July 21: For radiation oncologists and their patients, small margins can make a big difference.
The University of New Mexico Comprehensive Cancer Center is among approximately 100 treatment facilities worldwide – and the only one in New Mexico – to offer an MRI-linear accelerator (MRI-LINAC).
The machine allows better precision during radiation therapy by narrowing the focus on the radiation beams and is a key component to the UNM Comprehensive Cancer Center’s recent expansion. The technology is transforming how radiation oncologists deliver radiation therapy.
Narrowing focus, even by a few millimeters, can reduce damage to surrounding tissues and organs.
Along with improved precision, MRI-LINAC also allows radiation oncologists to adjust treatment plans in real time and potentially reduce the need for multiple appointments and CT scans.
David Lee, MD, PhD, medical director of Radiation Oncology at the UNM Comprehensive Cancer Center, said the machine was installed in April and has since treated 10 cancer patients; six with prostate cancer, three with pancreatic cancer, one with rectal cancer. Several more patients are already on the schedule for treatment in the near future.
MRI-LINAC is particularly useful for prostate cancer. It may also be used to treat cancers of the pancreas, liver and kidney, as well as limited metastatic disease. These cancers are often located near other organs and soft tissue, where minimizing radiation exposure to healthy structures is critical, Lee said.
With conventional treatment, patients typically undergo CT scans one to two weeks before radiation therapy. Radiation oncologists then use those images to plan treatment on a separate system. If changes occur between the initial scan and the scheduled treatment, Lee said a new CT scan may be required, potentially delaying care.
But because MRI-LINAC incorporates MRI technology, clinicians can image the tumor on the day of treatment and adjust the plan as needed.
“It allows us to see more clearly,” Lee said. “It allows us to be much more precise and develop personalized therapy for our patients.”
Conditions within the body can also change during treatment. In prostate cancer, for example, changes in the bladder or bowel can shift the tumor’s position. Traditionally, radiation oncologists account for this by treating a wider area around the tumor, which can expose more healthy tissue to radiation.
With MRI-LINAC, Lee said clinicians can monitor tumor movement during treatment. If the tumor moves outside the targeted area, the radiation beam automatically shuts off. Once the tumor returns to the correct position, treatment resumes.
MRI-LINAC sessions take slightly longer than traditional radiation appointments but offer increased precision and flexibility. The technology can also be used at various points in a patient’s treatment plan.
For many early-stage prostate cancers, radiation therapy is an effective primary treatment option. Some patients may also receive chemotherapy or surgery in combination with radiation. Treatment decisions are made collaboratively between patients and multidisciplinary teams at the UNM Comprehensive Cancer Center. For example, Lee said one of his patients with pancreatic cancer is receiving chemotherapy and immunotherapy, with MRI-LINAC therapy integrated between systemic treatments.
“The MRI-LINAC is a powerful armamentarium against cancer,” Lee said. “It will allow us to deliver personalized, precision medicine and provide world-class care for our patients.”