Microvessel density is not increased in prostate cancer: digital imaging of routine sections and tissue microarrays

Angiogenesis is considered a prognostic factor and therapy target in many tumors but remains controversial in prostate cancer. This study compares the microvessel density of normal prostate and prostate cancer of different grades using an automated approach to determine its clinical utility. Neoplastic and normal prostatic tissues from 60 prostatectomies were examined by routine histological sections (group I); 136 prostatectomies were used to create tissue microarrays (group II). Microvessel density was calculated using CD31 immunostaining. Automated Cellular Image System (ChromaVision, San Juan Capistrano, CA) and Aperio automated systems were used to digitally analyze microvessel density in Groups I and II respectively. Microvessel density was not significantly increased in tumor versus normal prostate in Group I (P = .303). Both the mean vessel count and vessel area were significantly higher in normal tissue than in tumor either by Automated Cellular Image System or Aperio analysis (P < .05). Aperio analysis in group II additionally showed significantly higher values in normal tissue for vessel lumen (P < .001), whereas vessel perimeter, wall thickness, vessel compactness, and shape were not significantly different (P > .05). Aperio comparison of low- versus high-grade prostate cancer demonstrated that only mean vessel count was increased in high-grade tumors (P = .047); no other automated parameter in either group showed significant association with Gleason scores. Irrespective of methodology, microvessel density was not increased in prostate cancer compared to normal prostate. The bias of using vascular hot spots that possibly contributed to previous contradictory results has been mitigated by automated microvessel density quantitation here. Similar microvessel density of low- and high-grade tumors indicate that microvessel density is neither an important nor reliable prognostic marker for prostate cancer.