Since the 1950s, researchers have been aware of the difficulty in effectively treating tumors deprived of oxygen, a problem that is further exacerbated when treating them with radiotherapy. In spite of this, patients are not routinely subjected to tests that evaluate tumor oxygen levels due to the absence of a single cost-effective, accurate, and readily available test. Now, imaging researchers have come closer to accomplishing their goal of identifying cancers that are deprived of oxygen, which would aid in tailoring effective, targeted treatments for these cancers.

A team of researchers from The University of Manchester (Manchester, UK) and The Institute of Cancer Research (ICR, London, UK) achieved this breakthrough by combining two cutting-edge technologies: an MRI scanner that also delivers radiotherapy - called MR-Linac - to measure the oxygen levels in tumors.

In a study involving 11 head and neck cancer patients, researchers successfully performed scans using the MR-Linac machine and subsequently generated maps of oxygen levels - a first in this field. It is important to note that this technology has the potential to be applicable to most types of cancer. During the process, patients inhaled room air through a mask, followed by pure oxygen to bathe the tumor with the gas. Oxygen-enhanced MRI, as the technique is called, was able to distinguish between tumor portions with different oxygen levels; areas with good oxygenation showed varied responses compared to those that were oxygen-depleted, thereby helping to identify the sections of the tumor that were starved of oxygen and may be resistant to radiotherapy.

“This imaging lets us see inside tumors and helps us understand why some people with cancer need an extra boost to get effective treatment. This is an important step towards the goal of changing treatment based on imaging biology,” said lead author Professor James O’Connor, Professor of Quantitative Biomedical Imaging at The Institute of Cancer Research.

“The MR-Linac is an exciting technology that combines highly precise imaging and radiotherapy delivery that allows for real-time imaging,” added first author Dr. Michael Dubec from The University of Manchester. “We are tremendously excited about what is the first application in humans of 'oxygen-enhanced MRI', developed as a result of a multi-disciplinary team working across the country which has exciting implications on patient outcomes.” 

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