Abstract
Objective:
(1) Identify changes in volatile organic compounds (VOCs) concentration within exhaled breath observed with colorectal cancer (CRCa) relative to control groups.
(2) Validate the presence of discriminative VOCs in a prospective cohort.
(3) Identify VOC changes related to CRCa recurrence following surgical resection.
Background:
Breath VOCs have the potential to noninvasively diagnose cancer.
Methods:
Exhaled breath samples were collected using 2-L double-layered Nalophan bags, and were analyzed using selected-ion-flow-tube mass-spectrometry. Gold-standard test for comparison was endoscopy for luminal inspection and computed tomography (CT) to confirm cancer recurrence. Three studies were conducted:
(1) Profiling study: 150 patients; 50 CRCa and 100 controls;
(2) Independent diagnostic validation: 79 patients; 25 CRCa and 54 controls;
(3) Independent clinical validation with tumor recurrence: 40 patients; 19 postoperative (no recurrence), and 21 CRCa recurrences.
Results:
(1) In multivariate analysis, propanal was significantly elevated in the cancer cohort compared with control patients. Using a threshold of 28 ppbv, this gave a sensitivity of 96% and specificity of 76% for CRCa diagnosis.
(2) In a prospective cohort, using a propanal threshold of 28 ppbv, this gave a sensitivity of 83.3% and specificity of 84.7%.
(3) Following surgery, propanal reduced to levels expected in control patients, and with recurrence, levels increased significantly. Using a threshold of 28 ppbv, the sensitivity for identification of CRCa recurrence was 71.4% and specificity was 90.9%.
Conclusion:
This study suggests the association of a single breath biomarker with the primary presence and recurrence of CRCa. Further multicenter validation studies are required to validate these findings.
