Optical spectroscopy for therapeutic guidance in breast conserving therapy

Most women with early breast cancer have the option of breast conserving therapy, which involves the complete removal of the primary breast lesion (a lumpectomy) with tumor-free margins, followed by radiotherapy. Since the presence of tumor at or near the margin is strongly correlated with the risk of local tumor recurrence, there is a need to develop a non-invasive, real-time tool that can differentiate normal breast tissue from tumor at the margins to assure complete removal. Our previous studies have demonstrated the ability of combined autofluorescence and diffuse reflectance spectroscopy to differentiate normal from non-normal breast tissue ex vivo. Using a portable, combined fluorescence and reflectance spectroscopy system, measurements were taken from each of the six surfaces of the tissue mass immediately following removal during lumpectomies for 24 patients. After correlation with histopathology, a multivariate statistical algorithm classified the 27 tumor spectra and 102 normal spectra with 78% sensitivity and 99% specificity, or 94% negative and 95% positive predictive value. Since point spectroscopy is ultimately insufficient for this application due to its small sampling area, fluorescence and reflectance spectral images from a lumpectomy specimen were gathered and used to show the feasibility of this approach.