What Is a Radiation Boost For Breast Cancer?

Woman Receiving Radiation Therapy Treatments for Breast Cancer
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A radiation boost for breast cancer sounds like what it is —a "little extra" radiation dose given after the regular sessions of radiation are complete.  Let's explore this technique in breast cancer therapy, including the research behind its effectiveness, as well as its potential side effects.

Definition of a Radiation Boost

Breast cancer is often treated with surgery, either a lumpectomy or mastectomy. In addition to surgery, other treatments may be given, like radiation therapy, which is treatment with high-energy rays or particles that kill cancer cells. The most common type of radiation therapy given after a lumpectomy (called breast-conserving surgery) is external beam radiation of the whole breast (called whole breast irradiation). 

After your whole breast irradiation treatment sessions are complete, a radiation boost is administered, as a means of preventing a recurrence (the breast cancer coming back). 

More specifically, a radiation boost includes one or more extra treatments targeted at the tumor bed, which is a small area of breast tissue where the original cancer was removed. The tumor bed is targeted because it's the most likely spot where a breast cancer would recur.

This targeted boost dose is given, using the same machine as the one used to radiate the whole breast, but using lower amounts of radiation.

It's important to mention that the tumor bed is best identified at the time of a woman's lumpectomy. This is why surgical clips may be placed at the time of surgery, as these clips help your radiation oncology team focus the radiation beam.

Effect of a Radiation Boost on Breast Cancer Recurrence and Survival

Research has shown that women who undergo a radiation boost have fewer local breast cancer recurrences, as compared to women who do not undergo a boost. Additionally, a reduction in recurrence is greatest in women aged 50 years or younger who are diagnosed with ductal carcinoma in situ (DCIS).

That said, even though a radiation boost significantly reduces the risk of breast cancer recurrence (called a benefit in local control), it does not appear to have any effect on overall survival (up to 20 years out after treatment). 

Side Effects of a Radiation Boost—Short Term and Long Term

A radiation boost is generally tolerated quite well, carrying the same side effects as whole breast radiation, like fatigue, swelling of the breast, and skin changes, like redness, blistering, and peeling, and darkening of the skin. 

That said, in terms of long-term effects, radiation fibrosis of the breast may occur. In fact, one study found that compared to women who did not undergo a radiation boost, those who did were at an increased risk of developing moderate to severe breast fibrosis.

The bottom line here is that the physical appearance of the breast may be worse in women who undergo a radiation boost versus those who do not—although, the research supporting this finding is not robust.

A Word From Verywell

In summary, in women undergoing breast-conserving surgery followed by whole-breast irradiation, a radiation boost is designed to prevent breast cancer recurrence at the tumor site. This boost dose means that an extra dose of radiation is given over the initial tumor site, where microscopic (not visible to the naked eye) cancer cells may be hiding out. 

While a radiation boost has not been found to improve overall survival in women with breast cancer, it does reduce the risk of recurrence, with the largest benefit seen in younger women.

View Article Sources
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