Radiation Oncology FAQs

Mercy’s radiation oncology experts use the latest technology to provide the best possible cancer care with compassion and support. Below are answers to some frequently asked questions about radiation treatment. 

Radiation therapy delivers high-energy radiation from x-rays, gamma rays, electron beams and protons to the body to destroy cancer cells and shrink tumors. Therapy can be delivered from a machine outside the body (external beam radiation therapy), or it may come from radioactive material implanted in the body near tumors (internal radiation therapy, or brachytherapy). Systemic radiation therapy delivers radioactive drugs through the blood to tissues throughout the body.

Some people have few or no side effects from radiation therapy, while others may have several. It depends on the type and location of cancer, the radiation dose and your general health.


Commonly reported side effects include fatigue, loss of appetite, hair loss in the treatment area and skin changes (like redness, itching or peeling). Ask your Mercy cancer care team about other possible side effects for your specific type of cancer.

It can take days or weeks of treatment before cancer cells start to die. And the cells may continue dying for weeks or months after radiation therapy ends.

It depends on your individual coverage, and some policies vary by state. For Medicare assistance, call 1-800-MEDICARE (1-800-633-4227) or visit medicare.gov.

More than half of all cancer patients undergo radiation therapy, which is often used to:

  • Destroy small, early-stage tumors
  • Shrink tumors before surgery
  • Stop lingering cancer cells from growing after surgery or other treatments
  • Relieve symptoms of advanced cancer through “palliative radiation,” which shrinks tumors that cause pain, breathing difficulty and other problems
  • Receive primary cancer treatment through radiation therapy
  • Receive radiation therapy combined with other treatments to keep cancer cells and tumors from growing
  • Shrink a tumor before another treatment
  • Stop remaining cancer cells from growing after another treatment
  • Help prevent cancer from returning

Areas of your body can only receive a limited dose of radiation during your lifetime. Depending on how much radiation an area previously received, you might not be able to repeat therapy to the same area again. If one area of your body has already received the safe lifetime dose of radiation, another area might still be treated if there’s enough distance between the two areas.