Radiotherapy could be bolstered by a 150-year-old drug, according to scientific experiments.
Scientists believe papaverine could make the common cancer treatment more effective by controlling how much energy cells need, the Daily Mail reports.
Currently, radiotherapy is hampered when human tissue suffer hypoxia - or oxygen deficiency, which is common in malignant growths.
Their aggressive nature typically demands more oxygen than available from blood. As a result, tissue starves and radiation struggles to reach it properly.
But, now, experts say this can be managed by essentially controlling tumor appetite and oxygenation - keeping it healthy enough to absorb the ionizing rays.
Dr Nicholas Denko, a researcher in tumour microenvironments and metabolism at Ohio State University, made the discovery.
His research found that papaverine - used to treat spasms involving the intestines, heart or brain - inhibits a key element of cell DNA within cancerous growths.
It blocked the respiration of mitochondria - which creates the energy in cells that allows them to spread. As a result, by regulating oxygen supply and demand, papaverine reduces hypoxia and allows the radiation to access hard-to-reach areas.
"We know that hypoxia limits the effectiveness of radiation therapy," Dr Denko said of his study, published in the Proceedings of the National Academy of Sciences.
"And that's a serious clinical problem because more than half of all people with cancer receive radiation therapy at some point in their care. We found one dose of papaverine prior to radiation therapy reduces mitochondrial respiration, alleviates hypoxia, and greatly enhances the responses of model tumours to radiation.
"It's critical that we find ways to overcome this form of treatment resistance."
Interestingly, papaverine - first discovered in 1848 by George Merck - doesn't affect fully-oxygenated cells, meaning it only targets those that are unhealthy.
The breakthrough, touted as a 'landmark' discovery by medical experts, could potentially pave the way for a new, clinically-approved drug which would amp-up the battle against cancer.