Why MRI-guided radiation therapy is “a paradigm shift”

Jennifer Lubell , Contributing News Writer

Magnetic resonance imaging (MRI)–guided radiation therapy has generated excitement for pancreatic cancer and radiation oncology communities for its ability to significantly prolong survival compared to standard options.

The use of an MRI serves a two-fold purpose: The ability to deliver clearer pictures while ensuring that the radiation dose targets the correct area of the body.

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During an “OncLive On AirPodcast” episode, Michael D. Chuong, MD, discussed the evolution of MRI-guided radiation in cancer treatment, highlighting the MRIdian SMART system and its role in a Phase 2 cancer trial. Dr. Chuong is the vice chair and medical director of radiation oncology and leader of the gastrointestinal radiation service at Miami Cancer Institute, part of Baptist Health South Florida, located in Miami, Florida.

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MRIdian offers convenience to patients, lowers overall costs for healthcare systems, “and can result in exciting outcomes in terms of tumor control eradication as well as being able to be delivered very safely,” Dr. Chuong summarized.

MRI-guided radiation “represents a paradigm shift in how radiation therapy is delivered,” said Dr. Chuong.

Standard radiation therapy that isn’t MRI guided has its limitations. For example, searching for tumors in the upper abdomen for pancreatic cancers is very difficult to clearly see with either CT scans or X-rays, he explained.

Comparatively, MRI guidance offers significantly improved soft tissue imaging of the upper and lower abdomen and pelvis. It also offers the ability to adapt or modify the treatment—to personalize a daily radiation dose based on the anatomy the physician sees.

Through an “ablative” or very high, radiation dose, MRI enhances the ability to control or even eradicate tumors.

Miami Cancer Institute and others worldwide have been using this technology to give hope to patients who do not have surgical alternatives because their tumors are too large or extensive for surgery, said Dr. Chuong.

Over nearly six years, Dr. Chuong has been helming the institute’s MRIdian program. The program uses a noninvasive MRI technology that facilitates higher dose radiation delivery within a shorter period,

Miami Cancer Institute was one of the very first adopters of this technology in the U.S. and worldwide.

“The ability of the MRIdian device is really profound in that a substantially higher dose than what is otherwise standard of care can be safely delivered in a much more compact period of time, as short as five days or as even as short as one day,” Dr. Chuong said.

At Miami Cancer Institute, patients have received just one 30-minute treatment of high dose ablative radiation that can potentially eradicate tumors entirely, as opposed to getting treatment for weeks or months, he added.

Dr. Chuong co-led an international multicenter Phase 2 trial, the five-fraction stereotactic magnetic resonance–guided on-table adaptive radiation therapy (SMART) trial, which tested the use of MRIdian in 136 patients with borderline resectable or locally advanced pancreatic cancer.

Median survival for patients with this disease, either with chemotherapy alone or chemotherapy plus standard lower dose nonablative radiation, is only about 15 months. Two-year survival numbers are around 20%.

The high-dose escalated ablative radiation approach with MRIdian yielded higher survival rates: A two-year overall survival from diagnosis and SMART of 53.6 % and 40.5%, respectively, and minimal complications occurring three months after the end of treatment.

“This is obviously very exciting for a disease that's as difficult to treat as pancreas cancer, and … really exemplifies and highlights the ability of a technology like this to deliver such a high radiation dose that really no other type of radiation platform can deliver, at least safely,” said Dr. Chuong.

Follow up, supported by the SMART trial findings, studies are in development to further explore the benefits of MRI-guided radiation therapy for advanced pancreatic cancer, among other cancers that are difficult to treat.