Can I have radiation therapy to the same area twice?

Sometimes, but not always. The National Cancer Institute puts it this way: "There is a limit to the amount of radiation an area of your body can safely receive over the course of your lifetime." NCI adds: "Depending on how much radiation an area has already been treated with, you may not be able to have radiation therapy to that area a second time."

The limit exists because of how radiation works. NCI explains that radiation "kills cancer cells or slows their growth by damaging their DNA," and that it "can also affect nearby healthy cells." Damage to healthy cells is what causes side effects, so the amount an area has already received matters.

Getting radiation again to the same area

The American Cancer Society calls this re-irradiation. It says the decision "depends on the type of cancer, where the tumor is, and how much radiation has already been given to the area." It also says: "If the maximum dose has already been reached, radiation might not be the best option. You may be offered other treatment instead."

NCI adds another route: "if one area of the body has already received the safe lifetime dose of radiation, another area might still be treated if the distance between the two areas is large enough."

What the radiation team looks at

The radiation team decides whether more radiation is the best option. Your earlier treatment records are part of that decision. If your first course was somewhere else, it can help to ask your first hospital for the full radiation record. Ask for the total dose and the area treated.

If the answer turns out to be no, that closes one door and not the rest. You can ask your team what other treatments could be aimed at that spot.