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What Is Intraoperative Radiation Therapy?

Intraoperative radiation therapy is radiation treatment delivered directly to a tumor or surgical tumor bed while an operation is in progress. It is commonly abbreviated IORT. After the surgeon removes or exposes the target, surrounding normal tissues can be moved or shielded so a concentrated radiation dose reaches the area at greatest risk for residual microscopic disease. IORT can use electrons, low-energy X-rays, or other specialized radiation-delivery systems depending on the cancer center and clinical indication.

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What Is Intraoperative Radiation Therapy?

Intraoperative radiation therapy is radiation treatment delivered directly to a tumor or surgical tumor bed while an operation is in progress. It is commonly abbreviated IORT. After the surgeon removes or exposes the target, surrounding normal tissues can be moved or shielded so a concentrated radiation dose reaches the area at greatest risk for residual microscopic disease. IORT can use electrons, low-energy X-rays, or other specialized radiation-delivery systems depending on the cancer center and clinical indication.

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Why Is Intraoperative Radiation Therapy Performed?

IORT is used in selected cancers when delivering radiation directly during surgery can improve local treatment while limiting dose to nearby normal structures. It has been used in breast cancer, sarcoma, colorectal and pelvic cancers, pancreatic cancer, and other selected tumors, although the strength of evidence and standard indications differ by disease. In some settings it serves as a radiation boost in addition to external-beam treatment, while in carefully selected early breast cancers it can be used as a form of accelerated partial-breast irradiation. Treatment decisions depend on tumor type, surgical margins, previous radiation, anatomy, recurrence risk, and the availability of specialized equipment and expertise.

How Is Intraoperative Radiation Therapy Performed?

The surgeon first removes or exposes the tumor and prepares the treatment field. Sensitive organs, nerves, bowel, skin, or other structures are moved away or shielded whenever possible. A radiation applicator is positioned directly against or very close to the target, and the radiation oncology team delivers the prescribed dose while the patient remains under anesthesia. After treatment is completed, the applicator and shielding are removed and the surgeon finishes the operation and closes the wound.

What Is Recovery Like After Intraoperative Radiation Therapy?

Recovery is primarily determined by the underlying surgery because IORT is delivered during the same anesthetic session. The surgical team monitors wound healing, pain, infection, organ function, and any early radiation effects in the treated region. Some patients still require external-beam radiation, chemotherapy, endocrine therapy, or other cancer treatment after they recover from surgery. Follow-up focuses on local tumor control, wound or tissue changes, and delayed radiation effects that can appear months or years later.

What Are the Risks and Complications?

IORT can cause radiation injury to normal tissue within or near the treatment field even though surrounding structures are moved or shielded when possible. Potential complications include delayed wound healing, fibrosis, tissue necrosis, neuropathy, pain, bone injury, or organ-specific effects depending on the treated area. The combined procedure can also increase operative complexity and prolong anesthesia in some settings. Late complications vary by radiation dose, tissue sensitivity, prior radiation exposure, surgical technique, and the specific cancer being treated.

Frequently Asked Questions About Intraoperative Radiation Therapy

Is IORT given while the patient is still in surgery?

Yes. Radiation is delivered directly to the exposed tumor or tumor bed during the operation while the patient remains under anesthesia.

Does IORT replace external-beam radiation therapy?

Sometimes, but not usually. In many cancers it is used as a boost with external-beam radiation, while selected early breast-cancer protocols can use it as a focused partial-breast treatment.

How are normal organs protected during IORT?

Surgeons can move sensitive tissues away from the field or place shielding between normal structures and the radiation applicator before treatment begins.

What cancers can be treated with IORT?

IORT has been used for selected breast, sarcoma, colorectal, pelvic, pancreatic, and other tumors, but its role and evidence vary substantially by cancer type.

References

Definition of intraoperative radiation therapy. National Cancer Institute. https://www.cancer.gov/publications/dictionaries/cancer-terms/def/intraoperative-radiation-therapy. Date Accessed September 11, 2026.

The American Brachytherapy Society consensus statement on intraoperative radiation therapy. PubMed. https://pubmed.ncbi.nlm.nih.gov/31084904/. Date Accessed September 11, 2026.

ESTRO IORT Task Force/ACROP recommendations for intraoperative radiation therapy with electrons (IOERT) in breast cancer. PubMed. https://pubmed.ncbi.nlm.nih.gov/32413529/. Date Accessed September 11, 2026.

The role of intraoperative radiation therapy in resectable pancreatic cancer: a systematic review and meta-analysis. PubMed. https://pubmed.ncbi.nlm.nih.gov/32272945/. Date Accessed September 11, 2026.

A Comprehensive Meta-Analysis and Review of Intraoperative Radiotherapy in Colorectal Cancer: Examining Radiation Dosage, Long-Term Prognosis, and Treatment-Related Complications. PubMed. https://pubmed.ncbi.nlm.nih.gov/42522172/. Date Accessed September 11, 2026.