Some researchers have produced a prototype breathalyzer that can help detect lung cancer; hopefully this will lead to earlier detection (and thus better treatment). Here’s a short article on it.

They believe the technology could lead to cheap, portable breath-test devices with the potential to save large numbers of lives by spotting cancer early.
The lung cancer biomarkers were found by comparing breath samples from 40 diagnosed patients and 56 healthy individuals.
From the results, the researchers identified 42 “volatile organic compounds” (VOCs) present in the breath of 83% of cancer patients but fewer than 83% of healthy volunteers.