Optical spectroscopy has been considered a promising method for cancer detection for past thirty years because of its
advantages over the conventional diagnostic methods of no tissue removal, minimal invasiveness, rapid diagnoses, less
time consumption and reproducibility since the first use in 1984. It offers a new armamentarium. Human tissue is
mainly composed of extracellular matrix of collagen fiber, proteins, fat, water, and epithelial cells with key molecules in
different structures. Tissues contain a number of key fingerprint native endogenous fluorophore molecules, such as
tryptophan, collagen, elastin, reduced nicotinamide adenine dinucleotide (NADH), flavin adenine dinucleotide (FAD)
and porphyrins. It is well known that abnormalities in metabolic activity precede the onset of a lot of main diseases:
carcinoma, diabetes mellitus, atherosclerosis, Alzheimer, and Parkinson's disease, etc. Optical spectroscopy may help in
detecting various disorders. Conceivably the biochemical or morphologic changes that cause the spectra variations
would appear earlier than the histological aberration. Therefore, “optical biopsy” holds a great promise as clinical tool
for diagnosing early stage of carcinomas and other deceases by combining with available photonic technology (e.g.
optical fibers, photon detectors, spectrographs spectroscopic ratiometer, fiber-optic endomicroscope and
nasopharyngoscope) for in vivo use. This paper focuses on various methods available to detect spectroscopic changes in
tissues, for example to distinguish cancerous prostate tissues and/or cells from normal prostate tissues and/or cells. The
methods to be described are fluorescence, stokes shift, scattering, Raman, and time-resolved spectroscopy will be
reviewed. The underlying physical and biological basis for these optical approaches will be discussed with examples.
The idea is to present some of the salient works to show the usefulness and methods of Optical Biopsy for cancer
detection and show new directions.