Diagnostic ultrasound ( PDFDrive )

CHAPTER 10 The Prostate and Transrectal Ultrasound 399
SV
T
T
A
B
FIG. 10.12 Staging of Extensive Prostate Cancer. (A) Stage T3A cancer (T) has extended outside the prostate at the neurovascular bundle
(arrows). Note how dificult it is to differentiate tumor extension from the normal irregularity caused by the neurovascular bundle. (B) Stage T3C
(parasagittal view) cancer (T) extending (arrows) into the seminal vesicles (SV).
prostate, SVs, and lymph nodes and is more accurate for prognosis.
Clinical staging (designated as cT_) is important for deciding
management but is less accurate than histologic evaluation
(designated as pathologic stage pT_) of the prostate and surrounding
tissues because DRE and imaging modalities have
limitations in predicting extraprostatic extension and 60% to
90% of tumors are multifocal. Compared with pathologic evaluation,
clinical understaging occurs in about 40% to 60% and
overstaging in about 5%.
Staging with imaging is used selectively in high-risk groups
using isotope bone scans, CT, and mpMRI. When the risk of
extraprostatic disease is low, consideration is given to avoidance
of these tests to reduce radiation exposure and costs. It is estimated
that in the current PSA era over 90% of cases are localized,
obviating need for routine staging by CT, MRI, or bone scan at
initial diagnosis. Recommendations for staging by imaging difer
among organizations. In general, bone scans are recommended
for men with PSA above 10 to 20 ng/mL, Gleason score of 8 or
higher, or symptoms. Sot tissue imaging with CT, MRI, or
PET-CT is recommended for cT3 or cT4 cancers, nomogram
risks of extensive disease exceeding 10%, and men with
symptoms. 104,105
Neither of the current imaging modalities, MRI or TRUS, is
completely accurate in predicting extracapsular extent (ECE)
or SV involvement, but they are superior to clinical assessment.
106 MRI appears superior to TRUS because TRUS is
operator dependent. In experienced hands MRI performance
characteristics are sensitivity, 65%; speciicity, 73%; PPV, 88%;
and negative predictive value (NPV), 38%. SV invasion gauged
by altered shape and signal has sensitivity of 83% and speciicity
of 99%. Detection of node involvement is typically not possible
with TRUS but is similar for CT and MRI, with sensitivity
of 7%, speciicity of 100%, PPV of 85%, and NPV of 100%.
However a normal CT or MRI scan does not exclude nodal
involvement. 90
TRUS indings suggesting ECE are similar to MRI indings
and include capsule bulge or distortion, asymmetry of neurovascular
bundle, and obliteration of rectoprostatic angle. SV
invasion is suggested by visible extension into or a mass in the
SV (Fig. 10.12). In very experienced hands TRUS was shown to
be as accurate as MRI for determining ECE (area under curve
for TRUS of 0.81 vs. MRI, 0.71) 107 and superior to nomograms
that predict stage. 108 However, experience and equipment appear
to be important, and overall reported TRUS accuracy in determining
ECE ranges as follows: sensitivity, 12% to 90%; speciicity,
46% to 91%; PPV, 46% to 85%; NPV, 38%; and SV invasion
sensitivity, 9% to 60%, and speciicity, 82% to 100%. 109 Because
imaging has limitations for preoperative staging, many physicians
rely on their clinical acumen or use multifactorial staging
nomograms (e.g., Kattan, Partin) that make use of DRE, PSA,
Gleason score, and other variables. 6,106,110,111 However, experienced
physicians have found meticulous TRUS to be more accurate
than DRE and tables for staging 108 (see Fig. 10.12).
Remember also that although 95% of malignant prostate
tumors are adenocarcinomas, the remaining 5% are unusual
tumors of many cell types that do not elevate PSA. hese frequently
afect younger patients in whom the initial symptoms
are those of metastatic disease including urinary dysfunction
and skeletal pain. At imaging they mimic locally extensive and
metastatic prostate cancer. 72,112
Histologic grading describing the microscopic pathologic
spectrum of prostate adenocarcinoma was devised by Dr. Donald
Gleason in the 1960s and updated in 2014. It uses ive progressive
histologic patterns of gland disorganization to assign a Gleason
pattern 1 through 5, which correlates with tumor aggression.
Most prostate cancers are heterogeneous and display several
patterns. he two most prevalent patterns are added to give a
score (e.g., primary pattern 4 and secondary pattern 3 give a
Gleason score of 4 + 3 = 7/10). Recently patterns 1 and 2 and
scores of 5 or lower were eliminated, so currently scores range
from 6 to 10. 59,73,113
Recently Gleason score 3 + 3 = 6, speciically pattern 3, has
come under discussion as to its malignant and aggressive potential
and clinical importance. In the current PSA era Gleason 6 is
the most commonly diagnosed score at biopsy and accounts for
about 49% of cases. Although Gleason 3 + 3 = 6 demonstrates
many visible characteristics of malignancy including local invasion
and molecular and genetic markers, its clinical behavior