m/z P Peak area Ratio1 Assignment Breast Lung 2,752 0.008 16 26 0.6 　 6,277 0.004 29 48 0.6 　 8,566 0.004 102 189 0.5 　 10,093 0.008 175 353 0.5 S100A6 Ratio1, the peak area ratio of breast to lung cancer

Table 1: Peaks differentially expressed between primary breast and lung adenocarcinomas at feature selection P<0.01.