Now, an 18-year-old woman from India has developed a system for detecting oral cancer that can be used at home.
The system comprises a small heating device and a test kit that costs approximately 50 cents.
1 ml of saliva is mixed with a solution, then heated using the device.
Biomarkers of oral cancer react with the reagent, which grows darker in colour depending on the number of indicators present.
A colour scale makes a diagnosis possible. Allowing chronic smokers to seek treatment in good time.
A French app, meanwhile, can help give up smoking altogether.