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What is IORT (Intraoperative Radiotherapy)

What is IORT (Intraoperative Radiotherapy)

IORT (Intraoperative radiotherapy) is one of the best techniques used for partial breast irradiation. IORT established as a suitable treatment option for breast cancer. This article will show the clinical trial data, patient selection criteria, advantages and disadvantages of partial breast IORT, and published guidelines.
Doctors use this for selected women with early-stage breast cancer by many clinical trials dating back to the 1990s. Doctors have studied several techniques to fulfill irradiation of the periphery of the lumpectomy bed as sole therapy after lumpectomy.  The major difference between IORT techniques and other forms of APBI is the timing of the procedure.  IORT is most often done at the time of breast cancer surgery as a single dose. Other APBI techniques are performed postoperatively. For these treatments, they typically base target volumes on CT images and deliver multiple fractions. IORT needs specialized radiotherapy equipment. There are several technologies available to arrange IORT partial breast irradiation. And also delivers treatment with either electrons or 50 kV X-rays. 

Advantages of IORT 

  • You will have surgery and radiation at the same time.
  • It is potentially a time saver.
  • It’s only given the radiation for the exact area where the cancer cells are remaining.

Disadvantages of IORT

  • It has a high percentage of occurring cancer again compared to whole breast radiation.
  • Its long-term success rate is good but not similar to whole breast radiation.
  • Its effectiveness is less than whole breast radiation.
  • It has a slight chance of increasing infection after surgery.

Criteria for IORT

Patient selection is important when recommending IORT. As the final pathology is not available at the time of treatment, so to avoid the potential use of subsequent whole breast irradiation, careful pre-operative, and intraoperative assessment can help ensure that high-risk features such as positive margins or positive sentinel nodes will minimize. According to all techniques of the partial breast, irradiation leaves some amount of the breast unirradiated, an understanding of the selection criteria for each of the various techniques is critical information for clinicians when considering which patients may be appropriately treated with IORT or any other APBI (Accelerated Partial Breast Irradiation) technique.


IORT for breast cancer, higher RBE (Relative biological effectiveness) for low-energy X-rays may cause higher tumor control rates in the breast tissue near to the surgical excision bed. And also eliminating the “marginal miss.” Therefore, cell culture data suggest that the RBE decreased at increasing distance, potentially reducing the effective dose to adjacent critical structures including heart and lung. The tumor bed interactively is better oxygenated, which may also promote cell kill probability. 
Besides, there may be also some radiobiological benefits in having a higher dose per fraction in breast cancer, which is estimated to have an alpha/beta ratio of around 4, therefore it may show higher radio responsiveness to higher doses per fraction. The biologically equivalent dose (BED) for an alpha/beta of 4 in the linear-quadratic model for a prescribed single dose of 10 Gy is effective in about 24 in 2 Gy fractions.
Note: (Gy), SI unit of absorbed radiation.


Step 01 – When should Do IORT

The microenvironment of breast cancer cells likely plays a critical role in the risk of tumor recurrence. Therefore, this microenvironment is altered by the use of immediate radiation peri-operatively. First off to check this, test the collected wound fluid from the lumpectomy cavity over 24 hr after surgery, half of whom had IORT at the time of lumpectomy. The wound fluid used to stimulate several breast cancer and control cell lines and analyzed for cell growth and motility. Normal wound fluid stimulated proliferation, migration, and invasion in breast cancer cell lines, while wound fluid canceled these effects from immediately irradiated samples. The radiated wound fluid had altered expression cytokines, suggesting that the radiation had altered protein expression. 

Step 2 – Result Confirmation

Also, collect the tissues from non-irradiated tissue from breast cancer patients after surgery. Then, irradiated using IORT and profiled the tissue for microRNA expression. IORT radiation changed the wound response by inducing expression of miRNA 223 in the peri-tumoral tissue, which downregulated the expression of epidermal growth factor (EGF) and EGF receptor activation. This downregulation cascade prevented breast cancer cell growth. And also reduced local recurrence in mice models. Many other studies have noted the stimulatory effect of wound fluid on breast cancer cells, suggesting a role of the fluid in cancer cell proliferation and possibly local recurrence, an effect immediate radiation may mute that, with its abrogating effect on protein expression.  Therefore, clinical trial data are clinically consistent with these concepts and investigations of the biological effects of immediate high-dose radiation on the wound fluid and immunologic environment are ongoing.


Most people have short-term side effects from radiotherapy treatment, such as skin becomes red, feel Burning (like a strong sunburn) to that area and Feel Tiredness often.
Side effects may develop slowly as the treatment progresses but should disappear within a few weeks of the treatment finishing. Your doctor can give you advice on managing side effects, such as 
  • Apply lotion to relieve dry skin and avoid wearing under-wired bras. 
  • Shave your underarm or using certain deodorants and talcum powder.


Long – term side effects are usually very mild, such as a little hardening bit of the treated tissue, known as fibrosis. However, careful planning, correct positioning at the start of each treatment session, and a good treatment regimen will reduce the chance of this damage to normal tissue.
A few women experience other long-term side effects, but these are not common. For example, they can involve the skin (including a color change), bone, lung, heart or nerves in the treated area. There is also a small risk that radiotherapy can cause new cancer to develop. The side effects experienced will vary from person to person. The techniques now used for radiotherapy allow your doctors to minimize side effects and reduce any risk of damage to the heart. As a result, Lymphoedema is a long-term side effect where the armpit treated by radiotherapy.

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