Timothy Moynihan, M.D., Mayo Clinic oncologist

As part of the standard treatment for breast cancer, we have a choice to do two things. Either remove the entire breast, in which case we usually do not need to use radiation therapy as a part of it. If, however, we just remove the lump, then radiation therapy becomes an important part of that to try and prevent the breast cancer from coming back in that local region.

Now after we've removed the lump, there's no cancer that we can see. As far as we know, your body is cancer-free at that time. But we know from past experience there's a significant risk for the cancer to come back locally in that region. This is when we use adjuvant radiation.

Now adjuvant is the term used when we're giving treatment when we have no visible signs of the disease left. So it's very important to use it in this setting in order to decrease the chance of it coming back.

That contrasts with primary radiation, where primary radiation is where we have a tumor that we can see either on scan or in physical exam that we're treating to try and shrink it. And that's primary radiation, and that is a different setting because we can actually watch the effects of the radiation as it shrinks the tumor. Whereas in the adjuvant setting, we have nothing that we can watch, we're just using it to try and prevent future recurrences.

VIDEO HELP

If the video does not play, you may need to download and install the latest version of the Adobe Flash Player. For additional troubleshooting tips, browse the Multimedia FAQ.