Patients
Patients referred for CRC surgery or for diagnostic colono- scopy in Riga East University hospital or Digestive Diseases Centre GASTRO (Riga, Latvia) were recruited to the study group. Altogether 209 subjects were recruited, 65 had CRC, and 22 were included in the adenoma group. The remaining 122 patients were in the control group (See detailed informa- tion in Table 1 and in the “results” section below). All patients provided signed consent prior to enrolment. Breath samples were collected before surgery or colonoscopy, that is, prior to the potential removal of any lesions revealed during the procedure. In the control group without removable lesions volatile marker sampling was also performed starting from 1 week after colonoscopy.