ELN and neoplasm: For example, the ratio of intensities at 1655 cm−1 (C=O stretching of collagen and elastin) to 1455 cm−1 (CH2 scissoring of proteins and lipids) has been used to spectrally separate tumours from normal tissues in the brain, breast, colon cervix, and the lung (Utzinger et al, 2001; Huang et al, 2003), as both bands are sensitive to histological abnormality (Mahadevan-Jansen and Richards-Kortum, 1996).