Breast Cancer Treatments/Surgeries and Radiation

IORT vs. Traditional Radiation for Breast Cancer

Medically reviewed by Maybell Nieves, M.D.

Written by Vanessa Ling, ND, CNS

Posted on October 27, 2026

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Key Takeaways

Intraoperative radiation therapy, or IORT, is a type of radiation that can be delivered directly to the tumor site during lumpectomy surgery, and it may be an option for some people with early-stage breast cancer.
IORT and traditional radiation therapy have similar survival rates, but studies show that breast cancer is more likely to return in the same breast after IORT alone, with one 2021 review finding that people who had IORT were about twice as likely to experience a recurrence compared to those who had whole-breast radiation. Because IORT targets a smaller area, it tends to cause fewer skin-related side effects than traditional radiation, though it may be more likely to affect fat tissue in the breast or cause calcium deposits in scar tissue.
If you are curious about whether IORT might be right for you, talking with your surgeon and radiation oncologist is a great first step, as they can help you understand your options based on your specific diagnosis, tumor size, and overall health, and they can also help you look into whether IORT is available at your treatment center and whether your insurance may cover it.

View all takeaways

Intraoperative radiation therapy (IORT) is a type of radiation therapy that can be done during lumpectomy surgery in certain cases. For some people with early breast cancer, IORT may be more convenient and have fewer side effects than traditional radiotherapy. However, there are limits to who might benefit from IORT and where it’s available.

We’ll cover how IORT works, when it might be recommended, and how it compares to traditional radiation therapy.

How Does IORT Work?

In general, radiation therapy is often given after a lumpectomy to kill any cancer cells remaining in the breast after surgery (microscopic disease). These cells may not be detectable, so radiation therapy helps to lower the chance of cancer coming back.

🗳️ Were you offered intraoperative radiation therapy (IORT) as part of your breast cancer treatment plan?

Yes, and I used IORT

Yes, but I didn’t use IORT

No, I was only offered traditional radiation therapy

No, I wasn’t offered any type of radiation therapy

In IORT, one large dose of radiation is delivered directly to the area where the tumor was removed, called the tumor bed. It’s given as a single dose of radiation so the person doesn’t have to come back for traditional external radiotherapy.

For this reason, some MyBCTeam members refer to IORT as a “one and done” treatment.

In some cases, IORT may also be given as a boost, or an extra dose to the tumor bed that is followed by external radiation to the whole breast.

Who Is IORT Recommended For?

IORT is generally considered for people with early-stage breast cancer who are having a lumpectomy and have a lower risk of the cancer coming back.

Whether you’re a candidate depends on factors such as the stage of your breast cancer, the size and location of your tumor, your overall health, and whether your cancer center offers the treatment.

For example, Columbia University’s breast surgery team offers IORT to most people with early-stage breast cancer whose tumors are 2 centimeters or smaller and who are eligible for a lumpectomy. Guidelines on when to offer IORT may differ between cancer centers that perform it.

IORT may also be considered for people who can’t have traditional radiation or those who would have trouble getting to weeks of daily treatment, for instance, those who live far from a radiation center. However, those factors alone aren’t enough to make someone a candidate for IORT.

Current Guidelines for IORT

IORT isn’t currently the standard of care for most people with breast cancer. Current guidelines from the American Society for Radiation Oncology (ASTRO) don’t recommend IORT on its own after a lumpectomy unless it’s a part of a clinical trial.

The American Cancer Society (ACS) also notes that more research is needed to understand who benefits most from IORT.

IORT vs. Traditional Radiation

Traditional radiation is also called external beam radiation therapy (EBRT). This involves aiming a beam of radiation at the affected breast from outside the body. It requires multiple sessions to complete.

Traditional radiation therapy starts after the lumpectomy surgery wounds are healed, which can take about a month. EBRT can be given five days a week for three to six weeks, depending on the area affected and the type of EBRT recommended for you. In select cases, radiation therapy can be given in five treatments over one week.

In comparison, IORT is given once, during your lumpectomy surgery, and treats only the area where the tumor was removed. Your oncology providers give radiation to the area using a machine called a linear accelerator.

Effectiveness of IORT vs. Traditional Radiation

IORT and traditional radiation lead to similar survival rates, but breast cancer is more likely to come back in the breast treated after IORT alone.

Studies measure overall survival, the percentage of people still alive a certain amount of time after diagnosis, and local recurrence, how often cancer returns in the same area after treatment.

A 2021 review of clinical trials found that people treated with IORT were about twice as likely to have cancer return in the same breast compared with those who received whole-breast radiotherapy. The study showed no difference in overall survival between the groups.

In a study published in 2025, cancer came back in the same breast within five years in about 5 percent of people who got IORT alone. In comparison, about 1 percent of those who also had additional radiation therapy to the whole breast experienced a recurrence of cancer in the same breast. In the same study from 2025, women 65 and older with certain tumors had a 2 percent recurrence rate.

Based on these findings, researchers recommend that breast cancer specialists choose candidates for IORT carefully.

Side Effects of IORT vs. Traditional Radiation

Because IORT targets a smaller area, nearby healthy tissues are exposed to less radiation. The surgical team uses special shields to protect healthy parts of your body.

Common side effects of IORT are limited to the breast area. These include:

Slow wound healing at the surgical/IORT site
Scar tissue
Infection
Skin irritation
Fluid or blood collecting under the skin

In comparison, traditional radiation may have both local and whole-body side effects. These can include:

Breast swelling
Skin changes that look like a sunburn, such as skin discoloration or redness, peeling skin, or darkened skin
Sun sensitivity
Extreme tiredness
Temporary breast changes, including swelling, increased firmness, or a decrease in breast size

In trials that compared the two treatment options, those who had IORT were less likely to have skin side effects than those who had traditional radiation. However, IORT was more likely to damage fat tissue in the breast, cause breast swelling, and lead to calcium deposits in scar tissue.

Rates of pain, lung scarring, and fluid buildup were similar between the two treatments.

When Is IORT Not Recommended?

IORT may not be recommended under certain circumstances. Your cancer care team may consider:

The size of your tumor
The stage of your cancer
Whether cancer cells are found in your lymph nodes
Your age
The availability and cost of the treatment

For larger tumors or cancer that has spread to the lymph nodes, doctors may consider traditional radiation therapy because of the higher risk of recurrence. One study concluded that IORT should only be offered to certain people who have a low risk of breast tumor recurrence.

IORT and other types of partial breast radiation only target a small area of the breast. According to the current guidelines, these treatments may be an option through clinical trials for women over 40 with early-stage cancer who have breast tumors smaller than 2 centimeters and no cancer in their lymph nodes.

Access to IORT May Be Limited

IORT also isn’t available at every cancer center because it requires specific equipment and specially trained teams. Not all insurance companies cover IORT, which can become a barrier for some people.

“I’m supposed to have surgery this week, and my insurance is dragging its heels on approving the lumpectomy and IORT. Now they’ve decided that peer-to-peer IORT review is necessary.”

— A MyBCTeam member

Talking to Your Care Team About IORT for Breast Cancer

Choosing a type of radiation therapy after a lumpectomy is a decision best made in partnership with your cancer care team. Your surgeon and radiation oncologist can explain why they’re recommending IORT or traditional radiation based on individual factors like your tumor size, type of breast cancer, and your overall health.

You can start the conversation by asking whether IORT is offered where you’re being treated, whether your insurance covers it, and how likely you are to need more radiation after surgery.

Your care team can also help you understand what to expect during and after your treatment, including side effects and how to manage them safely. Ultimately, these discussions can help you weigh the risks and benefits of IORT and help you make an informed decision.

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