Diagnosis of Limited Cancer in Prostate Biopsy

Abstract

In the last decade, there has been significant shift in the objectives of prostate cancer screening, diagnosis, and management, from diagnosing and treating all cancers to clinically significant ones. New and recently emerged tools, such as magnetic resonance imaging (MRI) and molecular and genomic tests, are potentially useful in distinguishing life-threatening from low-risk, indolent tumors. However, currently there are no tests that are 100% accurate in predicting which patients may have clinically significant disease. Prostate needle biopsy is still the gold standard to establish a cancer diagnosis, and pathologists still need to evaluate prostate biopsies with due diligence and diagnose all cancers that meet the accepted diagnostic criteria.

Diagnosis of cancer in prostate biopsy is often challenging, especially when the cancer focus is minute. There are two main issues: (1) recognition of limited cancer to avoid underdiagnosis (false-negative) and (2) recognition of benign mimics of prostate cancer to avoid overdiagnosis (false-positive). Diagnosis of cancer in prostate needle biopsy requires a methodical approach using a constellation of architectural and cytological features of cancer glands and sometimes also requires ancillary immunohistochemistry. However, no two pathologists have the same threshold for diagnosing limited cancer in biopsy, and even one’s own threshold changes with time and experience. It is therefore expected that pathologists may not always agree upon a diagnosis in some borderline cases. It is critical, however, to recognize these cases as being atypical and suspicious for cancer so that further workup will ensue. In this sense, the most critical issue in prostate biopsy interpretation is to identify prostate glands that are morphologically atypical and suspicious for cancer.