Comparison of contemporary methods for estimating prostate tumour volume in pathological specimens

Machine learning-based analysis of a semi-automated PI-RADS v2.1 scoring for prostate cancer

Background

Prostate Imaging-Reporting and Data System version 2.1 (PI-RADS v2.1) was developed to standardize the interpretation of multiparametric MRI (mpMRI) for prostate cancer (PCa) detection. However, a significant inter-reader variability among radiologists has been found in the PI-RADS assessment. The purpose of this study was to evaluate the diagnostic performance of an in-house developed semi-automated model for PI-RADS v2.1 scoring using machine learning methods.

Methods

The study cohort included an MRI dataset of 59 patients (PI-RADS v2.1 score 2 = 18, score 3 = 10, score 4 = 16, and score 5 = 15). The proposed semi-automated model involved prostate gland and zonal segmentation, 3D co-registration, lesion region of interest marking, and lesion measurement. PI-RADS v2.1 scores were assessed based on lesion measurements and compared with the radiologist PI-RADS assessment. Machine learning methods were used to evaluate the diagnostic accuracy of the proposed model by classification of PI-RADS v2.1 scores.

Results

The semi-automated PI-RADS assessment based on the proposed model correctly classified 50 out of 59 patients and showed a significant correlation (r = 0.94, p < 0.05) with the radiologist assessment. The proposed model achieved an accuracy of 88.00% ± 0.98% and an area under the receiver-operating characteristic curve (AUC) of 0.94 for score 2 vs. score 3 vs. score 4 vs. score 5 classification and accuracy of 93.20 ± 2.10% and AUC of 0.99 for low score vs. high score classification using fivefold cross-validation.

Conclusion

The proposed semi-automated PI-RADS v2.1 assessment system could minimize the inter-reader variability among radiologists and improve the objectivity of scoring.

Comparison of malignancy and spatial distribution between latent and clinical prostate cancer: an 8-year biopsy study

Background

Current prostate cancer (PCa) screening may detect nonprogressive lesion, leading to overdiagnosis and overtreatment. The purpose of the present study is to investigate whether the tumor pathological origin of latent prostate cancer (lPCa) and clinical prostate cancer (cPCa) are consistent, and to verify the current clinically significant prostate cancer criteria.

Methods

Prostate specimens were obtained from postmortem autopsy between 2014 and 2021 and patients who went through radical prostatectomy from 2013 to 2021. The pathological characteristics and spatial distribution of the lPCa group and cPCa group were compared and analyzed through SPSS software with P < 0.05 representing statistical significant.

Results

In lPCa group, a total of 45 tumor lesions from 24 lPCa cases were included, 54.2% of lPCa patients were ISUP ≥ 2, 12.5% had tumor volume ≥ 0.5 ml, and 16.7% had extraprostatic extension (EPE). In cPCa group, there were a total of 429 tumor lesions in 126 cases, 92.1% of cPCa patients were ISUP ≥ 2, and 82.5% had tumor volume of ≥ 0.5 ml. 36.3% had EPE. LPCa and cPCa have the same spatial distribution characteristics, and no significant difference was detected between the anterior and posterior zone. Peripheral zone tumors were significantly more common than transitional zone tumors. Tumors in apical 1/3 and middle 1/3 were significantly more common than basal 1/3.

Conclusion

The malignancy of cPCa is significantly higher than that of lPCa, and the spatial distribution of cPCa and lPCa is consistent. ISUP grade 2 is not sufficient to determine clinical significance of tumor.

Diagnostic accuracy of 68 Ga-PSMA PET/MRI and multiparametric MRI in detecting index tumours in radical prostatectomy specimen

OBJECTIVE

To evaluate the diagnostic accuracy of the ⁶⁸ gallium (⁶⁸ Ga) prostate-specific membrane antigen (PSMA) positron emission tomography/magnetic resonance imaging (PET/MRI) and multiparametric MRI (mpMRI) by region-based comparison of index tumour localisations using histopathological tumour maps of patients who underwent radical prostatectomy because of clinically significant prostate cancer.

