, T4 or N+ without distant metastasis after standard D2 radical resection (i.e. all lymph nodes cleared at stations 1 and 2), postoperative concurrent radiotherapy is usually given. For gastric cancer with a pathological stage of T3, T4 or with more regional lymph node metastases after standard D2 radical surgery (i.e., all lymph nodes at stations 1 and 2 have been cleared), postoperative concurrent radiotherapy is recommended. In general, patients who underwent R0, R1, and R2 resection received sequentially higher doses of irradiation if they underwent radiotherapy after surgery.
- Patients with local tumor remnants (R1 or R2, i.e., tumor remnants seen microscopically or to the naked eye) from non-radical resection are usually considered by physicians for postoperative local area simultaneous radiotherapy as long as there are no distant metastases.
- For locally advanced inoperable resectable gastric cancer without distant metastases, patients may receive concurrent radiotherapy at an appropriately qualified hospital, if their general condition allows, with the aim of obtaining surgical resectability or long-term control.
- Patients who have had a local recurrence after surgery and are unable to have another surgery may be considered for concurrent radiotherapy if they have not received prior radiation therapy and are physically able to do so. The results are usually evaluated 4 to 6 weeks after radiotherapy to assess whether surgical resection is possible again. If surgery is not possible, local elevated dose radiotherapy with adjuvant chemotherapy is usually indicated.
- For inoperable advanced gastric cancer with vomiting blood, blood in stool, dysphagia, abdominal pain, pain caused by metastases in bone or other sites, which seriously affects the quality of life, if the patient’s physical condition allows, usually simultaneous radiotherapy or radiotherapy alone can play a good role in palliation and reduction of symptoms.
- Patients can receive conventional radiotherapy or be transferred to a qualified hospital for conformal intensity modulated radiotherapy, where the shape of the irradiated area and the dose distribution can be adjusted to the target lesion area.
- Patients requiring postoperative adjuvant radiotherapy should have essentially normal liver and kidney function and blood levels prior to radiotherapy.
The above are some basic principles that doctors will follow when treating patients with gastric cancer with radiotherapy, but the specific clinical application will be tailored to the patient’s specific situation. (Contributed by Xiaowan Chen, Department of Gastrointestinal Oncology, The First Hospital of China Medical University)