Vibrational Spectroscopy and Cancer - Vibrational Spectroscopy for Tissue Analysis - page 65

The possibility of molecular-level cancer diagnosis of human lung tissues
using near-infrared Raman spectroscopy was investigated by S. Kaminaka
et al. They used an Nd:YAG laser of 1064 nm and could collect totally
fluorescence-free Raman spectra of normal and cancerous lung tissues. It
was concluded that the technique probed lung cancer unambiguously at the
molecular level and could be used as a tool for cancer diagnosis [69].
Z. Huang et al. reported on diagnosis of lung cancer using near-infrared
Raman spectroscopy. The objective of their study was to explore the tech-
nique for distinguishing tumour from normal bronchial tissue. A rapid-
acquisition dispersive-type NIR Raman spectroscopy system was used
for tissue Raman studies at 785 nm. Raman spectra differed significantly
between normal and malignant tumour tissues, namely, squamous cell car-
cinoma (SCC) and adenocarcinoma. Tumours showed higher-percentage sig-
nals for nucleic acids, tryptophan, and phenylalanine and lower-percentage
signals for phospholipids, proline, and valine, in comparison with normal
tissues. Raman spectral shape differences between normal and tumour tis-
sues were also observed particularly in the regions of 1000-1100, 1200-1400,
and 1500-1700 cm −1 , which contain signals related to CH stretching modes
of protein, lipid, and nucleic acid conformations. The ratio of Raman intensi-
ties at 1445 to 1655 cm −1 provided good differentiation between normal and
malignant bronchial tissue ( p < 0.0001). The results of this exploratory study
indicated that NIR Raman spectroscopy provides significant potential for
noninvasive diagnosis of lung cancer in vivo based on the optic evaluation
of biomolecules [70].
R. R. Alfano et al., using fluorescence spectra, could distinguish normal
and cancerous tissues of human lung and breast tissues. An argon ion laser
beam at 488 and 457.9 nm was focused on the front surface of the tissue to a
spot size of 200 μm and the spectra collected from different sample groups
were dissimilar [71].
Huang et al. employed near-infrared Raman spectroscopy to study the
effect of formalin fixation of normal and cancerous human bronchial tis-
sues. The aim of the study was to find out whether the variations of the
Raman spectra caused by formalin fixation would affect the potential diag-
nostic ability for the lung cancer detection. A rapid dispersive type of NIR
Raman system with an excitation wavelength of 785 nm was used. Bronchial
tissue samples were obtained from six patients with known or suspected
malignancies of the lung. Raman spectra of fresh normal and tumour tissue
were compared with spectra of formalin-fixed normal and tumour tissue.
Changes of the ratios of Raman intensities at 1445 to 1655 cm −1 and 1302 to
1265 cm −1 versus formalin fixing times varying from 2 to 24 hours were also
examined. The major Raman spectral peaks were found at 1265, 1302, 1445,
and 1655 cm −1 in both fresh and fixed bronchial tissues. However, bron-
chial tissues preserved in formalin showed a progressive decrease in over-
all intensities of these Raman peaks. The results showed that NIR Raman
spectra of human bronchial tissues were significantly affected by formalin