Intraoperative radiation therapy (IORT)
Intraoperative radiotherapy (IORT) is designed to provide a large radiation dose to a target tissue while sparing normal tissues. The therapeutic advantage is derived by delivering low-energy photons or electrons to a tumor bed with a gross total or near gross total resection, thereby allowing a steep dose fall off, which will spare normal tissues. IORT is often combined with external-beam radiation therapy (EBRT) to provide the best combination of local and locoregional treatment[1][2]. It does, however, require an invasive surgical procedure to locally treat the tumor. It can be used to treat breast, head & neck, pelvic[3], and gastrointestinal[4] malignancies. IORT can be delivered by using Linac-based electron beam radiation therapy (IOERT), low-energy photons, or by high-dose-rate brachytherapy catheters (HDR-IORT). All of these techniques deliver high doses of radiation to the target site while protecting normal surrounding structures through retraction or shielding using lead sheets[5].
These procedures are resource intensive and require complex patient selection and logistical planning. An IORT program requires the combined planning and efforts of surgical and/or medical oncology, radiation oncology, OR staff, and anesthesiology.
| Anesthesia type |
General |
|---|---|
| Airway |
ETT |
| Lines and access |
PIV x2 +/- Arterial line +/- Central line |
| Monitors |
Standard BIS +/- ABP +/- CVP |
| Primary anesthetic considerations | |
| Preoperative |
Frailty, chemotherapy sequelae (pancytopenia), tumor size and location, "full stomach" |
| Intraoperative |
Access, resuscitation, equipment contingencies |
| Postoperative |
Potential ICU transport, ongoing resuscitation |
| Article quality | |
| Editor rating | |
| User likes | 0 |
Overview
Indications
- Subtotal resection of malignancy
- Recurrent malignancy for which external beam radiation is deemed unsafe
Surgical procedure
The basic principles are well described by Debenham et al[1]
Resection
The first step is total or sub-total resection of tumor
- Whether the tumor is large or small, the IORT equipment usually requires a large laparotomy
- Each tumor is different and will carry distinct risks in terms of bleeding potential, compression of vital structures, invasion of large vessels
Intraoperative Radiation
The next step is positioning the radiation equipment
- The radiation oncology team decides on technique, dose, and equipment
- Some equipment require special lead shielded rooms or other radiation barriers, while others are self shielding
- Generally once the equipment is positioned correctly, everyone must leave the room during treatment so as not to be exposed to radiation. Treatment times vary, but are usually 5-10 minutes. Confirm with the surgeon and radiation oncologist how long they plan on treating
- Every institution approaches monitoring during this time differently, some use cameras, some place monitors at windows, some have shielded subrooms in the OR
- Whatever approach is used, the goal is to have the patient in a steady, stable state at the time of treatment. If you are not in a stable state, inform the surgical team that you need to stabilize the patient prior to proceeding with treatment
- Discuss with the surgeon, radiation oncologist, and physicists what the protocol is for ending treatment and re-entering the room in case of emergency. Generally, the radiation equipment can be turned off quickly and once turned off it is safe to enter the room
Closure
The final step is finalizing any remaining surgical procedures and closure
Preoperative management
Patient evaluation
| System | Considerations |
|---|---|
| Airway | Large abdominal tumors or patients with ascites may require RSI |
| Neurologic | Neoadjuvent chemotherapy or radiation can cause neuropathy |
| Cardiovascular | Standard evaluation |
| Pulmonary | Standard evaluation |
| Gastrointestinal | Tumor size, location, possible compression or invasion of other structures |
| Hematologic | Pancytopenia in setting of chemotherapy |
| Renal | Standard evaluation |
| Endocrine | Standard evaluation |
Labs and studies
