Radiation Therapy Principles

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Other general health concerns

Many patients want to know how they can improve their general health to help their body’s natural defenses fight the cancer. They may also want to do things to speed up their recovery from radiation’s side effects.

Quitting smoking

For patients who still smoke, it’s never too late to quit. Studies show that people with some types of cancer who keep smoking during and after treatment have a greater risk of the cancer coming back and of new cancers forming. Smoking can increase many side effects, too. It can also reduce appetite at a time when extra nutrition is needed. For help quitting smoking, please see our Guide to Quitting Smoking or call us at 1-800-227-2345.


You may need to avoid certain foods because of your treatment, but eating a balanced diet is important. It’s also important to take in enough calories to provide energy for healing. If you’re having trouble getting enough nutrition or are worried about what types of food you should be eating, ask your doctor about a referral to a dietitian. You may also want to see our document called Nutrition for the Person With Cancer During Treatment: A Guide for Patients and Families.

Patients should check with their doctors before taking any vitamins or supplements on their own during radiation treatment. Certain vitamins, such as A, E, and C act as antioxidants. They help keep ions (electrically charged particles) that damage DNA in cells from forming. This damage is thought to have an important role in causing cancer. There is some evidence that getting enough antioxidants might help reduce the risk of getting some types of cancer. But during treatment, radiation therapy works to fight cancer by producing these ions, which severely damage the DNA of cancer cells. Some scientists believe that taking high doses of antioxidants, including certain vitamin and mineral supplements, during treatment may make radiation therapy less effective by reducing this particular way of damaging cancer cells. So far, studies have not fully tested this theory. While this is being researched, many radiation oncologists recommend the following:

  • If your doctor has not prescribed vitamins for a specific reason, it’s best not to take any on your own.
  • A single multivitamin tablet each day is probably OK for patients who want to take a vitamin supplement, but check with your doctor first.
  • It’s safest to avoid taking high doses of antioxidant vitamins or other antioxidant supplements during treatment. Ask your doctors when it might be safe to start such vitamins or supplements after treatment is finished.

Last Medical Review: 10/23/2013
Last Revised: 10/23/2013