Raman spectroscopy studies for diagnosis of cancers in human uterine cervix

Abstract

Cancer of uterine cervix is one of the leading cancers among women in both developed and developing countries. Optical spectroscopy methods mostly Fourier transform infrared (FTIR) and fluorescence have widely been used to diagnose cervix cancer using cells as well as tissues. Raman spectra of normal and malignant tissues were recorded in fingerprint region. Normal cervix tissues are characterized by strong, broad amide I, broader amide III and strong peaks at 853 and 938 cm^-1 which can be attributed to structural proteins such as collagen. Prominent features of malignant tissue spectra with respect to normal tissue are-relatively weaker and sharper amide I, minor red shift in ΔCH₂ and sharper amide III which indicate the presence of Deoxyribonucleic acid (DNA), lipids and non-collagenous proteins. In order to develop highly objective discrimination methods, very elaborate data analysis was carried out using Principal Components Analysis (PCA). Standard sets for normal and malignant were prepared and tested retrospectively and prospectively. Several parameters such as (scores of factor, Mahalanobis distance and spectral residuals) were explored for discrimination and very clean clustering of normal and malignant spectra was achieved. A multiparametric approach (limit test) combining all the above discrimination parameters was also considered, in order to develop unambiguous discrimination. This analysis has produced very high, 99.5%, sensitivity and specificity. Results obtained in this study thus validate Raman spectroscopy methods for discrimination of normal and malignant tissues in cervical cancers.