Radiotherapy is one of the common treatments for malignant tumor. Because it is applied to treat malignant tumor, it is referred to as radiation oncology. The primary treatment of malignant tumor consists of radiation oncology, surgical oncology (operation treatment) and medical oncology (chemotherapy). Aside from treating malignant tumor, radiotherapy also treats benign tumor (e.g. pituitary tumor). Currently, radiotherapy is involved in 75% treatment. 45% of malignant tumor is treatable, 22% of which is through operation, 18% is radiotherapy and 5% from chemotherapy.
Purpose of Radiotherapy
Radiotherapy administers precise and a well-distributed dose to certain tumor volume, a few doses affecting surrounding tissue. Thus the tumor can be radically treated with minor damage to the normal tissue. This ensures not only the patient’s survival, but also guarantees quality of life. Radical radiotherapy is the primary objective of radiotherapy, but we cannot ignore the role of palliative treatment, such as analgesia, opening of the pipeline compressed or obstructed by the tumor. Currently, approximately 70% of patients who are treated with radiotherapy are through radical radiotherapy.
Radical radiotherapy refers to a form of therapy by which tumors can be treated after it is given enough dose of radiotherapy resulting in prolonging patients’ lives. The side effect of radiotherapy is inevitable during or after treatment, but it should be controlled within acceptable limits. The purpose of palliative treatment is to relieve symptoms, prolong life and to a certain extent control tumor growth. The doses of radiotherapy are low so that it will not generate serious side effects. Patients’ concerns should be taken into consideration by not increasing their level of discomfort. In some cases where palliative treatment can reduce tumor growth, palliative treatment becomes radical radiotherapy.
Radical Radiotherapy
Radiotherapy is primary option of radical treatment.
Where tumor grows in or near vital organs, operation excision may potentially cause damage to vital organ, or the tumor can only be resected partially. In view of radiation’s sensitivity to tumors, radiotherapy can effectively control or kill tumors, in cases of facial skin cancer, nasopharyngeal carcinoma, head and neck tonsillar cancer, oral cancer and oropharyngeal cancer.
Radiotherapy is one of the main therapies.
Surgical operation is the primary treatment of the most common forms of cancer. At present, the trend of surgical intervention is to reduce primary cancer in order to retain the function of patient’s organ and improve the quality of the patient’s life. As an adjuvant therapy, radiotherapy can be applied before or after operation to improve local control rates of cancer. For example, the effect of radiotherapy in treatment of glottic cancer in its early stage is similar to operation. Five-year survival rate is over 90%. The advantage of radiotherapy is to retain the function of the throat. Even if the radiotherapy fail, operation is just as effective.
Radiotherapy can reduce locally advanced tumors which cannot be resected by operation. For this reason, patients may either accept operation resection or radiotherapy separately or radiotherapy combined with chemotherapy. Its effect is not perfect, but cancer can partially be controlled by radiotherapy. It remains beneficial for patients to prolong their lives or improve the quality of their lives. Examples are; advanced stage cervical cancer, esophageal cancer, lung cancer and breast cancer.
Palliative Radiotherapy
Palliative radiotherapy is applied to patients who suffer from localized and advanced cancer, where operation, radiotherapy and other therapies cannot control cancer, or to patients with distant metastasis of tumor. When modern therapy cannot save cancer patients’ lives and the patients’ clinical symptoms and signs are not obvious, localized treatment is unnecessary. However, if the residual localized tumor cause serious symptoms and signs, radiotherapy should be considered for relief of clinical symptoms and signs caused by cancer. With the purpose of convenient treatment, generally hypofractionated radiotherapy is applied. Large dose 3 ~ 5Gy is given each day, sometimes even higher. A little irradiation should be undertaken within 1~2 weeks. Bone metastasis is the most common indication of palliative radiotherapy. Radiotherapy is beneficial to relieve the pain for bone metastasis, especially osteolytic lesions. Additionally, local radiotherapy for spinal metastasis can prevent paraplegia, while radiotherapy for the vertebral body and limb long bone lesions can prevent pathological fracture.
Intracranial metastatic cancer can cause intracranial pressure increase and central nerve positioning symptoms. Whole brain irradiation should be given often to multiple brain metastases. The amount of radiation should be increased locally. For solitary brain metastatic cancer, whole brain irradiation can be undertaken first, then work with X gamma knife and γ knife.
Radiotherapy can relieve serious clinical symptoms caused by tumor compression, such as superior vena cava syndrome of lung cancer.
Latest Development of Radiotherapy
3D Conformal Radiotherapy and Intensity Modulated Radiotherapy
The ideal effect of radiotherapy is to precisely irradiate tumor itself, but not surrounding tissue of tumor. Although this accuracy has not been fully achieved, radiotherapy has advanced towards an ideal goal because technology of computer and imagelogy has developed rapidly and calculation method of radiation physics dose has improved in 10-20 years. The first to be invented is 3D Conformal Radiotherapy (3DCRT), followed by intensity-modulated radiotherapy (IMRT). IMRT is the advanced stage of 3DCRT. It is suitable for irregular shaped tumors and for tumors interlaced with surrounding normal tissue and organs. Since the 1990s, North America and Europe has undertaken a large number of clinical trials to prove that DCRT and IMRT could improve local control rate and survival rate of cancer, at the same time reduce acute and late-stage complications remarkably. When 3DCRT and IMRT are applied to treat prostate cancer, it improves curative effect, its result similar to operation in early stages of the disease.
Stereotactic Radiotherapy and Stereotactic Gamma Knife Treatment
With the rapid development of computer technology and electronic imaging technology, a special radiation technology emerged: stereotactic radiotherapy. It can be divided into two technologies: γ ray stereotactic radiotherapy technology (also known as gamma knife) and X-ray stereotactic radiotherapy technology (also known as X knife). The principles of these two technologies are relatively the same. The radiation beam is focused on a point which accumulate intense radiation doses in order to treat small malignant and benign diseases. Over the past 10 years, its efficacy and safety have been proven by clinical practice. Its curative effect is much better than conventional radiotherapy technique, especially for central nervous system malignant tumor, benign tumors and benign lesions.
