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Prostate Cancer
Table 2: Sensitivity and Specificity of Different Imaging Figure 2: HistoScanning Visualisation of Extraprostatic Extension
Technologies for Detecting Prostate Cancer
Technology Dynamic Realtime Power Doppler Contrast-enhanced
Contrast-enhanced Elastography
11
Ultrasound
11
ADF Doppler
23
MRI
22
Study Prostate cancer Raised PSA Raised PSA Raised PSA
Population patients
Reference Radical prostatectomy Systematic biopsy Systematic biopsy Systematic biopsy
Method histology (transperineal) (transperineal) (transrectal)
Tumour >0.2cc >0.5cc – – –
Volume
Sens. 77% 90% 68% 70% 100%
Spec. 91% 88% 81% 75% 48%
Acc. – – 76% 73% –
Outcomes PPV 86% 77% – – –
NPV 85% 95% – – –
required to verify HistoScanning against step-sectioned
MRI = magnetic resonance imaging; ADF = advanced dynamic flow; PSA = prostate-specific
histopathology. Unconventional sagittal step-sectioning of the
antigen; PPV = positive predictive value; NPV = negative predictive value; Sens. = sensitivity;
Spec. = specificity; Acc. = accuracy. prostate allowed for more accurate correlation to the sagittal
ultrasound scan, but made it difficult to sample the lateral margins of
Before it can be used routinely, the reliability and clinical value of any the gland. As a result of the sagittal sectioning, the urethra was not
new diagnostic method must be firmly established. The first step available as an ‘anchor’ for the registration of the HistoScanning
towards obtaining the level of evidence needed to establish prostate against the histological grids. This may have resulted in some
HistoScanning’s potential was to explore and define its accuracy in registration inaccuracies. There are no clear criteria for what
locating and sizing prostate lesions compared with the most reliable constitutes one lesion. When is differentiated tissue one lesion, and
reference test, step-sectioned histology.
24,25
The population studied when is it two or more? There appears to be no clear consensus on
consisted of 29 men diagnosed with prostate cancer that was thought which is the most appropriate measure for comparing the index and
to be confined to the prostate and was clinically attributed to T1c- reference tests. There is no clear guide concerning total tumour
stage cancer and who were scheduled for radical prostatectomy. All volume, number and volume of index and satellite lesions or even
patients were subjected to HistoScanning prior to surgery. Data from when cancer is clinically ‘significant’.
15 of the patients were used to refine the HistoScanning analysis
algorithms, and HistoScanning analysis was performed ‘blind’ on the Future Studies
remaining 14 patients without knowledge of the histology results. Further multicentre studies in larger pertinent study populations are
(Data from one of the 14 patients was excluded from the final analysis being implemented to both confirm the findings of the initial studies
due to damaged histology samples.) and further explore HistoScanning’s capabilities and performance
under different clinical conditions. In order to establish the true
The results showed that prostate HistoScanning was able to accurately: sensitivity and specificity of the test, the ideal study population consists
of men presenting with high PSA in whom no biopsy has been
• distinguish all cancer lesions ≥0.5cc from background tissue; performed. However, the challenge is to find an accurate reference
• determine lesion location (100% concordance in determining focality test approaching the sensitivity and specificity of step-sectioned
and laterality of the lesions); and histology. As standard biopsies sample less than 5% of prostate tissue,
• estimate lesion size – prostate HistoScanning predictions correlate it is unsuitable for this purpose. Therefore, template saturation
closely with tumour volume as determined by planimetry at histology biopsies need to be considered as the reference test.
(r=0.97; p<0.0001).
All future studies will apply HistoScanning to the unprocessed RF volume
Furthermore, there were indications that prostate HistoScanning may source data rather than the processed greyscale ultrasound data. It is
also be helpful for staging. For example, extraprostatic extension (EPE) hoped that the vastly larger volume of data obtained this way will allow
was predicted in all cases that were later confirmed by histology (see prostate HistoScanning to assess tumour aggressiveness, a major
Figure 2). determinant of whether a tumour focus is considered clinically relevant.
Limitations of the Published Studies Participant Perspectives on the Potential Clinical Value of
The first studies had certain methodological shortcomings, most of Prostate HistoScanning
which will be addressed in ongoing and future studies. HistoScanning After the above presentations, the discussion was opened up to the
analysis was based on standardised greyscale ultrasound volume files colloquium participants and the faculty. Professor Fitzpatrick
rather than the unprocessed RF volume files, which contain two orders encouraged the participants to share their thoughts about clinically
of magnitude more data. The study population was relatively small and relevant potential uses, and also raise their questions and concerns
from a single centre (where a population screening programme was about the HistoScanning technology. The areas where the participants
yet to be implemented). Patients were all known to have prostate perceived HistoScanning to potentially offer the most benefit are
cancer and were scheduled for radical prostatectomy. This was outlined below.
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