Intraoperative detection of sentinel lymph node metastases in breast carcinoma by Fourier transform infrared spectroscopy.

BACKGROUND Sentinel lymph node (SLN) biopsy is a routine surgical staging procedure in clinically lymph node-negative breast cancer. Fourier transform infrared (FTIR) spectroscopy, a technique based on the biochemical composition of the tissue, has previously been found to be capable of differentiating between normal and malignant tissue. The aim of the present study was to explore the intraoperative use of FTIR spectroscopy for rapidly identifying metastatic SLNs, and distinguishing between metastatic and non-metastatic tissue. METHODS Freshly removed SLNs from patients with breast cancer were analysed. Samples were measured by FTIR spectroscopy before histopathological diagnosis. The FTIR spectrum of each sample identified ten bands from 2000 to 900 cm(-1) . The peak position, intensity and full width at half maximum of each absorbent band were measured, and the relative intensity ratios calculated. Canonical discriminant analysis was performed to discriminate between metastatic and non-metastatic samples. RESULTS A total of 149 SLNs were removed from 49 patients. Histopathological examination confirmed 38 metastatic and 111 non-metastatic SLNs. Eighteen of 29 parameters were significantly different between the metastatic and non-metastatic SLNs. Five parameters were selected as independent factors to form discriminant functions. The sensitivity, specificity and accuracy of this method were 94·7, 90·1 and 91·3 per cent respectively. The accuracy of histological analysis of frozen sections was 100 per cent. CONCLUSION FTIR spectroscopy is a promising technique for the real-time diagnosis of SLN metastasis during breast cancer surgery. Surgical relevance Sentinel lymph node (SLN) biopsy is a highly accurate predictor of overall axillary status and has become the standard in disease staging in clinically node-negative breast cancer. A rapid and accurate intraoperative assessment of metastatic spread to the SLN provides the necessary information for the surgeon to proceed with immediate axillary dissection. The results of this research indicate that Fourier transform infrared (FTIR) spectroscopy is a rapid, accurate, non-destructive and cost-effective molecular method that can be used to detect SLN metastasis during surgery. FTIR analysis could be useful for the intraoperative diagnosis of lymph node metastases at large institutions, thereby reducing the workload of pathologists, as well as in regions lacking pathologists such as in developing countries.