Injecting a newly developed formulation of radioactive bone cement into bone could provide support and local irradiation for tumours, according to a study led by University of California, Irvine researchers.
The study shows that the new brachytherapy cement can be placed into spinal bones to directly irradiate tumours without harming the spinal cord, and the radioactive material will stay localized in the bones, which promises to virtually eliminate side effects hence offering a safer alternative to conventional radiation therapy.
The lead researchers Dr Joyce Keyak, UCI professor of radiological sciences, presented the results at the 2021 annual meeting of the Orthopaedic Research Society.
Cancers that begin in the breast, prostate, lung, thyroid, kidney and other locations can spread to and erode bones, most commonly in the spine. Further complicating matters, normal radiation treatments for this problem can threaten the spinal cord and weaken the bones already compromised by the tumour’s erosion, increasing the risk of fracture.
Currently, multiple sessions of external beam radiation are used to treat cancer that has spread to the spine. This radiation causes unpleasant side effects including nausea, vomiting and diarrhea and passes through the spinal cord, which often delays and limits treatment.
“Brachytherapy cement could be used without delay in a convenient, one-step, minimally invasive treatment to irradiate tumours,” Keyak said,“ and would not irradiate the spdinal cord or limit future treatment options.”
Through animal and computational studies, the researchers evaluated the short-term safety of injecting brachytherapy cement into vertebrae. The team tested the possible migration of radioactivity into blood, urine or faeces, the dose rate outside the injection site and the radiation dose from phosphorus-32 emissions to the spinal cord and soft tissue.
At 17 weeks post-injection, the study found that physical examinations were all normal and no activity was detected in blood, urine or faeces. The researchers found no evidence of the P-32 isotope in the circulating blood, no changes in blood work related to radioactivity and no neurological deficits.
“This localised treatment for bone tumours stays localised, and we did not see any effects outside the bone,” Keyak said. “This is important because traditional radiation therapy causes adverse effects such as nausea, vomiting and diarrhoea.”
The brachytherapy cement was developed by Dr Keyak and Dr. Harry Skinner, an orthopedic surgeon with St. Jude Heritage Medical Group by infusing a common product of their trade, bone cement, with radioactive material already used in other treatments.
The brachytherapy bone cement does not have the same side effects as traditional radiation therapy, Keyak noted, because the injection directly targets the tumour and radiation doesn’t pass through other organs, such as the intestines or stomach. Previous studies also revealed that it can immediately reduce pain in the spine, potentially getting patients off strong painkillers that could carry additional side effects.
Normally, a bone cancer patient needs 10 or more sessions of radiation therapy. But with the brachytherapy bone cement, Keyak said, a single injection can provide an equivalent, targeted tumour treatment with significantly less threat to the spinal cord and nerves.
The procedure when done while tumours are smaller could prevent further bone and spinal cord damage, while limiting the pain and side effects that patients often feel, added Dr Keyak.
The team have started a company, Bone-Rad Therapeutics, for their product and have licensed its intellectual property. The next step will be more animal studies, followed by an application for a clinical trial, they added.