Raman microspectroscopy for the early detection of pre-malignant changes in cervical tissue

Cervical cancer is the third most common cancer affecting women worldwide. The mortality associated with cervical cancer can, however, be significantly reduced if the disease is detected at the pre-malignant stage. The aim of this study was to evaluate the potential of Raman microspectroscopy for elucidation of the biochemical changes associated with the pre-malignant stages of cervical cancer. Formalin fixed paraffin preserved tissue sections from cervical biopsies classified as negative for intraepithelial lesion and malignancy (NILM), low grade squamous intraepithelial lesion (LSIL) or high grade squamous intraepithelial lesion (HSIL) were analysed by Raman spectral mapping. Raman mapping, with K-means cluster analysis (KMCA), was able to differentiate the NILM cervical tissue into three layers including stroma, basal/para-basal and superficial layers, characterised by spectral features of collagen, DNA bases and glycogen respectively. In the LSIL and HSIL samples, KMCA clustered regions of the superficial layer with the basal layer. Using principal components analysis (PCA), biochemical changes associated with disease were also observed in normal areas of the abnormal samples, where morphological changes were not apparent. This study has shown that Raman microspectroscopy could be useful for the early detection of pre-malignant changes in cervical tissue.