Expect daily weekday treatments for up to six weeks.

Expect daily weekday treatments for up to six weeks.(LARRY DALE GORDON/GETTY IMAGES)In the intimidating trifecta of breast cancer treatmentsurgery, chemotherapy, and radiation—many women find radiation the easiest to deal with. The idea of having a strong dose of radiation beamed at your chest is no one's idea of a good time, but as treatment goes, radiation is relatively painless and side effects are fewer and more manageable than ever before.

If external-beam radiation therapy (the most common kind) is part of your breast cancer treatment, you'll probably have a 20-minute session at a clinic or hospital every weekday for six or seven consecutive weeks. It will go something like this:

Day one
To start off, you'll be measured so that your radiation oncologist and his technicians will know exactly where to aim the radiation beam and how to calibrate the correct dosage. "We do a CAT scan of the breast, heart, and lungs just to see where the structures are," says Jay L. Bosworth, MD, a radiation oncologist with the Nassau Radiologic Group in Manhasset, N.Y., and a Fellow of the American College of Radiology. "And we put tiny tattoo dots—the size of a freckle—on the breast" to ensure the radiation is delivered to the right spot every time.

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The treatment
In the traditional form of the treatment, during the first five weeks, the entire affected breast is usually treated in case any cancerous cells were left behind from surgery and/or chemotherapy. "Then we do a 'boost' [of radiation] in the last week," says Dr. Bosworth, to the area where the tumor was. Other, newer treatments may involve different routines.

Janice Kim, MD, a radiation oncologist at Fred Hutchinson Cancer Research Center in Seattle, notes that if the cancer is in a woman's left breast, an oncologist will take great pains to make sure the radiation steers clear of the heart.

Side effects
You're likely to feel more fatigued as the weeks of radiation treatment go by, and the skin around the area being treated may suffer. You may experience redness, itchiness, dryness, or darkening of the skin. Big-busted women with skin folds under their breasts or armpits are more likely to have peeling, as are patients who had chemo before radiation, since it makes the skin more sensitive. A rare, long-term side effect is weakened rib bones.

Avoid applying creams, powders, or deodorants containing metals, as they can interfere with the treatment. Dr. Bosworth advises patients to stay out of the sun while they're undergoing treatment and for a few months afterward.