HOUSTONA new automated computerized system for analyzing the
microvessel density of prostate tumors may help physicians more
accurately stage the cancer before surgery, and thus assist
physicians and patients in making treatment decisions, say Brian J.
Miles, MD, of Baylor College of Medicine, and his colleagues at the
Mayo Clinic, Washington University, Laval University, Quebec,
University of Colorado, and Fred Hutchinson Cancer Research Center.
The technology, optimized microvessel density (OMVD) analysis, uses
digital images of needle biopsy slides to measure the quantity of
vessels feeding the tumor.
"Microvessel density is higher in cancer tissue from patients
with extraprostatic extension than in those without extension beyond
the prostate, and appears to be a significant predictor of final
pathologic stage," says Dr. Miles, associate professor of urology.
An interim analysis of an ongoing US-Canadian multisite study showed
that the technique, when combined with PSA results and Gleason score,
significantly increased the ability to predict extrapros-tatic
extension of the tumor preoperatively (Urology 48:47-57, 1996).
The study involved 186 previously untreated patients with clinically
localized prostate cancer who underwent bilateral pelvic
lymphadenectomy and radical prostatectomy. No patient had clinical
evidence of extraprostatic extension or metastases prior to surgery.
The researchers retrospectively evaluated each needle biopsy sample
showing cancer, to determine OMVD and Gleason score; serum PSA levels
were determined preoperatively. Tumors were pathologically staged
from the prostatectomy samples (62% organ-confined cancer and 38%
with extraprostatic extension).
For each cancer field in the needle biopsy slides, the researchers
obtained a vessel image, digitally enhanced to exaggerate the
contrast between microvessels and tissue, and a tissue image,
digitally enhanced to exaggerate the contrast between tissue and
lumen space. The summed microvessel count (top figure)
and total tissue area (bottom figure)
for all fields in all biopsy cores of each specimen were combined to
The microvessel density results, Gleason scores, and PSA levels were
all significant and independent predictors of extraprostatic
extension, whereas patient age and clinical stage were not
significant. When microvessel density was combined with Gleason score
and PSA, the effect was additive, with significantly improved
To allow more accurate therapeutic stratification of patients with
prostate cancer, the researchers developed a table showing the
probability of extraprostatic extension based on Gleason score (4 to
10), PSA (2 to 50 ng/mL), and OMVD (25 to 750).
For example, according to the table, a patient with a biopsy Gleason
score of 7 and serum PSA of 8 has a 53% chance of extraprostatic
extension; the addition of OMVD alters this risk--lowering it to 37%
when OMVD is very low (25) and increasing it to 89% when OMVD is very
high (750). Obviously, the higher the chance of extraprostatic
extension, the less likely radical prostatectomy would be
recommended. "The clinician needs to decide what probability cut
point to use to manage patients," Dr. Miles says.
The optimized microvessel density analysis will be marketed as
BioStage Tumor Assessment Service and offered to physicians and
pathologists by Bard Diagnostic Sciences, Inc., Seattle.