PATIENTS AND METHODS

The study included 64 patients who underwent radical prostatectomy after primary staging with mpMRI and ⁶⁸ Ga-PSMA PET/MRI. Diagnostic analysis was performed by dividing the prostate into four anatomic regions as left/right anterior and left/right posterior. The extension of the lesions in mpMRI and the pathological uptake in ⁶⁸ Ga-PSMA PET/MRI were matched separately for each region with the extension of the index tumour into each region.

RESULTS

The sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio, and the accuracy of mpMRI and ⁶⁸ Ga-PSMA PET/MRI are shown as 55.7%, 91.8%, 80.6%, 77.2%, 78.1%, and 60.8%, 94.3%, 86.8% 79.8%, 83.5%, respectively. ⁶⁸ Ga-PSMA PET/MRI has higher sensitivity and specificity compared with mpMRI. However, no statistically significant difference was found (P = .464). Combined imaging had significantly higher diagnostic accuracy compared with mpMRI and ⁶⁸ Ga-PSMA PET/MRI (change in AUC: 0.084 and 0.046, P < .001 and P = .028, respectively), while no statistically significant difference was found between mpMRI and ⁶⁸ Ga-PSMA PET/MRI (change in AUC: 0.038, P = .246).

CONCLUSION

⁶⁸ Ga-PSMA PET/MRI had higher clinical diagnostic accuracy in prostate cancer compared with mpMRI. Diagnostic accuracy was significantly increased in the combined use of both imaging modalities.

How accurately can multiparametric magnetic resonance imaging measure the tumour volume of a prostate cancer? Results of a systematic review

The tumour volume of a cancer within the prostate gland is commonly measured with multiparametric MRI. The measurement has a role in many clinical scenarios including focal therapy, but the accuracy of it has never been systematically reviewed. We included articles if they compared tumour volume measurements obtained by mpMRI with a reference volume measurement obtained after radical prostatectomy. Correlation and concordance statistics were summarised. A simple accuracy score was derived by dividing the given mean or median mpMRI volume by the histopathological reference volume. Factors affecting the accuracy were noted. Scores for potential bias and quality were calculated for each article. A total of 18 articles describing 1438 patients were identified. Nine articles gave Pearson's correlation scores, with a median value of 0.75 but the range was wide (0.42-0.97). A total of 11 articles reported mean values for volume while 9 reported median values. For all 18 articles, the mean or median values for MRI volumes were lower than the corresponding reference values suggesting consistent underestimation. For articles reporting mean and median values for volume, the median accuracy scores were 0.83 and 0.80, respectively. The accuracy was higher for tumours of greater volume, higher grade and when an endorectal coil was used. Accuracy did not seem to improve over time, with a 3 Tesla magnet or by applying a shrinkage factor to the reference measurement. Most studies showed evidence of at least moderate bias, and their quality was highly variable, but neither of these appeared to affect accuracy.

Histological characteristics of the largest and secondary tumors in radical prostatectomy specimens and implications for focal therapy

Background

Pathological features of prostate cancer in Korean men were analyzed to determine whether identification of tumor volume, Gleason score (GS), focality, and location using radical prostatectomy (RP) specimens can provide useful information for the application of focal therapy (hemiablation).

Methods

From January 2016 to December 2017, 913 patients who underwent RP at a single center were selected for analysis. Patients with prostate-specific antigen levels > 15 ng/mL or those who had received hormone therapy prior to surgery were excluded. Preoperative data and the number, volume, location, and GS of each tumor were recorded.

Results

Overall, 762 RP specimens were examined, and 1448 tumors were identified. The majority of the cases were multifocal (60.5%) and bilateral (82%) in nature. Among the 686 secondary tumors, 250 (36.4%) had a GS ≥7 and 122 (17.8%) had a tumor volume ≥ 0.5 mL. Among the 435 bilateral multifocal cases, secondary tumors on the lobes contralateral to the largest tumor were significant by volume (≥0.5 mL) in 91 (20.9%) cases and by grade (GS ≥7) in 179 (41.1%) cases. There were 102 (23.4%) tumors with a small tumor volume (< 0.5 mL) and Gleason pattern 4 on the lobe contralateral to the largest tumor.