- Type and screen - cross units depending on patient and procedure
- CBC
- +/- EKG, TTE, stress test
- Otherwise indicated by history and presentation
Operating room setup
- Arterial catheter and transducer
- Fluid warmer
- Infusion pumps
- Vasopressor infusions available
- Push dose pressors
- +/- blood tubing
Patient preparation and premedication
- Standard
Regional and neuraxial techniques
- Useful for multimodal pain control
- Epidurals are frequently used for intraoperative autonomic control and postoperative pain control for abdominal or thoracic tumors
- If epidural contraindicated, regional blocks can be used for postoperative pain control
Intraoperative management
Monitoring and access
- PIV x2
- Standard monitors
- Frequently radial arterial line
- Central line as indicated by tumor and patient
Induction and airway management
- Standard
- For abdominal tumors cosider RSI
Positioning
- Standard, depends on tumor location and planned procedure
Maintenance and surgical considerations
- Standard maintenance, patient is chemically paralyzed to assist with adequate surgical exposure and ensure immobility during radiation treatment
- IORT procedures are highly variable in terms of tumor size, position, vascularity, etc. and, therefore, need to be approached on a case by case basis in terms of planning induction, intubation, access, and blood product preparation
- Review imaging and discuss with surgeons their expectation for the extent of resection and possible difficulties to help guide your decisions about access and preparation
- Stay in communication with the surgery team about timing of the radiation treatment as well as the expected length of treatment
- The goal is to reach a steady state as they are arming and positioning the radiation equipment so that the patient can be left alone for 5-10 minutes
- As an extra precaution, you can connect a few extension tubings and thread that line into the shielded area in order to administer medication if needed
- Position the monitors so that they can be seen from the shielded area, consider being able to see two monitors in case one fails
Emergence
- Standard
Postoperative management
Disposition
- Depends on patient and surgical factors, but usually stepdown, occasionally ICU or floor
Pain management
- Depends on tumor location and size
- For abdominal tumors, usually large incision, painful procedure
- Neuraxial or regional pain control always, unless contraindicated
- Multimodal pharmacologic pain control
Potential complications
- IORT itself carries very low intraoperative and immediately postoperative complications
- Most complications are related to the tumor resection itself
- For large or vascular abdominal tumors concerns include:
- Aspiration
- IVC compression
- Hemorrhage due to bleeding of tumor or damage to surrounding vessels during resection
- Standard general anesthetic and operative complications
References
- ↑ 1.0 1.1 Debenham, B. J., Hu, K. S., & Harrison, L. B. (2013). Present status and future directions of intraoperative radiotherapy. Lancet Oncology, 14(11), e457-64. doi:https://doi.org/10.1016/S1470-2045(13)70270-5
- ↑ Christopher G. Willett et al. Intraoperative Radiation Therapy. J Clin Oncol 25, 971-977(2007).DOI:10.1200/JCO.2006.10.0255
- ↑ Roth TM, Secord AA, Havrilesky LJ, et al. High dose rate intraoperative radiotherapy for recurrent cervical cancer and nodal disease. Gynecol Oncol. 2003;91:258–260. doi: 10.1016/s0090-8258(03)00443-8.
- ↑ Alfieri S, Morganti AG, Di Giorgio A, et al. Improved Survival and Local Control After Intraoperative Radiation Therapy and Postoperative Radiotherapy: A Multivariate Analysis of 46 Patients Undergoing Surgery for Pancreatic Head Cancer. Arch Surg. 2001;136(3):343–347. doi:10.1001/archsurg.136.3.343
- ↑ Moningi S, Armour EP, Terezakis SA, Efron JE, Gearhart SL, Bivalacqua TJ, Kumar R, Le Y, Kien Ng S, Wolfgang CL, Zellars RC, Ellsworth SG, Ahuja N, Herman JM. High-dose-rate intraoperative radiation therapy: the nuts and bolts of starting a program. J Contemp Brachytherapy. 2014 Mar;6(1):99-105. doi: 10.5114/jcb.2014.42027. Epub 2014 Apr 3. PMID: 24790628; PMCID: PMC4003434.
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