Epidemiological description and trajectories of patients with prostate cancer in Denmark: an observational study of 7448 patients

OBJECTIVE

Identification of patients at high risk of aggressive prostate cancer is a major clinical challenge. With the view of developing artificial intelligence-based methods for identification of these patients, we are constructing a comprehensive clinical database including 7448 prostate cancer (PCa) Danish patients. In this paper we provide an epidemiological description and patients' trajectories of this retrospective observational population, to contribute to the understanding of the characteristics and pathways of PCa patients in Denmark.

RESULTS

Individuals receiving a PCa diagnosis during 2008-2014 in Region Southern Denmark were identified, and all diagnoses, operations, investigations, and biochemistry analyses, from 4 years prior, to 5 years after PCa diagnosis were obtained. About 85.1% were not diagnosed with metastatic PCa during the study period (unaggressive PCa); 9.2% were simultaneously diagnosed with PCa and metastasis (aggressive-advanced PCa), while 5.7% were not diagnosed with metastatic PCa at first, but they were diagnosed with metastasis at some point during the 5 years follow-up (aggressive-not advanced PCa). Patients with unaggressive PCa had more clinical investigations directly related to PCa detection (prostate ultrasounds and biopsies) during the 4 years prior to PCa diagnosis, compared to patients with aggressive PCa, which may have contributed to the early detection of PCa.

Artificial intelligence-based measurements of PET/CT imaging biomarkers are associated with disease-specific survival of high-risk prostate cancer patients

OBJECTIVE

Artificial intelligence (AI) offers new opportunities for objective quantitative measurements of imaging biomarkers from positron-emission tomography/computed tomography (PET/CT). Clinical image reporting relies predominantly on observer-dependent visual assessment and easily accessible measures like SUV_max, representing lesion uptake in a relatively small amount of tissue. Our hypothesis is that measurements of total volume and lesion uptake of the entire tumour would better reflect the disease`s activity with prognostic significance, compared with conventional measurements.

METHODS

An AI-based algorithm was trained to automatically measure the prostate and its tumour content in PET/CT of 145 patients. The algorithm was then tested retrospectively on 285 high-risk patients, who were examined using ¹⁸F-choline PET/CT for primary staging between April 2008 and July 2015. Prostate tumour volume, tumour fraction of the prostate gland, lesion uptake of the entire tumour, and SUV_max were obtained automatically. Associations between these measurements, age, PSA, Gleason score and prostate cancer-specific survival were studied, using a Cox proportional-hazards regression model.

RESULTS

Twenty-three patients died of prostate cancer during follow-up (median survival 3.8 years). Total tumour volume of the prostate (p = 0.008), tumour fraction of the gland (p = 0.005), total lesion uptake of the prostate (p = 0.02), and age (p = 0.01) were significantly associated with disease-specific survival, whereas SUV_max (p = 0.2), PSA (p = 0.2), and Gleason score (p = 0.8) were not.

CONCLUSION

AI-based assessments of total tumour volume and lesion uptake were significantly associated with disease-specific survival in this patient cohort, whereas SUV_max and Gleason scores were not. The AI-based approach appears well-suited for clinically relevant patient stratification and monitoring of individual therapy.

Percutaneous tibial nerve stimulation for idiopathic and neurogenic overactive bladder dysfunction: a four-year follow-up single-centre experience

OBJECTIVE

Overactive bladder (OAB) affects hundreds of millions of people worldwide and has significant detrimental effects on quality-of-life. Percutaneous tibial nerve stimulation (PTNS) is endorsed in the European guidelines of Urology as second-line therapy - on par with pharmacological treatment for women with OAB.

METHODS

This prospective cohort study describes our clinical experience with PTNS in a daily outpatient clinic, on a consecutive cohort. The cohort of 116 patients was mixed; including both men and women with idiopathic (iOAB) and neurogenic (nOAB) overactive bladder. Patients were treated with a 12-week course of PTNS followed by monthly maintenance treatment. Data were collected during 4 years.

