Strategy of radiation therapy for bone metastases and MSCC in breast cancer patients.

Bone metastasis is a common event in advanced cancers such as prostate, breast, lung, and renal cancers. Radiation therapy has been widely used for bone metastasis. However, it remains a challenging therapy because no radiation therapeutic guidelines, including radiation dose, radiation field, and fractionation, for patients with bone metastasis have been established. Many randomized controlled trials for bone metastasis have been carried out. They showed no significant difference in pain relief with a short course of radiation therapy such as 8 Gy/1 Fr and 20 Gy/5 Fr or with a long course of radiation therapy such as 30 Gy/10 Fr, 37.5 Gy/15 Fr, and 40 Gy/20 Fr. Toxicity rates with short and long courses were also the same. Recurrence rate at 2 years, however, was significantly higher in patients irradiated with a short course than in patients irradiated with a long course. Those trials also showed that response rate is affected by patient's age, performance state, tumor type, pathological state, number of metastatic tumors, and span from diagnosis of cancer to development of metastatic tumor. Breast cancer has a better prognosis than most other cancers. Recently, there have been significant advances in cancer therapy techniques and improvement in clinical results. Bone metastasis can cause extreme pain and motor deficits. Quality of life for patients with bone metastasis is drastically worsened. Patients with bad prognosis should be treated with radiation therapy when analgesia is the main aim of treatment. Survival of patients with oligometastasis or predominantly bone metastasis is expected to be better than that of patients with visceral metastasis. For patients with vertebral or weight-bearing long bone metastasis, long-course therapy is recommended. Many patients who are expected to have a good prognosis should be treated with a long course of radiation.