A drug used to help doctors interpret medical scans may also help to boost the potency of anti-cancer therapies, research suggests.
Chemotherapy can damage healthy cells
Mangafodipir is used as a contrast agent in hi-tech magnetic resonance imaging (MRI).
French researchers found it increased the cancer-killing ability of some chemotherapy drugs, while at the same time protecting normal cells.
Details are published in the Journal of the National Cancer Institute.
Many anti-cancer drugs work by increasing the levels of hydrogen peroxide in tumour cells.
Tumour cells are particularly sensitive to the chemical, and die as a result.
However, certain enzymes in the body can work to protect cells from this kind of damage, rendering certain cancer drugs less effective.
In addition, the drugs are toxic to normal cells.
Mangafodipir was found to help promote the production of hydrogen peroxide while at the same time, through different biological mechanisms, protecting healthy cells from damage.
A team from the Groupe hospitalier Cochin-Saint Vincent de Paul in Paris carried out tests on tumour cells and white blood cells taken from cancer patients, and white blood cells taken from healthy patients.
Each type of cell was exposed to three chemotherapy drugs - paclitaxel, oxaliplatin, and 5-fluorouracil - in the presence and absence of mangafodipir.
Mangafodipir was found to protect the white blood cells taken from both the healthy volunteers and the cancer patients.
The researchers also studied the effects of mangafodipir on mice with colon cancer who were being treated with paclitaxel.
They found the drug protected the animals from infection which could compromise their immune system, and seemed to increase the cancer-killing potency of paclitaxel.
Henry Scowcroft, cancer information officer at Cancer Research UK, said: "Mangafodipir was developed in the early nineties and has a good track record in cancer diagnosis.
"We welcome the discovery that this well-understood and tolerated chemical can increase the effectiveness of conventional chemotherapy.
"These exciting preliminary results now need to be followed up in further trials, to make sure that the chemical is as safe when used for treating cancers as it is for helping detect them."