Conclusions

Bilateral and multifocal tumors are a common feature and secondary tumors frequently exhibit clinically significant prostate cancer on RP specimens in Korea. In many cases, secondary tumors on the lobe contralateral to the largest tumor had a high GS and small tumor volume.

The transverse and vertical distribution of prostate cancer in biopsy and radical prostatectomy specimens

Background

Prostate biopsy is the most common method for the diagnosis of prostate cancer and the basis for further treatment. Confirmation using radical prostatectomy specimens is the most reliable method for verifying the accuracy of template-guided transperineal prostate biopsy. The study aimed to reveal the spatial distribution of prostate cancer in template-guided transperineal saturation biopsy and radical prostatectomy specimens.

Methods

Between December 2012 to December 2016, 171 patients were diagnosed with prostate cancer via template-guided transperineal prostate biopsy and subsequently underwent laparoscopic radical prostatectomy. The spatial distributions of prostate cancer were analyzed and the consistency of the tumor distribution between biopsy and radical prostatectomy specimens were compared.

Results

The positive rate of biopsy in the apex region was significantly higher than that of the other biopsy regions (43% vs 28%, P < 0.01). In radical prostatectomy specimens, the positive rate was highest at the region 0.9–1.3 cm above the apex, and it had a tendency to decrease towards the base. There was a significant difference in the positive rate between the cephalic and caudal half of the prostate (68% vs 99%, P < 0.01). There were no significant differences between the anterior and posterior zones for either biopsy or radical prostatectomy specimens.

Conclusion

The tumor spatial distribution generated by template-guided transperineal prostate biopsy was consistent with that of radical prostatectomy specimens in general. The positive rate was consistent between anterior and posterior zones. The caudal half of the prostate, especially the vicinity of the apex, was the frequently occurred site of the tumor.

Comparison of the accuracy of multiparametric magnetic resonance imaging (mpMRI) results with the final pathology findings for radical prostatectomy specimens in the detection of prostate cancer

AIMS

To assess the accuracy of multiparametric magnetic resonance imaging (mpMRI), used in conjunction with the Prostrate Imaging Reporting and Data System (PI-RADS), version 2, in the detection of prostate cancer (PCa), and to determine the extent of the efficacy of mpMRI as a screening test in biopsy-naïve patients.

METHODS

Retrospective analysis was conducted in 107 patients who underwent mpMRI prior to radical prostatectomy (RP) at a single institution. The mpMRI findings were reassessed using PI-RADS, version 2. A comparison was made between the histological findings for the RP specimens and the mpMRI results.

RESULTS

Unique histologically confirmed PCa foci (237) were identified in 107 patients. Overall, mpMRI sensitivity of 46% was found for PCa detection (110/237). The sensitivity, specificity and negative predictive value of mpMRI was 75.5%, 77.0% and 79.8%, respectively, for clinically significant cancer, and 75.7%, 77.7% and 79.5%, for pathological index tumors. A moderate and significant correlation was observed between a high PI-RADS score and a high pathological grade, tumor volume, index tumor status and clinically significant cancer status (all, P < 0.001, respectively). Pathological tumor volume was a significant predictor of PCa detection using mpMRI according to multivariate analysis. Using a cut-off value of 0.89 cc, the sensitivity and specificity of mpMRI for PCa detection were 0.87 and 0.65, respectively.

CONCLUSION

The mpMRI, used in conjunction with PI-RADS, was useful in detecting PCa and in predicting tumor aggressiveness. However, the detection of 20% of clinically significant cancer was missed using mpMRI. Thus, its inclusion in a triage test should be limited to selected biopsy-naïve patients.

Measurement of tumor volume is not superior to diameter for prediction of lymph node metastasis in early gastric cancer with minute submucosal invasion

Background/Aim

The current indication for endoscopic resection in early gastric cancer (EGC) with minute (< 500 µm) submucosal invasion is based on tumor diameter, which may be insufficient to predict lymph node metastasis (LNM). We investigated whether tumor volume might more accurately predict LNM in EGC with minute submucosal invasion.

