The length of your treatment will depend on may factors, including the type of cancer being treated, its stage, how well it is responding to treatment and your own ability to cope with the treatment and its side effects. If you are struggling with severe side effects, your doctor may discuss taking a break to give your body chance to recover before continuing treatment. You may have tests or scans after finishing therapy to see how well the cancer responded to treatment. However, it may take weeks or months to get the full benefit, as radiotherapy continues to work for a while after treatment is finished.