The spare computing power of Android devices and computers can be utilised to work out which compounds can best fight cancer cells.

The work is part of a wider citizen science project, set up by IBM.

In order to help, users need to download an app.

The World Community Grid was set up by IBM in 2004, and since then more than 700,000 volunteers have helped researchers process complex computations, including ones to better understand Ebola, Zika, tuberculosis and HIV Aids.

Initially it utilised the processing power of computers but a few years ago added an Android app to its arsenal.

Now it is working with the Smash Childhood Cancer project to help find cures for six types of childhood cancer, including brain tumours, cancer of the liver and bone cancer.

"The app only runs when you have 90% charge and it waits until you are connected to wi-fi so it does not use up data. It has been designed to stay out of the way and be non-intrusive," said Juan Hindo, program manager of IBM Corporate Citizenship.

She explained that researchers looking for the best cures for a range of childhood cancers needed to run simulation tools to predict how a compound would perform to prevent disease.

Virtual super-computer

"You need a lot of computer power to do this and researchers may only be able to access a supercomputer at certain times and, to test each one, they need to run millions of simulations," said Ms Hindo.

Conducting research on this scale in a laboratory is nearly impossible because of the amount of time and expense involved.

"When you have spare computing power the app requests one of the calculations and if the person, for instance, starts to watch a video, it will pause. When it is done, it sends it back to the community grid," she said.

Ms Hindo estimates that, on average the system performs between one to two million calculations each day.

The system has previously been used to pinpoint the compounds that cause neuroblastoma, one of the most prevalent childhood cancers - 200,000 volunteers contributed to that experiment, which helped identify several potential treatments.

"For researchers, it gives them access to a virtual super-computer which allows them to think big, and for volunteers it invites the general public to play a role in scientific discovery," said Ms Hindo.

The system is currently not available for iOS, due to developer rules that govern how apps run on the Apple platform.

It is free for scientists to use but they must make the results publicly available for other researchers to access and use.