Materials and Methods

Among patients who underwent gastrectomy for gastric cancer, 346 with well/moderately differentiated EGC with submucosal invasion <500 µm were evaluated. Three-dimensional tumor volume was calculated using an endoscopically resected specimen and compared with 1-dimensional tumor diameter. Predictive ability of tumor diameter or volume for LNM was evaluated using receiver operating characteristic curve analysis.

Results

Tumor diameter and volume predicted LNM with an area under the curve (AUC) of 0.567 and 0.589, respectively. AUC, sensitivity, specificity, positive and negative predictive values, and accuracy of the 2 models were not significantly different. Tumor diameter ≥ 3 cm showed a significant association with LNM (odds ratio [OR], 2.57; 95% confidence interval [CI], 1.01–6.57; P = 0.049), whereas a tumor volume cutoff value of 752.8 cm3 showed no significant association with LNM (OR, 1.52; 95% CI, 0.59–3.88; P = 0.385).

Conclusions

Tumor volume had no advantage over diameter for predicting LNM in well/moderately differentiated EGC with minute submucosal invasion.

Tumour heterogeneity poses a significant challenge to cancer biomarker research

BACKGROUND

The high degree of genomic diversity in cancer represents a challenge for identifying objective prognostic markers. We aimed to examine the extent of tumour heterogeneity and its effect on the evaluation of a selected prognostic marker using prostate cancer as a model.

METHODS

We assessed Gleason Score (GS), DNA ploidy status and phosphatase and tensin homologue (PTEN) expression in radical prostatectomy specimens (RP) from 304 patients followed for a median of 10 years (interquartile range 6-12). GS was assessed for every tumour-containing block and DNA ploidy for a median of four samples for each RP. In a subgroup of 40 patients we assessed DNA ploidy and PTEN status in every tumour-containing block. In 102 patients assigned to active surveillance (AS), GS and DNA ploidy were studied in needle biopsies.

RESULTS

Extensive heterogeneity was observed for GS (89% of the patients) and DNA ploidy (40% of the patients) in the cohort, and DNA ploidy (60% of the patients) and PTEN expression (75% of the patients) in the subgroup. DNA ploidy was a significant prognostic marker when heterogeneity was taken into consideration. In the AS cohort we found heterogeneity in GS (24%) and in DNA ploidy (25%) specimens.

CONCLUSIONS

Multi-sample analysis should be performed to support clinical treatment decisions.

Performance characteristics of prostate-specific antigen density and biopsy core details to predict oncological outcome in patients with intermediate to high-risk prostate cancer underwent robot-assisted radical prostatectomy

Background

Many urologic surgeons refer to biopsy core details for decision making in cases of localized prostate cancer (PCa) to determine whether an extended resection and/or lymph node dissection should be performed. Furthermore, recent reports emphasize the predictive value of prostate-specific antigen density (PSAD) for further risk stratification, not only for low-risk PCa, but also for intermediate- and high-risk PCa. This study focused on these parameters and compared respective predictive impact on oncologic outcomes in Japanese PCa patients.

Methods

Two-hundred and fifty patients with intermediate- and high-risk PCa according to the National Comprehensive Cancer Network (NCCN) classification, that underwent robot-assisted radical prostatectomy at a single institution, and with observation periods of longer than 6 months were enrolled. None of the patients received hormonal treatments including antiandrogens, luteinizing hormone-releasing hormone analogues, or 5-alpha reductase inhibitors preoperatively. PSAD and biopsy core details, including the percentage of positive cores and the maximum percentage of cancer extent in each positive core, were analyzed in association with unfavorable pathologic results of prostatectomy specimens, and further with biochemical recurrence. The cut-off values of potential predictive factors were set through receiver-operating characteristic curve analyses.

