Vibrational Spectroscopy and Cancer - Vibrational Spectroscopy for Tissue Analysis - page 71

Analysis of band intensities in the regions of 1220-1360, 900-990, and
830-900 cm −1 allowed for a complete separation between BCC and normal
skin spectra. In conclusion, Raman spectra of BCC differed considerably from
those of normal skin and the technique can be viewed as a promising tool for
the diagnosis of skin cancer [88].
Approximately similar results have been reported by M. Panjehpour and
colleagues on in vivo diagnosis of nonmelanoma skin cancers, using laser-
induced fluorescence. A nitrogen/dye laser of 410 nm was used and samples
of normal, BCC, SCC, precancerous, and benign tissues could have been clas-
sified with an accuracy of even 100% [89].
Wong et al. applied infrared spectroscopy combined with high pressure
(pressure-tuning infrared spectroscopy) for studying the paired sections of
BCCs and normal skin from ten patients. In this study, atmospheric pressure
IR spectra from BCC were dramatically different from those from the corre-
sponding normal skin. Compared to their normal controls, BCCs displayed
increased hydrogen bonding of the phosphodiester group of nucleic acids,
decreased hydrogen bonding of the C-OH groups of proteins, increased
intensity of the band at 972 cm −1 , a decreased intensity ratio between the
CH 3 stretching and CH 2 stretching bands, and accumulation of unidentified
carbohydrates [90].
Lucassen et al. used attenuated total reflectance Fourier transform infrared
(ATR-FTIR) spectroscopy to measure hydration of the stratum corneum. It was
believed that determination of the hydration state of the skin is necessary to
obtain basic knowledge about the penetration and loss of water in the skin
stratum corneum. In this study, direct band fitting of the water bending,
combination, and OH stretch bands over the 4000-650 cm -1 wavenumber
range were applied. Separate band fits of water, normal stratum corneum,
and occluded hydrated stratum corneum spectra were obtained yielding
band parameters of the individual water contributions in the bending mode
at 1640 cm -1 , the combination band at 2125 cm -1 , and the OH stretches in the
hydrated skin stratum corneum spectra. They concluded that band fit analy-
sis of hydrated skin stratum corneum ATR-FTIR spectra offers the possibility
for quantitative determination of individual water band parameters [91].
McIntosh et al. used infrared spectroscopy to examine basal cell carcinoma
to explore distinctive characteristics of BCC versus normal skin samples
and other skin neoplasms. Spectra of epidermis, tumour, follicle sheath, and
dermis were acquired from unstained frozen sections, and analyzed quali-
tatively by t-tests and by linear discriminant analyses. Dermal spectra were
significantly different from the other skin components mainly due to absorp-
tions from collagen in dermis. Spectra of normal epidermis and basal cell car-
cinoma were significantly different by virtue of subtle differences in protein
structure and nucleic acid content. Linear discriminant analysis characterised
spectra as arising from basal cell carcinoma, epidermis, or follicle sheath with
98.7% accuracy. Use of linear discriminant analysis accurately classified spec-
tra as arising from epidermis overlying basal cell carcinoma versus epidermis