Radiation Therapy
Radiation therapy — also called radiotherapy — is a treatment used to kill cancer cells and shrink tumors.
The radiation treatment procedure is painless, but it may cause some skin discomfort over time. When treating early-stage breast cancer, radiation therapy is often given after surgery. Surgery is done to remove the cancer, and radiation is done to destroy any cancer cells that may remain after surgery. This helps lower the risk of the cancer coming back (recurrence).
Radiation therapy also can be used to treat:
breast cancer that can’t be removed with surgery, which doctors call unresectable
metastatic breast cancer, which is breast cancer that has spread to parts of the body away from the breast, such as the bones, lungs, brain, or liver
How does radiation therapy work?
Radiation therapy uses special high-energy X-rays or particles to damage a cancer cell’s DNA. When a cancer cell’s DNA is damaged, it can’t divide successfully and it dies.
Radiation therapy damages both healthy cells and cancer cells in the treatment area. Still, radiation affects cancer cells more than normal cells. Cancer cells grow and divide faster than healthy cells and also are less organized. Because of this, it's harder for cancer cells to repair the damage done by radiation. So cancer cells are more easily destroyed by radiation, while healthy cells are better able to repair themselves and survive the treatment.
The treatment area may include the breast area, the lymph nodes, or another part of the body if the cancer has spread.
Radiation treatments are carefully planned to make sure you receive the greatest benefits and the fewest side effects possible.
Types of radiation therapy
There are two main types of radiation therapy used to treat breast cancer: external beam radiation therapy and brachytherapy, or internal radiation therapy. Intraoperative radiation therapy and proton therapy are also available, but not used as widely as the other two types.
External beam radiation is given by a large machine called a linear accelerator. The machine aims a beam of radiation at the treatment area.
There are three special types of external beam radiation:
Proton therapy or proton beam therapy, uses particles called protons rather than X-rays to treat cancer. Proton therapy for breast cancer is not the standard of care, is still being studied, and is not available at all treatment facilities.
Stereotactic radiation therapy, also called by certain brand names, such as Gamma Knife or Cyberknife, can used to treat spots of metastatic disease, including in the brain or spine. It delivers a high dose of radiation using several precisely focused beams to a small, well-defined area.
Intraoperative radiation therapy delivers the entire course of radiation at one time during breast cancer surgery. It’s only available at certain facilities.
Internal radiation, called brachytherapy by doctors, uses a radioactive substance sealed in seeds or tiny tubes that are placed inside your body directly into the cancer or the place where the cancer was.
Radiation therapy can be used to treat all stages of breast cancer.
The timing of radiation treatment in your overall breast cancer treatment plan depends on your individual situation and the characteristics of the breast cancer. In many cases, radiation therapy is given after surgery. If chemotherapy is planned after surgery, radiation usually follows chemotherapy.
Radiation therapy is recommended for most people who have lumpectomy to remove breast cancer. Lumpectomy is sometimes called breast-conserving surgery. The goal of radiation after lumpectomy is to destroy any individual cancer cells that may have been left in the breast after the tumor was removed. This reduces the risk of the cancer coming back (recurrence).
Here’s a good analogy for understanding the role of radiation therapy after surgery: “If you drop a glass on the kitchen floor, you must first sweep up all of the big pieces of glass and throw them away — you can think of breast surgery in this way,” says Marisa Weiss, MD, founder and chief medical officer of Breastcancer.org and director of breast radiation oncology at Lankenau Medical Center. “Radiation therapy is like vacuuming the area after you sweep, getting into the corners and under the furniture, to get rid of any tiny shards of glass that might be left behind.”
Still, to personalize treatments to everyone’s unique situation, researchers continue to study whether there are certain types of breast cancer that may not need radiation therapy after lumpectomy. A 2023 study suggested that certain older women diagnosed with breast cancer with a very low risk of recurrence could take only hormonal therapy and skip radiation therapy after lumpectomy.
Radiation therapy may be recommended after mastectomy to destroy any cancer cells that may be left behind after the surgery. During mastectomy, it's difficult for surgeons to take out every cell of breast tissue.
Your doctor will look at your pathology report and calculate your risk of breast cancer recurrence based on a number of factors, including:
the number of lymph nodes involved
the size of the cancer
if cancer is at any of the edges of the surgery (positive margins)
If you have a high risk of recurrence, your doctor may recommend radiation after mastectomy to the area where the breast tissue used to be and sometimes to the nearby lymph node areas.