Results

In the entire cohort, a higher PSAD, the percentage of positive cores, and maximum percentage of cancer extent in each positive core were independently associated with advanced tumor stage ≥ pT3 and an increased index tumor volume > 0.718 ml. NCCN classification showed an association with a tumor stage ≥ pT3 and a Gleason score ≥8, and the attribution of biochemical recurrence was also sustained. In each NCCN risk group, these preoperative factors showed various associations with unfavorable pathological results. In the intermediate-risk group, the percentage of positive cores showed an independent predictive value for biochemical recurrence. In the high-risk group, PSAD showed an independent predictive value.

Conclusions

PSAD and biopsy core details have different performance characteristics for the prediction of oncologic outcomes in each NCCN risk group. Despite the need for further confirmation of the results with a larger cohort and longer observation, these factors are important as preoperative predictors in addition to the NCCN classification for a urologic surgeon to choose a surgical strategy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12894-017-0238-y) contains supplementary material, which is available to authorized users.

Comparison of free-hand transperineal mpMRI/TRUS fusion-guided biopsy with transperineal 12-core systematic biopsy for the diagnosis of prostate cancer: a single-center prospective study in China

OBJECTIVES

To prospectively compare biopsy outcomes between free-hand transperineal mpMRI/TRUS fusion targeted biopsy (TB) and transperineal systematic biopsy (SB) in patients with first prostate biopsy.

PATIENTS AND METHODS

In all, 224 consecutive patients with the suspicion of PCa were investigated. All patients were evaluated by 3.0-T mpMRI applying the ESUR criteria. All patients underwent free-hand transperineal mpMRI/TRUS fusion TB and additionally a transperineal SB. Pathological findings of TB, SB, and step-sectioned RP specimens were analyzed.

RESULTS

The median age of the patients was 69 (40-85) years, median PSA level was 10.05 (3.61-78.39) ng/mL, and median prostate volume was 45.5 (22-77) mL. Overall, the PCa detection rate was 50.45% (113/224). TB detected significantly more cancer [44.2% (99/224) vs. 34.8% (78/224); P = 0.001] and clinically significant PCa [75.75% (75/99) vs. 62.82% (49/78); P = 0.005] than SB. For the upgrading of Gleason score, 39.74% (31/78), more clinically significant PCa was detected by using additional TB than by SB alone. Conversely, 5.05% (5/99) more clinically significant PCa was found by SB in addition to that by TB. The location of 96.67% (58/60) and Gleason score of 60% (36/60) of TB-proven ITs were correctly identified, as corroborated by RP specimens. The median IT volume was 1.125 (0.21-19.87) ml on MRI and 1.41 (0.13-9.56) ml in RP specimens.

CONCLUSIONS

Free-hand transperineal mpMRI/TRUS fusion biopsy was associated with a higher detection rate of clinically significant PCa while taking fewer cores. Moreover, this technique can reliably predict the location, and relatively reliably predict cancer volume and Gleason score of ITs.

Lesion volume predicts prostate cancer risk and aggressiveness: validation of its value alone and matched with prostate imaging reporting and data system score

OBJECTIVE

To demonstrate the association between magnetic resonance imaging (MRI) estimated lesion volume (LV), prostate cancer detection and tumour clinical significance, evaluating this variable alone and matched with Prostate Imaging Reporting and Data System version 2 (PI-RADS v2) score.

PATIENTS AND METHODS

We retrospectively analysed 157 consecutive patients, with at least one prior negative systematic prostatic biopsy, who underwent transperineal prostate MRI/ultrasonography fusion-targeted biopsy between January 2014 and February 2016. Suspicious lesions were delineated using a 'region of interest' and the system calculated prostate volume and LV. Patients were divided in groups considering LV (≤0.5, 0.5-1, ≥1 mL) and PI-RADS score (1-5). We considered clinically significant prostate cancer as all cancers with a Gleason score of ≥3 + 4 as suggested by PI-RADS v2. A direct comparison between MRI estimated LV (MRI LV) and histological tumour volume (HTV) was done in 23 patients who underwent radical prostatectomy during the study period. Differences between MRI LV and HTV were assessed using the paired sample t-test. MRI LV and HTV concordance was verified using a Bland-Altman plot. The chi-squared test and logistic and ordinal regression models were used to evaluate difference in frequencies.

