Optical transillumination spectroscopy of breast tissue for cancer risk assessment

Determining an individual’s cancer risk is an important step to increase the efficacy of screening procedures. Currently, breast cancer risk can be clinically assessed using tissue density patterns seen on standard x-ray mammography. These patterns reflect the ratio of glandular tissue to adipose tissue within the breast. Increased dense areas of glandular tissue indicate a higher risk category with an odds ratio of approximately 6. Near-infrared optical transillumination spectroscopy has been shown helpful in investigating physiological and anatomical properties of the breast tissue. Similarly the adipose and glandular tissue ratio responsible for the x-ray density pattern together with other optically active tissue chromophores can result in unique optical transillumination spectra. In this study we are considering patients who had standard mammograms and examine their breast tissue by optical transillumination spectroscopy in order to establish a correlation between the two techniques and therefore the ability of using transillumination for risk estimation. The transillumination spectra show haemoglobin, water and lipid absorption characteristics. Correlation between optical transillumination spectroscopy and mammographic density pattern are established through the use of Principal Component Analysis and Linear Discriminant Analysis. Preliminary, results indicate that x-ray dense tissue can be identified with a specificity and sensitivity above 0.87 each, for both post and pre-menopausal women.