Full-dose radiation is usually given only once to a particular part of the body. Your normal tissues can only tolerate a limited amount of radiation. Still, research has shown that repeat radiation with full doses to the same area may be possible in some situations. 1
If you’re going to have radiation again in the same area, your radiation oncologist knows how to pick the right dose of radiation to accomplish two things:
reach the maximum therapeutic dose — the amount that's likely to destroy cancer cells
avoid or minimize side effects to the normal tissue
If cancer returns to the same area in the breast, you may or may not be able to receive a limited amount of additional radiation treatment in that same area. Your doctor will know what the limits are, and together you can decide if this is a good treatment option for you.
It's important to note that this information refers to treating the same part of the body a second time. If cancer occurs in another part of your body (including the other breast), a full dose of radiation can be used.
Who can’t get radiation therapy?
Radiation therapy for breast cancer is not an option if:
you have a connective tissue disease, such as scleroderma, which makes you extra-sensitive to the side effects of radiation
you are pregnant, since radiation can harm the fetus
you can’t commit to the daily schedule of radiation therapy, or distance makes it impossible
Radiation therapy and breast reconstruction
If you’re having mastectomy followed by breast reconstruction, it’s important to know that radiation can cause a reconstructed breast to lose volume and change color, texture, and appearance.
In particular, radiation therapy is known to cause complications with implant reconstruction. Research also suggests that, in some cases, a reconstructed breast may interfere with radiation therapy reaching the area affected by cancer.
For these reasons, many surgeons advise waiting until after radiation and other treatments, such as chemotherapy, are completed before breast reconstruction surgery is done.
Other surgeons may recommend a more staged approach. This involves placing a tissue expander after mastectomy to preserve the shape of the breast during radiation treatments. Once radiation is completed and the tissues have recovered, the expander is removed and replaced with either a breast implant or tissue from another part of the body.
Radiation therapy side effects
The side effects of radiation therapy depend on the type of radiation therapy you’re having. In general, the side effects tend to develop as treatment goes on and may be more troubling toward the end of treatment. Overall, the most common side effects are redness, swelling, and skin peeling in the area being treated.
Learn more about radiation side effects.
Radiation for metastatic breast cancer
If you’ve been diagnosed with metastatic breast cancer and are having symptoms, your doctor may recommend radiation therapy to:
ease pain
lower the risk of a cancer-weakened bone breaking
decrease bleeding
open a blocked airway to improve breathing
reduce pressure on a pinched spinal cord or nerve that might be causing pain, numbness, or weakness
treat cancer that has spread to the brain
The radiation dose and schedule to treat metastatic breast cancer depends on a number of factors, including:
the level of pain or amount of function lost
the size of the cancer
the location of the cancer
the amount of previous radiation you’ve had
the schedule for any other treatments
Learn more about radiation for metastatic breast cancer.
Vitamins to avoid during radiation therapy
Your radiation oncologist may tell you to avoid taking certain antioxidant vitamin supplements, such as vitamins C, A, D, and E, while you're having radiation therapy. These vitamins might interfere with radiation's ability to destroy cancer cells. This is because radiation works in part by creating free radicals — highly energized molecules that damage cancer cells. Free radicals in the environment can damage all cells, but in the case of radiation treatment they are focused on the cancer cells. Antioxidants help keep free radicals from forming or neutralize them if they do form.
Because of the potential conflict between the goal of radiation therapy (to make free radicals) and the goal of antioxidants (to neutralize free radicals), it makes sense to stop taking any antioxidant supplements during radiation therapy. When radiation is finished, you can resume taking your supplements.
Throughout your treatment, do your best to eat a well-balanced diet that contains all of the vitamins you need. Vitamins that come naturally from food are unlikely to interfere with treatment.
Radiation therapy and sun exposure
During radiation treatment, it’s best to keep the treated area completely out of the sun. This can be especially difficult if you’re having radiation therapy in areas or seasons with warmer weather. To help avoid sun exposure:
Wear clothing or a bathing suit with a high neckline, or wear a rash guard top.
Try to keep the area covered whenever you go outside. An oversized cotton shirt works well and allows air to circulate around the treated area.
Avoid chlorine, which is very drying and can make any skin reactions you’re having worse. Chlorine is used to disinfect most pools and hot tubs.
If you do want to swim in a pool, you might want to spread petroleum jelly on the treated area to keep the chlorine away from your skin.
After your radiation treatment is completed, the treated skin may be more sensitive to the sun than it was in the past, so you might need to take extra protective steps when you go out in the sun:
Use a sunblock rated 30 SPF or higher on the area that was treated.
Apply the sunblock 30 minutes before you go out in the sun.
Reapply the sunblock every two hours, as well as when you get out of the water.
Arthur DW, et al. JAMA Oncol. Nov. 21, 2019. Available at https://pubmed.ncbi.nlm.nih.gov/31750868/
— Last updated on December 12, 2024 at 9:28 PM
