Table 3. Summary of previous reports by other investigators of breath biomarkers of breast cancer.

Author #1	Assay method	Outcome
Hietanen [15]	GC	Increased pentane in breast cancer
Mangler [14]	GC MS	Specific pattern of 5 VOCs in breast cancer: 3-methylhexane, decene, caryophyllene, naphthalene, and trichloroethylene
Patterson [16]	GC MS	Clustering patterns in 383 VOCs classified breast cancer with 77% accuracy; 72% sensitivity, 64% specificity
Peng [20]	Nanosensor array And GC MS	Differentiated between ‘healthy’ and ‘cancerous’ breath and different cancer types
Stolarek [17]	Fluorimetry	Increased H2O2 level in exhaled breath condensate in breast cancer
McCulloch [22]	Sniffing dogs	Detected breast cancer with sensitivity 88% and specificity 98%
Shuster [18]	Nanosensor array	Statistically significant differences between benign and malignant breast conditions
Xu [21]	Nanosensor array	Detected breast cancer with four VOCs: heptanal, acetophenone, isopropyl myristate and 2-propanol.

Where assay techniques were employed that separated VOCs with gas chromatography (GC) and identified them with mass spectrometry (MS), a number of breath VOC biomarkers were consistent with products of oxidative stress e.g. pentane, hydrogen peroxide, and alkane derivatives including heptanal and propanol.