Adaptive Radiotherapy: Cancer Treatment May Be Safer, More Accessible
Adaptive radiotherapy is a form of radiation therapy that takes the pinpoint targeting of radiation to a new level of personalization for patients. Like regular radiation therapy, adaptive radiotherapy utilizes a focused plan and delivery of radiation to treat a tumor in a patient, while trying to limit the amount of surrounding healthy tissue affected by radiation.
However, adaptive radiotherapy takes this further by reassessing the status of the targeted tumor on a daily basis and adjusting the delivery of treatment to maximize effectiveness.
According to Yves Archambault, strategic initiative director at Varian, the idea driving adaptive radiotherapy is that the surrounding healthy tissue acts as a limiting factor for how aggressive radiation therapy can be without damaging the rest of the body. By regularly reassessing and adjusting, it’s possible to reduce this limitation of cancer treatment. The hope is that patient outcomes will improve for more difficult cancers including pancreatic cancer, which currently has some of the lowest survival rates.
Treatment Limitations
Treatment is similar to regular radiation therapy with patients coming into the clinic two to three times a week for radiation doses for several weeks. Adaptive radiotherapy utilizes extensive imaging to visualize every aspect of the tumor and surrounding tissue, requiring patients to lay down in a confined space for long periods of time while the equipment does its job. Patients who have trouble staying in claustrophobic spaces for long periods of time will find treatment days difficult.
Major challenges remain for more widespread implementation of adaptive radiotherapy. The imaging technology used to visualize the tumors, magnetic resonance imaging (MRI), is costly, complex, and requires extensive facilities to house the machinery. Due to the nature of magnetics, patients cannot have any metal on their person. Even those with metal alloy implants may be prohibited from undergoing this type of therapy as only specific kinds of metal alloy implants are acceptable in the MRI room. The MRI machine is also responsible for the claustrophobic space patients have to lie in while they are imaged.
For now, adaptive radiotherapy is limited to a few locations around the United States, and with high costs and long treatment days, many patients don’t have access to this treatment or might be deterred by the process.
New Imaging Methods
In the future, clinicians using adaptive radiotherapy want to move away from relying on MRI to provide imaging for treatment. With improvements on imaging interpretation and the treatment devices themselves, companies like Varian hope to switch to computed tomography (CT) for imaging in treatment devices. CT scans are almost universally available, cost much cheaper to operate and maintain, and require far fewer restrictions than MRIs.
For instance, facility requirements and disallowance of metal implants aren’t as strict for CT scans as they are for MRIs because CT scans use x-rays instead of magnetic fields to develop detailed images of the body. While CT scans also require a patient to lie still as the machine scans them, the time spent in imaging is much shorter, lasting anywhere from seconds to a few minutes.
In contrast, MRIs sometimes take longer than an hour to complete a scan. With shorter imaging times, cancer treatment centers would be able to see more patients on a daily basis and reduce backlogs.
Using alternative imaging methods will also expand the functionality of treatment machines by taking away concerns over disruptive magnetic fields. More cancer treatment centers would be able to utilize adaptive radiotherapy, increasing availability to patient populations, improving the daily strain of cancer treatments, and reducing costs for patients already burdened with high medical expenses.
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For patients facing the daunting gauntlet of cancer treatment, adaptive radiotherapy gives increased hope for tumor control and longer life expectancy for many kinds of cancers. Adaptive radiotherapy adds more personalization to treatment plans and shows promise for difficult cancers or advanced stage cancers that cannot normally be operated on.
With further improvements and expansion of access, adaptive radiotherapy will be a tremendous development for radiation therapy for many cancer patients across the United States.
Ben Duong
Benjamin Duong is a first-year medical student and freelance writer based in Dothan, Alabama. He has a Masters of Public Health from the George Washington University and majored in microbiology and political science at the University of Florida. He has worked on advocacy for issues ranging from medical education to global maternal and infant mortality.
Originally published at https://medtruth.com on August 21, 2019.