RESULTS

The MRI LV and PI-RADS score were associated both with prostate cancer detection (both P < 0.001) and with significant prostate cancer detection (P < 0.001 and P = 0.008, respectively). When the two variables were matched, increasing LV increased the risk within each PI-RADS group. Prostate cancer detection was 1.4-times higher for LVs of 0.5-1 mL and 1.8-times higher for LVs of ≥1 mL; significant prostate cancer detection was 2.6-times for LVs of 0.5-1 mL and 4-times for LVs of ≥1 mL. There was a positive correlation between MRI LV and HTV (r = 0.9876, P < 0.001). Finally, Bland-Altman analysis showed that MRI LV was underestimated by 4.2% compared to HTV. Study limitations include its monocentric and retrospective design and the limited cohort.

CONCLUSIONS

This study demonstrates that PI-RADS score and the MRI LV, independently and in combination, are associated with prostate cancer detection and with tumour clinical significance.

Is negative multiparametric magnetic resonance imaging really able to exclude significant prostate cancer? The real-life experience

OBJECTIVES

To evaluate the histopathological results after radical prostatectomy (RP) in patients that had normal preoperative multiparametric magnetic resonance imaging (mpMRI), in order to determine whether they had significant or insignificant disease. Moreover, we evaluated the influence of the expertise of the radiologist on the results.

PATIENTS AND METHODS

We retrospectively included patients who underwent RP in our centre and who had a preoperative negative mpMRI. The MRIs were considered negative when no suspicious lesion was seen or when the Prostate Imaging Reporting and Data System version 1 score was <7. We used Pathological tumour-node-metastasis staging and Gleason score on pathology reports, and whole-mount sections to calculate tumour volume.

RESULTS

We identified 101 patients from 2009 to 2015. Final pathology showed that 16.9% had extraprostatic extension, 13.8% had primary Gleason pattern 4 (4 + 3 and above), 47.5% had secondary Gleason pattern 4 or 5, and 55.9% and 20.6% had a main tumour volume of ≥0.5 and ≥2 mL, respectively. When limiting the analysis to expert reading only, the numbers improved: only one patient (3.4%) had extraprostatic extension (P < 0.05), one patient (3.4%) had primary Gleason pattern 4 (P = 0.05), and 64.7% and 5.9% had a main tumour volume of ≥0.5 and ≥2 mL, respectively (P = 0.01).

CONCLUSION

A negative MRI does not guarantee the absence of significant prostate cancer.

A Novel System for Estimating Residual Disease and Pathologic Response to Neoadjuvant Treatment of Prostate Cancer

BACKGROUND

Pathologic variables that characterize response of prostate carcinoma to current neoadjuvant therapy have not been characterized in detail. This study reports (i) the histological features of prostate cancer treated with abiraterone and enzalutamide and inter-pathologist variance in identifying these features, and (ii) the effect of the novel androgen deprivation agents on residual cancer volume.

METHODS

We reviewed sections of prostatectomies from 37 patients treated with neoadjuvant agents and 22 untreated patients, tabulated the frequency of nine features of cancer (intact cancer glands, isolated cancer cells, poorly formed glands, cribriform architecture, clear spaces, intraductal carcinoma, solid sheets of cancer cells, prominent nucleoli, and previously described ABC grouping) and two features of benign glands (prominent basal cells and coalescent corpora amylacea). We used several methods, including a novel metric (visual grid system), to estimate residual tumor volume.

RESULTS

The most highly reproducible features were ABC grouping (κ = 0.56-0.7), presence of intraductal carcinoma (κ = 0.34-0.72), cribriform architecture (κ = 0.42-0.68), solid sheets of tumor cells (κ = 0.44-0.56), and coalescent corpora amylacea (κ = 0.4-0.54). Among poorly reproducible features were prominent nucleoli (κ = 0.03-0.11), clear spaces (κ = 0.05-0.07), and poorly formed cancer glands (κ = 0.02-0.1). Determination of tumor mass was excellent regardless of the method used-maximum tumor size (κ = 0.9-0.94), tumor area (κ = 0.94-0.96), and grid-based tumor cellularity (κ = 0.9).

