  FT-Raman spectroscopy was employed to study (in-vitro) non-altered human
colorectal tissues aiming evaluate their spectral differences. The samples were
collected from 39 patients, adding 144 spectra. The results enable one
estabilish 3 well defined spectroscopic groups of what was consistently checked
by statistical (clustering) and biological (histopathology) analysis. The
similarity within each group was better than 90%. Groups 1 and 2 had 80% of
similarity while presenting both 70% of similarity to group 3. All groups
presented connective and epithelial tissues as histopathological
characteristic. Group 1 differs from others by the presence of soft muscle
while group 3 by presence of fatty tissue. Tissues from group 2 are composed by
samples with connective and epithelial tissues. This study is very relevant in
order to establish the non-altered or normal spectroscopic standard for future
studies and applications on optical biopsy and diagnosis of colorectal cancer.
