ORLANDO, FL USA (UroToday.com) - Given the significance of second harmonic generation (SHG)-based optical biomarkers in various cancers—including ovarian and breast cancer—these authors sought to examine whether this application might also be useful in renal cell carcinoma (RCC). Previous analyses have demonstrated subjective differences in intrinsic collagen signals between malignant and benign renal tissue, while improvements in digital analytic technology and software allow for quantification of SHG-based optical biomarkers, in order to develop an “SHG signature” predicting RCC prognosis and outcomes.
The authors developed a tissue microarray (TMA) using small (0.6 mm) cores of renal tissue specimens of various grades (RCCs grades 1–4, benign tissue). After preparing and staining (H&E) five μm sections of the TMA, the authors captured bright-field and SHG images. These images were then analyzed using CT-FIRE software, which sensitively characterizes changes in collagen angle, thickness, and length.
The renal tissue specimens (benign and malignant) all generated excellent SHG signals from the collagen fibers. The small samples used in the microarray are analogous in size to a renal tumor biopsy. Software analysis of the images quantified collagen fiber width, straightness, length, and fiber angle. Quantification results demonstrated significantly increased alignment of collagen fibers with higher-grade disease, while bright-field images demonstrate qualitative fiber alignment.
The authors conclude that “SHG imaging provides a flexible platform” for renal tumor analysis, and it might serve as a useful adjunct in better characterizing both whole specimens and biopsy cores. Future studies are necessary to link these collagen-based optical biomarkers with RCC patient outcomes, while other analyses are necessary to further elucidate the role of collagen in RCC progression.
Presented by Sara Best at the American Urological Association (AUA) Annual Meeting - May 16 - 21, 2014 - Orlando, Florida USA
University of Wisconsin, Madison, WI USA
Written by Eric Ballon-Landa, BA, University of California (Irvine), and medical writer for UroToday.com