SRC and adenocarcinoma: Fig 1 demonstrated Raman spectra of normal gastric mucosa (Fig 1a), SRC (Fig 1b), MCA (Fig 1c), TAC (Fig 1d), and PAC (Fig 1e). Raman signals at 861, 1004, 1098–1128, 1240, 1342, 1442, 1584, and 1655 cm−1 were respectively assigned to the vibrational modes of C–C stretching, C–C symmetric stretching, C–N stretching, C–N stretching and N–H bending, CH3CH2 wagging, CH2 and CH3 bending, C = C bending, and C = O stretching [43]. Significant spectral difference among the four types of adenocarcinoma and the normal one was apparent in two segments, 1098–1128 cm−1 and 1240–1342 cm−1.