Lactate in exhaled breath condensate and its correlation to cancer: Challenges, promises and a call for data.

Owing to its connection to cancer metabolism, lactate is a compound that has been a focus of interest in field of cancer biochemistry for more than a century. Exhaled breath volatile organic compounds and condensate analyses can identify and monitor volatile and non-volatile organic compounds, respectively, present in exhaled breath to gain information about the health state of an individual. Whilst the use of exhaled breath condensate for the detection of lactate in exhaled breath is a promising tool that could be used to monitor and screen for cancer, the reliability and sensitivity of detection are uncertain, and hence its value in clinical practice is limited. Currently, lactate present in plasma and exhaled breath condensate can only be used as a biomarker for advanced cancer, and therefore it presently has limited differential diagnostic importance and is rather of prognostic value.