Establishing the pathways and indications for performing isotope bone scans in newly diagnosed intermediate-risk localised prostate cancer - results from a large contemporaneous cohort

ACR Appropriateness Criteria® Pretreatment Detection, Surveillance, and Staging of Prostate Cancer: 2022 Update

Prostate cancer is second leading cause of death from malignancy after lung cancer in American men. The primary goal during pretreatment evaluation of prostate cancer is disease detection, localization, establishing disease extent (both local and distant), and evaluating aggressiveness, which are the driving factors of patient outcomes such as recurrence and survival. Prostate cancer is typically diagnosed after the recognizing elevated serum prostate-specific antigen level or abnormal digital rectal examination. Tissue diagnosis is obtained by transrectal ultrasound-guided biopsy or MRI-targeted biopsy, commonly with multiparametric MRI without or with intravenous contrast, which has recently been established as standard of care for detecting, localizing, and assessing local extent of prostate cancer. Although bone scintigraphy and CT are still typically used to detect bone and nodal metastases in patients with intermediate- or high-risk prostate cancer, novel advanced imaging modalities including prostatespecific membrane antigen PET/CT and whole-body MRI are being more frequently utilized for this purpose with improved detection rates. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Diagnostic and cost‐effectiveness of axial skeleton MRI in staging high‐risk prostate cancer

Introduction

Current literature suggests that axial skeleton magnetic resonance imaging (AS-MRI) is more sensitive than Tc 99m bone scintigraphy (BS) for detecting bone metastases (BM) in high-risk prostate cancer (PCa). However, BS is still widely performed. Its diagnostic accuracy has been studied; however, its feasibility and cost implications are yet to be examined.

Methods

We reviewed all patients with high risk PCa undergoing AS-MRI over a 5-year period. AS-MRI was performed on patients with histologically confirmed PCa and either PSA > 20 ng/ml, Gleason ≥8, or TNM Stage ≥T3 or N1 disease. All AS-MRI studies were obtained using a 1.5-T AchievaPhilips™MRI scanner. We compared the AS-MRI positivity and equivocal rate with that of BS. Data were analysed according to Gleason score, T-stage and PSA. Multivariate logistic regression analyses were used to quantify the strength of association between positive scans and clinical variables. Feasibility and burden of expenditure was also evaluated.

Results

Five hundred three patients with a median age of 72 and a mean PSA of 34.8 ng/ml were analysed. Eighty-eight patients (17.5%) were positive for BM on AS-MRI (mean PSA 99 [95% CI 69.1-129.9]). Comparatively 409 patients (81.3%) were negative for BM on AS-MRI (mean PSA 24.7 (95% CI [21.7-27.7]) (p = 0.007); 1.2% (n = 6) of patients had equivocal results (mean PSA 33.4 [95% CI 10.5-56.3]). There was no significant difference in age (p = 0.122) between this group and patients with a positive scan, but there was a significant difference in PSA (p = 0.028), T stage (p = 0.006) and Gleason score (p = 0.023). In comparison with BS, AS-MRI detection rate was equivalent or higher compared with the literature. Based on NHS tariff calculations, there would be a minimum cost saving of £8406.89. All patients underwent AS-MRI within 14 days.

Conclusion

The use of AS-MRI to stage BM in high-risk PCa is both feasible and results in a reduced burden of expenditure.

Validating the screening criteria for bone metastases in treatment-naïve unfavorable intermediate and high-risk prostate cancer - the prevalence and location of bone- and lymph node metastases

OBJECTIVE

The European Association of Urology (EAU) recommends a bone scan for newly diagnosed unfavorable intermediate- and high-risk prostate cancer. We aimed to validate the screening criteria for bone metastases in patients with treatment-naïve prostate cancer.

METHODS

This single-center retrospective study included all patients with treatment-naïve unfavorable intermediate- or high-risk prostate cancer. All underwent MRI of the lumbar column (T2Dixon) and pelvis (3DT2w, DWI, and T2 Dixon). The presence and location of lymph node and bone metastases were registered according to risk groups and radiological (rad) T-stage. The risk of lymph node metastases was assessed by odds ratio (OR).

