Affiliations: Beckman Laser Institute, University of California,
Irvine CA, USA | Laboratory for Fluorescence Dynamics, University of
California, Irvine, CA, USA | Department of Biomedical Engineering, University of
California, Irvine, CA, USA | Biophysics and Computational Biology Program,
University of Illinois, Urbana-Champaign, IL, USA | College of Medicine, University of Illinois,
Urbana-Champaign, IL, USA
Note: [] Corresponding author: Enrico Gratton, University of
California-Irvine, 3210 Natural Sciences II Building, Irvine, CA 92697-2715,
USA. Tel.: +1 949 824 2674; Fax: +1 949 824 1727; E-mail: egratton22@yahoo.com
Abstract: We have discovered quantitative optical biomarkers unique to cancer
by developing a double-differential spectroscopic analysis method for
near-infrared (NIR, 650–1000 nm) spectra acquired non-invasively from breast
tumors. These biomarkers are characterized by specific NIR absorption bands.
The double-differential method removes patient specific variations in molecular
composition which are not related to cancer, and reveals these specific cancer
biomarkers. Based on the spectral regions of absorption, we identify these
biomarkers with lipids that are present in tumors either in different abundance
than in the normal breast or new lipid components that are generated by tumor
metabolism. Furthermore, the O-H overtone regions (980–1000 nm) show distinct
variations in the tumor as compared to the normal breast. To quantify spectral
variation in the absorption bands, we constructed the Specific Tumor Component
(STC) index. In a pilot study of 12 cancer patients we found 100%
sensitivity and 100% specificity for lesion identification. The STC index,
combined with other previously described tissue optical indices, further
improves the diagnostic power of NIR for breast cancer detection.
Keywords: Breast cancer, optical spectra, Near Infrared Spectroscopy (NIRS) lipids, lipid spectroscopy
