  We present a proof of concept for screening breast cancer risk by detecting
biochemical alterations in breast tissue using a noninvasive and low-cost
technique that uses dynamic light scattering for field effect detection by
spectral analysis (FEDSA). This technique consists of a light source that
illuminates the tissue, and the backscattering light by the tissue is acquired
by two detectors; next, the signal goes to the acquisition system, and then
with the designed software the power spectra are calculated. The power spectra
contain the frequency contribution related to the size of tissue compounds.
These frequency contributions change with the biochemical alterations that are
amplified by the field effect on tissue. This implies that the initial
alterations in the breast are not local. To test FEDSA, two experiments were
performed: the first was with Alumina particles grouped in average sizes of
$60-300nm$, $100 - 400nm$ and polystyrene nanoparticles in suspension
($315nm$). The second was with 24 women, 17 of whom had normal tissue and 7
abnormal; abnormalities were previously detected by mammogram or ultrasound.
Power spectra were obtained for all particles, in agreement with the particle
size. In the case of normal and abnormal tissues, the power spectra of the
tissues show differences in the shape of the spectra in the range of 1 to 160
kHz. ROC analysis suggests a possible good sensitivity (87.5\%) and specificity
(68.1\%) in classifying breast tissue conditions. Statistical analysis with
$p<0.05$ revealed significant differences in two quadrants of the breast, the
upper inner right and the upper outer left, which were consistent with previous
diagnoses by mammography and ultrasound. This proof of concept opens the
possibility of implementing and improving FEDSA in the detection of early
anomalies in the breast as a low-cost technique that does not use ionizing
radiation.