RESULTS

We included 390 patients, of which 68% were high-risk and 32% were unfavorable intermediate-risk. In the high-risk group, the rate of regional- and non-regional lymph node metastases was 11% and 6%, respectively, and the rate of bone metastases was 10%. In the unfavorable intermediate-risk group, the rate of regional- and non-regional lymph node metastases was 4% and 0.8%, respectively, and the rate of bone metastases was 0.8%. Metastases occurred exclusively in the lumbar column in 0.5% of all patients, in the pelvis in 4%, and the pelvis and lumbar column in 3%. All patients with bone metastases had radT3-4, and patients with radT3-4 showed a four-fold increased risk of lymph node metastases (OR 4.48, 95% CI: 2.1-9.5).

CONCLUSION

Bone metastases were found in 10% with high-risk prostate cancer and 0.8% with unfavorable intermediate-risk. Therefore, we question the recommendation to screen the unfavorable intermediate-risk group for bone metastases.

KEY POINTS

• The rate of bone metastases was 10% in high-risk patients and 0.8% in the unfavorable intermediate-risk group. • The rate of lymph-node metastases was 17% in high-risk patients and 5% in the unfavorable intermediate-risk group. • No bone metastases were seen in radiologically localized disease.

Comparison of Bone Uptake in Bone Scan and Ga-68 PSMA PET/CT Images in Patients with Prostate Cancer

OBJECTIVE

The aim of this study was to compare images from Tc-99m MDP bone scan (BS) and Ga-68 PSMA PET/CT of patients with prostate cancer in terms of bone metastases.

METHODS

Overall, 34 patients exhibited a mean age of 66 ± 9.5 (50-88) years, mean PSA of 51 ± 159ng/ml (0-912), and mean Gleason score of 8 (6-9). BS and Ga-68 PSMA PET/CT were applied to 34 patients within 30 days, and the results were evaluated, retrospectively. In both tests, radiopharmaceutical uptake in bones were compared.

RESULTS

In 7 patients (20.5%), uptake was not significant on BS and Ga-68 PSMA PET / CT images, which is related to metastasis. In 14 (41%) patients, bone metastases were observed in both examinations. However, more metastatic lesions were observed in the Ga-68 PSMA PET/CT of 3 patients and in the bone scintigraphy of 2 patients. PSMA expression was not observed on Ga-68 PSMA PET / CT in 13 (38%) patients with increased activity in bone scintigraphy. Two (6%) of these patients were thought to be metastatic, 2 (6%) were suspicious for metastasis, and 9 (26%) had no metastasis. When a lesion-based evaluation was performed, a total of 480 activities were evaluated: increased activity uptake was found in 305 BS, and 427 PSMA expression activity was detected. Furthermore, 435 of these activities were evaluated as metastatic.

CONCLUSION

Ga-68 PSMA PET/CT provides an additional contribution to the BS evaluation of activity areas because of the presence of PSMA expression and anatomical lesions. In 6% of the patients, activity on BS and metastatic appearance in CT images were observed and the presence of lesions in the absence of PSMA was determined. This suggests that bone metastases without PSMA expression may also be present.

Rationalising bone scan usage in prostate cancer staging – A UK nationwide audit of the BAUS Radical Prostatectomy (RP) database

Objective:

With new evidence showing no need to perform staging bone scans (BS) in intermediate-risk prostate cancer (PC), we reviewed the practice and trends of performing BS in PC patients across the United Kingdom by analysing a cohort of PC patients from the British Association of Urological Surgeons (BAUS) radical prostatectomy (RP) database. We analysed the database as such for data entry and regional trends.

Materials and methods:

Between 2007 and 2016, patients who had BS were categorised according to D’Amico risk categories as low (LR), intermediate (IR) and high (HR). The IR group was subdivided into primary patterns 3 (IR3) and 4 (IR4). Subgroup analysis based on prostate-specific antigen and Gleason score was performed. Regional trends regarding data entry and no staging scans before RP were also analysed.

