Optical reflectance spectroscopy to differentiate benign from malignant renal tumors at surgery

Optical reflectance spectrophotometry (ORS) is part of a group of novel techniques that have demonstrated promise for the assessment and differentiation of various solid tumors. In this study, we evaluated the ability of ORS to differentiate malignant from benign kidney tumors at surgery.

From January to April 2007, we completed optical spectroscopy measurements (OSM) at several standardized tumoral and normal parenchymal locations immediately after specimen removal during radical or partial nephrectomy. The depth of tissue penetration with our specific probe was 1 mm. We compared the slopes of the optical reflectance curves between 630- and 900-nm wavelengths and assessed the correlation between benign and malignant tumors.

There were 8 partial and 13 radical nephrectomies for 6 benign (oncocytomas) and 15 malignant (14 clear cell and 1 papillary) tumors. Overall, benign and malignant OSM slopes were significantly different (P = .005). In the near-infrared region, there was excellent correlation among benign (r = .99) and malignant OSM (r = .97). On the contrary, there was a poor correlation coefficient when we compared benign and malignant tumors (r = .49).

Optical reflectance spectrophotometry may be a novel real-time method to distinguish malignant from benign tumors in vivo. However, we performed these pilot study measurements immediately after specimen removal, and therefore expansion to in situ assessments is necessary.