IORT: Treating cancer with internal radiation therapy
September 16, 2020
Radiation has been used to shrink and destroy cancerous tumors for decades. While most people think of radiation being projected from a machine outside the body, doctors have been using brachytherapy – an internal form of radiation – to treat hard to reach tumors for far longer.
Brachytherapy was first used in the early 1900s to treat prostate cancers. Early iterations involved directing an applicator containing a sealed radioactive substance (radium) through an existing orifice into the tumor site by hand.
Techniques improved through the decades, and by the 1980s advanced into the development of the seed-based radiation we use today. Now, we can treat nearly any site in the body with brachytherapy using minimally invasive approaches and precise image guidance.
Harold C. Simmons Comprehensive Cancer Center performs the greatest range of brachytherapy treatments on the most types of tumors of any medical center in Texas – and we are the only North Texas center to offer intraoperative radiation therapy (IORT), a technique to apply high dose radiation during tumor removal surgery.
Brachytherapy uses no external radiation beams. Instead, tiny capsules, pellets, seeds, or wires are implanted in the body to deliver radiation directly to a tumor. This technique destroys more cancer cells while minimizing damage to surrounding healthy tissues or organs.
Certain tumors require higher doses of radiation and some require longer or multiple courses of treatment. Patients who have high-dose-rate (HDR) brachytherapy receive a powerful dose of radiation in a session lasting 20 minutes or less.
HDR brachytherapy is often an outpatient procedure, but patients may need additional sessions over a few days or weeks. The radiation devices are removed before the patient leaves the hospital, so there is no risk of "being radioactive" once the patient goes home.
Low-dose-rate (LDR) brachytherapy, however, delivers radiation at a slower pace. The treatment is administered through implanted “seeds” or devices designed to stay in the body for several days; in the case of prostate brachytherapy, the seeds may be permanent, but their radiation will resolve over time (weeks to months).
In some cases, patients might stay in the hospital for a few days to receive several treatments of HDR brachytherapy, but the treatments are usually outpatient procedures and patients return home the same day. Some patients who receive LDR brachytherapy will be radioactive for a period of time and may have some restrictions around small children or pregnant women.
How we deliver brachytherapy
Brachytherapy is administered differently based on the location and severity of the cancer, and the patient's overall health and treatment goals:
- Interstitial brachytherapy: The source is placed within body tissue, such as in the prostate or breast, and may be removed after treatment (HDR, or temporary) or left in place (LDR, or permanent).
- Permanent brachytherapy: In some cases, a permanent device will be implanted that releases radioactive material over a few weeks. The radiation dose is low, and the risk of "being radioactive" and harming others is minimal. However, we may recommend limiting the amount of time you spend with pregnant women or children.
- Intracavitary brachytherapy: The radioactive source is placed in an area near the tumor, such as the cervix or rectum. The device is removed after treatment; this is almost always an HDR treatment.
Patients receive general or local anesthesia during placement of the radioactive substances. We use imaging guidance such as ultrasound, MRI, or CT scan to place the radiation device in exactly the right spot using a needle or a thin, flexible tube known as a catheter.
Brachytherapy tends to cause fewer side effects overall than more traditional external beam radiation, but often has some short-term side effects that are specific to the placement of the brachytherapy device and/or seeds. The process shouldn’t be painful, but you may feel a bit of discomfort or tenderness in the area where the radioactive device is inserted.
How IORT is performed
IORT requires specialized equipment and expertise, as well as collaboration between the cancer surgeon and the radiation doctor, because the tumor is removed during the same procedure as placement of the IORT device.
A doctor may recommend IORT for tumors that are difficult to remove or when there is a concern that cancer cells may remain after surgery.
Simmons Cancer Center is equipped with a special operating room in which we perform IORT. Once the surgeon removes the tumor, the radiation doctor places an IORT device directly into the tumor site. There, it delivers a high dose of radiation while the patient is still under anesthesia for surgery.
The elevated dose can shorten the total course of radiation in some patients, as well as reduce the risk of the tumor coming back in that site.
Breaking down the benefits of brachytherapy
Michael Folkert, M.D., Ph.D., provides a close-up look at brachytherapy, which uses delicate implements to deliver precision doses of radiation to a tumor. The list of cancers for which brachytherapy is effective is expanding and UT Southwestern is one of the leading centers in Texas for this cancer treatment.
What’s next for brachytherapy
UT Southwestern is on the leading edge of brachytherapy techniques. Our research is focused on finding better, more effective ways to treat our patients.
One area we're investigating is the use of temporary brachytherapy for liver tumors, in which one or more brachytherapy catheters are placed using CT and ultrasound guidance under anesthesia. Treatment is delivered in a single session to destroy the tumor in the liver. Brachytherapy delivers far less of a dose to the rest of the liver than traditional external beam radiation therapy and may preserve liver function better than other approaches.
Another area we are investigating is the combination of IORT with hyperthermic intraperitoneal chemotherapy (HIPEC), which involves filling the abdominal cavity with chemotherapy drugs that have been heated after a tumor has been removed. These techniques are used with very advanced cancers that have spread throughout the abdomen. We are researching how this combination therapy, which, like IORT, begins during surgery, might improve gastrointestinal cancer outcomes and are developing a clinical registry.
We are also using focal salvage high-dose-rate (HDR) brachytherapy as a treatment for prostate cancer that has come back after prior radiotherapy. Such recurring prostate cancers often are currently treated with indefinite palliative hormonal therapies, which can cause side effects such as fatigue, loss of muscle mass, and sexual dysfunction, or with salvage surgery that can result in significant incontinence. Using one or two sessions of HDR brachytherapy, we can treat the portion of the prostate where the cancer has been shown to have recurred using MRI imaging.
Traditional curative treatments can come with high toxicity rates that can damage surrounding healthy tissue. We hope that by using image-guided brachytherapy as a curative treatment, we can escalate the radiation dose to the tumor while limiting exposure to the surrounding organ.
Brachytherapy can play an important role in cancer treatment, and it should only be performed in a center with a high level of expertise. It requires a team effort to achieve the best outcomes while maintaining a patient's quality of life.
And brachytherapy is not just for the treatment of cancer; at UTSW, we are also working closely with our colleagues in interventional cardiology to offer intravascular brachytherapy during coronary angioplasty procedures to help keep the heart’s crucial blood vessels open and flowing after patients have developed blockages in their coronary stents.