CONCLUSIONS

We propose using a set of parameters including maximum tumor size, tumor area/volume, cellularity, volume, and ABC grouping for evaluating radical prostatectomies post-neoadjuvant therapy. Prostate 76:1285-1292, 2016. © 2016 Wiley Periodicals, Inc.

Prostate cancer volume estimations based on transrectal ultrasonography-guided biopsy in order to predict clinically significant prostate cancer

INTRODUCTION

Tumor diameter is a reliable parameter to estimate tumor volume in solid organ cancers; its use in prostate cancer is controversial since it exhibits a more irregular pattern of growth. This study aimed to examine the association between the tumor volume estimations based on transrectal ultrasound (TRUS) guided biopsy results and the tumor volume measured on the pathological specimen.

MATERIALS AND METHODS

A total of 237 patients who underwent radical retropubic prostatectomy (RRP) were included in this retrospective study. The differences and correlations between cancer volume estimations based on TRUS guided biopsy findings and cancer volume estimations based on post-prostatectomy pathology specimens were examined. In addition, diagnostic value of TRUS guided biopsy-based volume estimations in order to predict clinically significant cancer (>0.5 cc) were calculated.

RESULTS

The mean cancer volume estimated using TRUS biopsy results was lower (5.5±6.5 cc) than the mean cancer volume calculated using prostatectomy specimens (6.4±7.6 cc) (p<0.041).TRUS guided biopsy examination resulted in 5 false positive and 15 false negative cases. There was a significant but weak correlation between the two parameters (r=0.62, p<0.001). The sensitivity and specificity of TRUS guided biopsy in predicting the presence of clinically significant cancer was 93.4% (95% CI, 89.1-96.1) and 50.0% (95% CI, 20.1-79.9), respectively.

CONCLUSIONS

TRUS guided biopsy-derived estimations seem to have a limited value to predict pathologically established tumor volume. Further studies are warranted to identify additional methods that may more accurately predict actual pathological characteristics and prognosis of prostate cancer.

Prostate Cancer Volume Estimation by Combining Magnetic Resonance Imaging and Targeted Biopsy Proven Cancer Core Length: Correlation with Cancer Volume

PURPOSE

Multiparametric magnetic resonance imaging often underestimates or overestimates pathological cancer volume. We developed what is to our knowledge a novel method to estimate prostate cancer volume using magnetic resonance/ultrasound fusion, biopsy proven cancer core length.

MATERIALS AND METHODS

We retrospectively analyzed the records of 81 consecutive patients with magnetic resonance/ultrasound fusion, targeted biopsy proven, clinically localized prostate cancer who underwent subsequent radical prostatectomy. As 7 patients each had 2 visible lesions on magnetic resonance imaging, 88 lesions were analyzed. The dimensions and estimated volume of visible lesions were calculated using apparent diffusion coefficient maps. The modified formula to estimate cancer volume was defined as the formula of vertical stretching in the anteroposterior dimension of the magnetic resonance based 3-dimensional model, in which the imaging estimated lesion anteroposterior dimension was replaced by magnetic resonance/ultrasound targeted, biopsy proven cancer core length. Agreement of pathological cancer volume with magnetic resonance estimated volume or the novel modified volume was assessed using a Bland-Altman plot.

RESULTS

Magnetic resonance/ultrasound fusion, biopsy proven cancer core length was a stronger predictor of the actual pathological cancer anteroposterior dimension than magnetic resonance estimated lesion anteroposterior dimension (r = 0.824 vs 0.607, each p <0.001). Magnetic resonance/ultrasound targeted, biopsy proven cancer core length correlated with pathological cancer volume (r = 0.773, p <0.001). The modified formula to estimate cancer volume demonstrated a stronger correlation with pathological cancer volume than with magnetic resonance estimated volume (r = 0.824 vs 0.724, each p <0.001). Agreement of modified volume with pathological cancer volume was improved over that of magnetic resonance estimated volume on Bland-Altman plot analysis. Predictability was more enhanced in the subset of lesions with a volume of 2 ml or less (ie if spherical, the lesion was approximately 16 mm in diameter).

