Towards detection of positive resection margins with diffuse reflectance spectroscopy during breast conserving surgery

Abstract

In 10 to 40% of breast cancer patients treated with breast conserving surgery, ductal carcinoma in situ (DCIS) or invasive carcinoma (IC) is present at the margin of the specimen. Diffuse Reflectance Spectroscopy (DRS) could potentially help the surgeon during surgery in avoiding these tumor positive resection margins. Here we assess the feasibility of DRS for discriminating healthy breast tissue from tumor. For this purpose, DRS measurements (400-1600nm) were obtained in 71 breast specimens. A custom-made grid was placed on top of a slice of the resection specimen to accurately correlate the DRS measurements with histopathology. To assess DRS for the discrimination between healthy and tumor tissue types, a support vector machine based classification algorithm was developed. A total of 1081 locations were included, of which 236 locations were considered homogenous (> 95% fat, connective tissue, IC, or DCIS) and 845 locations consisted of a mixture of tissue types. The spectra of pure DCIS locations were similar to the spectra of pure IC, suggesting that these tissue types could not be separated based on their spectra. In a first analysis it was found that locations of pure fat, pure connective, and pure tumor tissue (both DCIS and IC) could be discriminated with accuracies of 0.95, 0.95, and 0.79 respectively. Classification of mixture locations was more challenging. The accuracy for tumor detection depends on the amount of tumor present in the measurement volume. These results indicate that DRS can potentially be used for the detection of tumor at the resection margin.