Intraoperative radiation therapy

Intraoperative radiation therapy
Intervention
ICD-9-CM	92.4
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Intraoperative radiation therapy, or IORT is the application of therapeutic levels of radiation to the tumor bed while the area is exposed during surgery. IORT is typically a component in the multidisciplinary treatment of locally advanced and recurrent cancer, in combination with external beam radiation, surgery and chemotherapy. As a growing trend in recent years, IORT can also be used in earlier stage cancers such as prostate and breast cancer.

IORT was found to be useful and feasible in the multidisciplinary management of many solid tumors but further studies are needed to determine the benefit more precisely. Single-institution experiences have suggested a role of IORT e.g. in brain tumors and cerebral metastases, locally advanced and recurrent rectal cancer, skin cancer, retroperitoneal sarcoma, pancreatic cancer and selected gynaecologic and genitourinary malignancies. For local recurrences, irradiation with IORT is besides brachytherapy the only radiotherapeutic option if repeated EBRT is no longer possible. Generally, the normal tissue tolerance does not allow a second full-dose course of EBRT, even after years.

On 25 July the UK National Institute for Health and Care Excellence (NICE) gave provisional recommendation for the use of TARGIT IORT with Intrabeam in the UK National Health Service. The 2015 update of guidelines of the Association of Gynecological Oncology (AGO), an autonomous community of the German Society of Gynecology and Obstetrics (DGGG) and the German Cancer Society includes TARGIT IORT during lumpectomy as a recommended option for women with a T1, Grade 1 or 2, ER positive breast cancer.

The rationale for IORT is to deliver a high dose of radiation precisely to the targeted area with minimal exposure of surrounding tissues which are displaced or shielded during the IORT. Conventional radiation techniques such as external beam radiotherapy (EBRT) following surgical removal of the tumor have several drawbacks: The tumor bed where the highest dose should be applied is frequently missed due to the complex localization of the wound cavity even when modern radiotherapy planning is used. Additionally, the usual delay between the surgical removal of the tumor and EBRT may allow a repopulation of the tumor cells. These potentially harmful effects can be avoided by delivering the radiation more precisely to the targeted tissues leading to immediate sterilization of residual tumor cells. Another aspect is that wound fluid has a stimulating effect on tumor cells. IORT was found to inhibit the stimulating effects of wound fluid.

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