CONCLUSIONS

Combining magnetic resonance estimated cancer volume with magnetic resonance/ultrasound fusion, biopsy proven cancer core length improved cancer volume predictability.

Detection of the index tumour and tumour volume in prostate cancer using T2-weighted and diffusion-weighted magnetic resonance imaging (MRI) alone

OBJECTIVE

To examine the performance of T2-weighted (T2W) and diffusion-weighted (DW) magnetic resonance imaging (MRI) for detecting the index tumour in patients with prostate cancer and to examine the agreement between MRI and histology when assessing tumour volume (TV) and overall tumour burden.

PATIENTS AND METHODS

The study included 199 consecutive patients with biopsy confirmed prostate cancer randomised to MRI before radical prostatectomy from December 2009 to July 2012. MRI-detected tumours (MRTs) were ranked from 1 to 3 according to decreasing volume and were compared with histologically detected tumours (HTs) ranked from 1 to 3, with HT 1 = index tumour. Whole-mount section histology was used as a reference standard. The TVs of true-positive MRTs (MRTVs 1-3) were compared with the TVs found by histology (HTVs 1-3). All tumours were registered on a 30-sector map and by classifying each sector as positive/negative, the rate of true-positive and -negative sectors was calculated.

RESULTS

The detection rate for the HT 1 (index tumour) was 92%; HT 2, 45%; and HT 3, 37%. The MRTV 1-3 vs the HTV 1-3 were 2.8 mL vs 4.0 mL (index tumour, P < 0.001), 1.0 mL vs 0.9 mL (tumour 2, P = 0.413), and 0.6 mL vs 0.5 mL (tumour 3, P = 0.492). The rate of true-positive and -negative sectors was 50% and 88%, κ = 0.39.

CONCLUSION

A combination of T2W and DW MRI detects the index tumour in 92% of cases, although MRI underestimates both TV and tumour burden compared with histology.

Predictive value of magnetic resonance imaging determined tumor contact length for extracapsular extension of prostate cancer

PURPOSE

Tumor contact length is defined as the amount of prostate cancer in contact with the prostatic capsule. We evaluated the ability of magnetic resonance imaging determined tumor contact length to predict microscopic extracapsular extension compared to existing predictors of extracapsular extension.

MATERIALS AND METHODS

We retrospectively analyzed the records of 111 consecutive patients with magnetic resonance imaging/ultrasound fusion targeted, biopsy proven prostate cancer who underwent radical prostatectomy from January 2010 to July 2013. Median patient age was 64 years and median prostate specific antigen was 8.9 ng/ml. Clinical stage was cT1 in 93 cases (84%) and cT2 in 18 (16%). Postoperative pathological analysis confirmed pT2 in 71 patients (64%) and pT3 in 40 (36%). We evaluated 1) in the radical prostatectomy specimen the correlation of microscopic extracapsular extension with pathological cancer volume, pathological tumor contact length and Gleason score, 2) the correlation between microscopic extracapsular extension and magnetic resonance imaging tumor contact length, and 3) the ability of preoperative variables to predict microscopic extracapsular extension.

RESULTS

Logistic regression analysis revealed that pathological tumor contact length correlated better with microscopic extracapsular extension than the predictive power of pathological cancer volume (0.821 vs 0.685). The Spearman correlation between pathological and magnetic resonance imaging tumor contact length was r = 0.839 (p <0.0001). ROC AUC analysis revealed that magnetic resonance imaging tumor contact length outperformed cancer core involvement on targeted biopsy and the Partin tables to predict microscopic extracapsular extension (0.88 vs 0.70 and 0.63, respectively). At a magnetic resonance imaging tumor contact length threshold of 20 mm the accuracy for diagnosing microscopic extracapsular extension was superior to that of conventional magnetic resonance imaging criteria (82% vs 67%, p = 0.015). We developed a predicted probability plot curve of extracapsular extension according to magnetic resonance imaging tumor contact length.

CONCLUSIONS

Magnetic resonance imaging determined tumor contact length could be a promising quantitative predictor of microscopic extracapsular extension.