Fluorescence spectroscopy and chemometrics for classification of breast cancer samples -: a feasibility study using extended canonical variates analysis

The objective of this phase I feasibility study is to investigate whether fluorescence spectroscopy of serum samples in combination with multivariate data analysis can be used to discriminate healthy females from breast cancer patients with solitary and multiple metastases, respectively. Serum samples were obtained from 39 females: 13 healthy females (controls) and 26 clinically diagnosed patients with either solitary metastases (11 patients) or multiple metastases (15 patients). Fluorescence spectra were measured on undiluted samples and samples diluted 20 times and 500 times. Extended Canonical Variates Analysis (ECVA) was applied to develop classification models on the data. Three-group ECVA based on all spectroscopic data (5221 variables) gave five misclassifications in total, while sequential ECVA models on selected excitation wavelengths yielded two errors. The fluorescence spectroscopic results were compared with results based on the three tumor markers cancer antigen 15-3 (CA 15-3), carcinoembryonic antigen (CEA), and tissue polypeptide antigen (TPA). The lowest number of errors obtained using ECVA on the biomarkers was seven. Furthermore, fluorescence spectroscopy made it possible to discover sample subgroupings: females with solitary and multiple metastases could be divided into two subgroups according to the spectral patterns of the samples. Copyright (C) 2007 John Wiley & Sons, Ltd.