Results:

Over the study period, the database included 39,382 patients. The quality of data improved from 2011. A consistent drop in proportion of LR patients who had BS was noted over the study period which stood at less than 1% in 2016. This parallels an increase in proportion of HR patients, but the IR3 and IR4 proportion remained stable throughout the study. A large proportion of HR patients were deemed HR because of clinical T stage in the subgroup analysis. A progressive drop is noted in patients having no scan before RP, which stood at 3.66% in 2016. Out of 15 regions, 13 showed improvement in data completeness.

Conclusion:

In the United Kingdom, good adherence with guidelines to avoid BS in LR patients is noted but is still continued in IR. Updating the guidelines which are still not uniform and involvement of specialist multidisciplinary teams to reflect these would help reduce a considerable number of unnecessary BS being performed. Regional trends shown would help relevant centres to review their data entry process and potentially improve them.

Level of evidence:

not applicable for this multicentre audit.

Development and validation of a prediction model for identifying men with intermediate- or high-risk prostate cancer for whom bone imaging is unnecessary: a nation-wide population-based study

Objective: To develop and validate a nomogram that identifies men for whom bone scan is unnecessary.Material and methods: The study datasets were derived from the National Prostate Cancer Register (NPCR) of Sweden. All men in the NPCR ≤80 years of age who were diagnosed with intermediate- or high-risk prostate cancer and who had pretreatment bone imaging (^99mTc MDP scintigraphy, plain x-ray, computed tomography, magnetic resonance imaging, and/or positron emission tomography fused with computed tomography) were included. Men diagnosed from 2015-2016 formed a development dataset and men diagnosed in 2017 formed a validation dataset. Outcome was metastasis on bone imaging as registered in NPCR. Multivariable logistic regression was used to develop a nomogram.Results: In the development dataset 482/5084 men (10%) had bone metastasis, the corresponding percentage in the validation dataset was 282/2554 (11%). Gleason grade group, clinical T stage, and prostate-specific antigen were included in the final model. Discrimination and calibration were satisfactory in both the development (AUC 0.80, 95% CI 0.78-0.82) and validation dataset (AUC 0.80, 95% CI, 0.77-0.82). Compared with using the EAU guidelines' recommendation for selecting men for imaging, using the nomogram with a cut-off at 4% chance of bone metastasis, would have avoided imaging in 519/2068 men (25%) and miss bone metastasis in 10/519 (2%) men in the validation dataset.Conclusion: By use of our nomogram, bone scans of men with prostate cancer can be avoided in a large proportion of men.

Comparison of orthogonal NLP methods for clinical phenotyping and assessment of bone scan utilization among prostate cancer patients

OBJECTIVE

Clinical care guidelines recommend that newly diagnosed prostate cancer patients at high risk for metastatic spread receive a bone scan prior to treatment and that low risk patients not receive it. The objective was to develop an automated pipeline to interrogate heterogeneous data to evaluate the use of bone scans using a two different Natural Language Processing (NLP) approaches.

MATERIALS AND METHODS

Our cohort was divided into risk groups based on Electronic Health Records (EHR). Information on bone scan utilization was identified in both structured data and free text from clinical notes. Our pipeline annotated sentences with a combination of a rule-based method using the ConText algorithm (a generalization of NegEx) and a Convolutional Neural Network (CNN) method using word2vec to produce word embeddings.

RESULTS

A total of 5500 patients and 369,764 notes were included in the study. A total of 39% of patients were high-risk and 73% of these received a bone scan; of the 18% low risk patients, 10% received one. The accuracy of CNN model outperformed the rule-based model one (F-measure = 0.918 and 0.897 respectively). We demonstrate a combination of both models could maximize precision or recall, based on the study question.

CONCLUSION

Using structured data, we accurately classified patients' cancer risk group, identified bone scan documentation with two NLP methods, and evaluated guideline adherence. Our pipeline can be used to provide concrete feedback to clinicians and guide treatment decisions.