You might think that the US space program doesn’t have anything to do with cancer. But you’d be wrong.
Recent research from the National Space Biomedical Research Institute in Houston, Texas may shed light on a new way to reduce bone damage caused by radiotherapy.
Scientists at the Institute are working to understand exactly how space radiation affects the bones of astronauts travelling on long missions. Radiation from the sun and from outside our galaxy causes astronauts’ bones to become less dense. Unfortunately this doesn’t make floating round their spaceship any easier, and in fact it could cause dangerous fractures when they reach their destination.
Back on Earth, doctors are familiar with this problem – it can be caused by radiotherapy treatment for cancer. For example, radiotherapy targeted to the pelvis can cause bone damage, and can even increase the risk of hip fractures in some patients. According to Dr Ted Bateman, the team leader,
“We know that older women receiving radiotherapy to treat pelvic tumours are particularly vulnerable to fracture,”
Research carried out by the team has shown that radiation activates cells called osteoclasts, which break down old bone. According to their research, which was carried out in mice, even quite low doses of radiation – much lower than would be used in radiotherapy treatment – could have a damaging effect.
Although they’re trying to crack a space-age problem, the solution may prove more down-to-earth. Existing drugs called bisphosphonates can help to reduce the numbers of osteoclasts, strengthening the bone.
Bisphosphonates are already used to treat osteoporosis, as well as cancers that often spread to the bone such as breast and prostate cancer. Cancer Research UK is supporting a number of trials of these drugs, notably in prostate cancer (for example, RIB, STAMPEDE and ZICE for breast cancer).
The Texan scientists think these drugs could also be effective at preventing bone loss after radiation exposure – both in space and on earth. They’ve recently shown that a bisphosphonate called risedronate can prevent bone loss in mice treated with radiotherapy.
They’re now carrying out some small clinical trials with cancer patients to see if, at a cellular level, what they see in mice occurs in people. If it does, this could open the door to trials of bisphosphonates to help stop this process.
So, perhaps in the future bisphosphonates could have a new role as a way to reduce one of radiotherapy’s side effects. Although this work was initially meant to help intrepid space explorers it could have some welcome benefits a bit closer to home.
Willey, J. et al (2008). Early Increase in Osteoclast Number in Mice after Whole-Body Irradiation with 2 Gy X Rays Radiation Research, 170 (3), 388-392 DOI: 10.1667/RR1388.1
Willey, J.S. et al (2009). Risedronate prevents early radiation-induced osteoporosis in mice at multiple skeletal locations. Bone PMID: 19747571