Concentration distributions of isoprene (determined by PTR-MS) in exhaled breath of lung carcinoma patients ( CA-patients-female : red; CA-patients-male : dark red) and healthy volunteers ( control < 50 years, female : green; control < 50 years, male : dark green; control > 50 years, female : blue; control > 50 years, male : dark blue). The concentration is shown in logarithmic scaling. The median concentration of isoprene in exhaled breath of cancer patients is 81.5 ppb, whereas in healthy controls it is 105.2 ppb. For females, the median concentration for isoprene in breath is: for CA-patients 72.9 ppb; for control < 50 years 103.9 ppb and for controls > 50 years 98.1 ppb. For males, the median concentration for isoprene in breath is: for CA-patients 87.1 ppb; for control < 50 years 133.7 ppb and for controls > 50 years 100.0 ppb. Separated for gender, the difference for CA-patients and control, older 50 years was statistically significant for females: p-value < 1.0*10-5, but not for males: p-value = 0.022.