title: Secondary electrospray ionization-mass spectrometry and a novel statistical bioinformatic approach identifies a cancer-related profile in exhaled breath of breast cancer patients: a pilot study.
abstract: Breath analysis represents a new frontier in medical diagnosis and a powerful tool for cancer biomarker discovery due to the recent development of analytical platforms for the detection and identification of human exhaled volatile compounds. Statistical and bioinformatic tools may represent an effective complement to the technical and instrumental enhancements needed to fully exploit clinical applications of breath analysis. Our exploratory study in a cohort of 14 breast cancer patients and 11 healthy volunteers used secondary electrospray ionization-mass spectrometry (SESI-MS) to detect a cancer-related volatile profile. SESI-MS full-scan spectra were acquired in a range of 40-350 mass-to-charge ratio (m/z), converted to matrix data and analyzed using a procedure integrating data pre-processing for quality control, and a two-step class prediction based on machine-learning techniques, including a robust feature selection, and a classifier development with internal validation. MS spectra from exhaled breath showed an individual-specific breath profile and high reciprocal homogeneity among samples, with strong agreement among technical replicates, suggesting a robust responsiveness of SESI-MS. Supervised analysis of breath data identified a support vector machine (SVM) model including 8 features corresponding to m/z 106, 126, 147, 78, 148, 52, 128, 315 and able to discriminate exhaled breath from breast cancer patients from that of healthy individuals, with sensitivity and specificity above 0.9.Our data highlight the significance of SESI-MS as an analytical technique for clinical studies of breath analysis and provide evidence that our noninvasive strategy detects volatile signatures that may support existing technologies to diagnose breast cancer.
authors.affiliation: National Research Council, Institute for Biomedical Technologies, Segrate, Milan, Italy.
authors.forename: Pablo
authors.initials: P
authors.lastname: Martinez-Lozano Sinues
authors.forename: Elena
authors.initials: E
authors.lastname: Landoni
authors.forename: Rosalba
authors.initials: R
authors.lastname: Miceli
authors.forename: Vincenza F
authors.initials: VF
authors.lastname: Dibari
authors.forename: Matteo
authors.initials: M
authors.lastname: Dugo
authors.forename: Roberto
authors.initials: R
authors.lastname: Agresti
authors.forename: Elda
authors.initials: E
authors.lastname: Tagliabue
authors.forename: Simone
authors.initials: S
authors.lastname: Cristoni
authors.forename: Rosaria
authors.initials: R
authors.lastname: Orlandi
mesh_terms: D001943:Breast Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D001944:Breath Tests / Q000379:methods; D016022:Case-Control Studies; D015331:Cohort Studies; D019295:Computational Biology; D001330:Electronic Data Processing; D045853:Exhalation; D005260:Female; D006801:Humans; D055432:Metabolomics / Q000379:methods*; D010865:Pilot Projects; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*