FTIR spectroscopy
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2018
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NEXT FRONTIERS TO CURE CANCER
Resumo
Biological molecular bonds with an electric dipole moment
that can change by atomic displacement due to natural vibrations
are infrared active and therefore are quantitatively
measured by Fourier transform Infrared Spectroscopy
(FTIR), which is a rapid and label-free analytical tool that
has been used to study the chemical interactions between
biomolecules. The potential of FTIR spectroscopy as a diagnostic
tool to discriminate cancerous from healthy tissue
in a non-subjective manner has been well demonstrated.
However, translation into clinical practice has been relatively
slow, mainly due to the expensive and fragile infrared
substrates required to perform the measurements. Thus,
this study aims to demonstrate the ability of FTIR microspectroscopy
to discriminate healthy skin from hyperplastic,
papilloma and squamous cell carcinoma using standard
H&E stained samples placed on glass slides.
After approval of the ethics committee for research on animals
(Comite de Etica no Uso de Animais, CEUA) of Instituto
de Pesquisas Energéticas e Nucleares (IPEN) (project no.
164/15-CEUA-IPEN/SP), cutaneous neoplastic lesions were
chemically-induced in the back of Swiss mice using a well-
-stablished two-stage carcinogenesis protocol [1]. Healthy
tissue was collected from animals non-exposed to chemicals
and different diseased stages (hyperplastic epidermis,
papillomatous lesions and squamous cell carcinoma (SCC))
were obtained by varying the exposure time of the animals
to carcinogenenic factors.Tissue sections of 5 μm thickness
were obtained from formalin-fixed paraffin-embedded
(FFPE), hematoxylin & eosin stained and placed on glass slides.
FTIR images were acquired in transmission mode over
the spectral range 3000-3800 cm-1 with a pixel size of 6.25
× 6.25 μm at a spectral resolution of 4 cm-1. Spectral data were vector normalised and subjected to smoothing using
Savitzky–Golay filtering with a polynomial of second order
in an eleven point window. Principal components analysis
(PCA) was applied and the PC scores were used as input
data for linear discriminant analysis (PC-LDA) in a binary
classification test. The groups were pairwise compared and
the method was validated by leave-one-out cross-validation
(LOOCV). All pre-processing and spectral analysis were
performed on Matlab® R2017. Considering the sensitivity as
the proportion of spectra collected from healthy tissue correctly
identified in the healthy group and specificity as the
proportion of spectra measured from neoplastic skin correctly
associated to neoplastic group, the performance of
classification obtained by PC-LDA was calculated for each
pairwise comparison: Healthy × Hyperplastic, Healthy × Papilloma,
Healthy × SCC, Hyperplastic × Papilloma, Hyperplastic
× SCC, Papilloma × SCC. Sensitivity and specificity
values over 90% were obtained for all groups compared, indicating
that the information retained by bands peaking at
3000-3700 cm-1 in the infrared spectra — associated with
the stretching vibrational modes of N-H, O-H and C-H chemical
bonds on biological tissue — can discriminate normal
and malignant tissue using H&E stained samples placed on
glass slides. Thus, FTIR spectroscopy associated to PC-LDA
as a binary classification test may be used as a complementary
tool to help physicians to detect early stages of skin
cancer, as well as to differentiate different types of cutaneous
tumors.
Como referenciar
LIMA, CASSIO; CORREA, LUCIANA; BYRNE, HUGH; ZEZELL, DENISE M. FTIR spectroscopy: a valuable tool to diagnose cutaneous tumors. In: NEXT FRONTIERS TO CURE CANCER, 10-12 de maio, 2018, São Paulo, SP. Abstract... São Paulo: A.C.Camargo Cancer Center, 2018. Disponível em: http://repositorio.ipen.br/handle/123456789/30151. Acesso em: 29 Mar 2024.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.