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You may be familiar with the handy ‘Find My iPhone’ feature that comes with Apple cell phones. This feature uses radio waves from cell towers to direct you precisely to the spot where you dropped your device. Following similar principles, physicians can use imaging techniques to obtain signals from cancerous cells reporting their location in the body. Now, researchers are working to create an automated system that can precisely and rapidly fire back at these signals to more effectively treat small, scattered bits of tumors called metastases.
Biology guided radiotherapy (BgRT) integrates imaging technology and automated radiation administration into one system. First, cancerous cells rapidly consume a radioactive tracer compound, break it down, and produce emissions that indicate their location. The system continuously detects and analyzes these emissions, then rapidly responds by sending a beam of radiation directly to the tumor cells. While traditional radiotherapy can target 1-3 locations at once, BgRT is capable of treating up to 10.
BgRT is much faster than the traditional method of taking a full image, analyzing the result, programming the radiation dosing and finally administering. Breathing, heartbeat and muscle contractions all contribute to the movement of tumors inside the body. In the nearly one hour that it takes to complete a standard full image alone, tumor locations can change. If you had left your cell phone in a taxi, Find My iPhone data from an hour ago is not going to be very helpful. As a result, the size of the treatment target volume needs to be extended to account for this uncertainty. This means surrounding healthy tissues, not just cancerous cells, are dosed. Any radiation that a patient receives contributes to his or her overall toxicity threshold, so the radiation administered to healthy tissue decreases the amount of radiation left to treat other tumor locations. Further, traditional radiation therapy damages these healthy tissues and leads to a multitude of side effects including fatigue, memory loss, and nausea. Some of these side effects can even appear more than a year after treatment. The combination of imaging technology and radiation administration in BgRT holds a key advantage in reducing target area volume. A 2019 study reported that BgRT reduced target volume by nearly 22%.
Furthermore, 90% of patients with metastatic cancer in the U.S. are ineligible for radiotherapy in the first place due to current technological limitations. However, the ability of BgRT to treat moving tumors and minimize toxicity means that physicians could add radiotherapy to their arsenal in treating these nearly 300,000 patients per year. This is especially important when we consider studies that suggest adding radiotherapy to the current treatment regimen can improve outcomes for patients with metastatic disease. One such study reported a nearly 17% increase in three-year survival for breast cancer patients.
The complexity and challenges associated with cancer therapeutics have elucidated that synergy between different disciplines will be requisite in significantly improving patient care. BgRT was invented by two computer and electrical engineers who met in high school. They now hold roles leading the associated company RefleXion. RefleXion opened a large manufacturing space last May where work is ongoing to develop and test this technology. Biology guided radiotherapy holds the potential to treat more metastases at once, add radiotherapy to the treatment options for a large portion of patients with metastatic disease, and reduce side effects incurred by radiotherapy.
Edited by Gabrielle Dardis
Images created with Biorender
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