The use of surface‐enhanced laser desorption/ionization time‐of‐flight mass spectrometry to detect putative breast cancer markers in saliva: a feasibility study

Abstract
Technologies are now available enabling saliva to be used to diagnose disease, predict disease progression, and monitor therapeutic efficacy. This pilot study describes the use of surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI) to detect putative breast cancer markers in saliva. Salivary specimens were analyzed as either pooled cancer saliva specimens, or individual specimens from healthy women and women diagnosed with carcinoma of the breast. The specimens were applied to a variety of protein chip arrays, washed extensively to remove unbound analytes and analyzed on a SELDI mass spectrometer. The results of this initial study suggest that the WCX protein chip array prepared and washed at pH 3.5 yielded the most promising results. Additionally, the analyses revealed a number of proteins that were higher in intensity among the cancer subjects when compared with controls. These salivary proteins were present at the 18, 113, 170, 228 and 287 km/z ranges using SELDI analyses. The study suggests that saliva may be useful for high-throughput biomarker discovery.