Radiation therapy is a common cancer treatment that uses high-energy radiation to destroy cancer cells. Although the treatment is targeted, it can also affect healthy tissue in and around the treated area, which may cause pain both during and after the course of treatment. Most patients experience only mild discomfort, but some develop more significant or long-lasting pain.

Acute pain
During treatment, radiation can irritate the skin and mucous membranes in the irradiated area, often causing redness, swelling, tenderness, or burning sensations. When the skin is affected, it is called radiation dermatitis, and when the mucous membranes are affected, it is called mucositis. Radiation to the head, neck, or chest area can, for example, make it painful to eat, swallow, or touch the skin. These acute side effects typically appear within the first few weeks of treatment and gradually subside after radiation therapy ends.

Late side effects
Some side effects may not appear until months or years after treatment. Radiation can cause fibrosis, where the tissue becomes stiff and less elastic, or nerve damage, which can lead to persistent pain, numbness, or hypersensitivity. Some patients develop chronic pain in the muscles, joints, or bones within the irradiated area. In rare cases, radiation near the spine can cause neuropathic pain, depending on the dose and treatment area.

Pain after radiation therapy varies greatly between patients and can be difficult to predict. It is therefore important to pay attention to new or worsening pain - even long after treatment has ended.