High-grade PIN : Clinical Significance
The earliest studies on the clinical significance of high-grade PIN were carried out in the era of sextant biopsies. Given the inherent problems with sampling, small foci of cancer adjacent to high-grade PIN often remained undetected (as they were not sampled) and were subsequently discovered on repeat biopsies. The risk of detecting cancer following an initial diagnosis of high-grade PIN was cited as high as 50%; repeat biopsies were routinely recommended. In the contemporary era of extended 12-core prostate biopsies, the risk of detecting cancer on a repeat biopsy in a patient with high-grade PIN is around 20% to 25%. This is only slightly greater than the risk of finding cancer on a repeat biopsy if the initial biopsy is benign (19%).