Cancer Pain Management


Assistant Professor Sasikarn Chamchod, MD

Faculty of Medicine and Public Health, Radiation Oncology Department, Chulabhorn Royal Academy, Bangkok, Thailand


Two-thirds of patients with metastatic cancer experience pain. Pain can significantly decrease quality of life in cancer patients. Pain may result from tissue damage caused by the tumor, such as bone destruction by a metastasis or direct invasion. Radiotherapy is the most effective oncological treatment of cancer pain. In the treatment of bone metastases, the pain-relieving efficacy of both external radiotherapy and systemic radionuclide therapy is well documented. Radiotherapy is also effective in treating pain caused by soft-tissue tumors, although only a limited number of studies have investigated its efficacy in relieving pain caused by soft-tissue tumors.  The mechanism behind the pain-relieving effect of radiotherapy is incompletely understood. There is no direct correlation between the effectiveness of radiotherapy and the radiosensitivity of the tumor or the dose administered. Tumor shrinkage and inhibition of the release of chemical pain mediators seem to be the main mechanisms by which radiotherapy acts. The rapid onset of pain relief is attributed to the decrease of various chemical pain mediators, whereas tumor shrinkage and recalcification of osteolytic bone lesions contribute to the long-lasting effect. 

Single-fraction treatment (8 Gy) is as effective as a multifraction regimen with 20 Gy in 5 fractions or 30 Gy in 10 fractions. There are no differences between single- and multifraction therapy in the time to initial improvement in pain, time to complete pain relief, or time to first increase in pain at any time up to 12 months from randomization, nor in the class of analgesics used. However, time to treatment failure seems to be shorter after single-fraction treatment. There is no difference in quality of life or side effects between the different fractionation schedules. Acute grade II–IV toxicity seems to be more common among patients receiving fractionated radiotherapy; late toxicity of palliative radiotherapy is rare. 

In a Cochrane analysis, radiotherapy produced complete pain relief in 25% of patients and at least 50% relief in 41% of patients at some time during the trials. The number-needed-to-treat (NNT) to achieve complete relief in one patient at 1 month was 4.2 (95% CI 3.7–4.7).

Event Hours(1)

  • Lotus 5-6

    02:45 pm – 04:00 pm

    1. Assoc. Prof. Chuthamanee Suthisisang (Thailand)
    2. Asst. Prof. Koravee Pasutharnchat (Rama)
    3. Dr. Patt Pannangpetch (CU)
    4. Asst. Prof. Sasikarn Chamchod (CRA)

    Asst. Prof. Pranee Rushatamukayanunt (SI)