RESULTS

The most common indication for PTNS was OAB with urge incontinence (53%) followed by OAB-dry and nocturia (both 16%). One hundred and ten (95%) patients completed follow-up and 68 patients (62%) continued to maintenance treatment. A total of 68 patients reported an effect on PROM, BD and ICIQ-OAB, which is the same 62% that continue in maintenance PTNS. A significant decline was seen in overall ICIQ-OAB score, with a median drop from 87 to 54, a significant decline in overall frequency and nocturia on bladder diary and a shift in pad test group in 19% of the incontinence patients.

CONCLUSION

PTNS shows an equally significant effect on men as well as women both in the iOAB and nOAB subgroups in a daily outpatient clinic. In our opinion, PTNS should be a standard treatment option available at urological departments, where both men and women in both sub-groups could benefit from treatment. Further randomized studies focusing on men with iOAB are needed.

Chemical modification of proteins by insertion of synthetic peptides using tandem protein trans-splicing

Manipulation of proteins by chemical modification is a powerful way to decipher their function. However, most ribosome-dependent and semi-synthetic methods have limitations in the number and type of modifications that can be introduced, especially in live cells. Here, we present an approach to incorporate single or multiple post-translational modifications or non-canonical amino acids into proteins expressed in eukaryotic cells. We insert synthetic peptides into GFP, NaV1.5 and P2X2 receptors via tandem protein trans-splicing using two orthogonal split intein pairs and validate our approach by investigating protein function. We anticipate the approach will overcome some drawbacks of existing protein enigineering methods.

Deep learning-based quantification of PET/CT prostate gland uptake: association with overall survival

Aim

To validate a deep‐learning (DL) algorithm for automated quantification of prostate cancer on positron emission tomography/computed tomography (PET/CT) and explore the potential of PET/CT measurements as prognostic biomarkers.

Material and methods

Training of the DL‐algorithm regarding prostate volume was performed on manually segmented CT images in 100 patients. Validation of the DL‐algorithm was carried out in 45 patients with biopsy‐proven hormone‐naïve prostate cancer. The automated measurements of prostate volume were compared with manual measurements made independently by two observers. PET/CT measurements of tumour burden based on volume and SUV of abnormal voxels were calculated automatically. Voxels in the co‐registered ¹⁸F‐choline PET images above a standardized uptake value (SUV) of 2·65, and corresponding to the prostate as defined by the automated segmentation in the CT images, were defined as abnormal. Validation of abnormal voxels was performed by manual segmentation of radiotracer uptake. Agreement between algorithm and observers regarding prostate volume was analysed by Sørensen‐Dice index (SDI). Associations between automatically based PET/CT biomarkers and age, prostate‐specific antigen (PSA), Gleason score as well as overall survival were evaluated by a univariate Cox regression model.

Results

The SDI between the automated and the manual volume segmentations was 0·78 and 0·79, respectively. Automated PET/CT measures reflecting total lesion uptake and the relation between volume of abnormal voxels and total prostate volume were significantly associated with overall survival (P = 0·02), whereas age, PSA, and Gleason score were not.

Conclusion

Automated PET/CT biomarkers showed good agreement to manual measurements and were significantly associated with overall survival.

3D skeletal uptake of 18F sodium fluoride in PET/CT images is associated with overall survival in patients with prostate cancer

BACKGROUND

Sodium fluoride (NaF) positron emission tomography combined with computer tomography (PET/CT) has shown to be more sensitive than the whole-body bone scan in the detection of skeletal uptake due to metastases in prostate cancer. We aimed to calculate a 3D index for NaF PET/CT and investigate its correlation to the bone scan index (BSI) and overall survival (OS) in a group of patients with prostate cancer.

METHODS

NaF PET/CT and bone scans were studied in 48 patients with prostate cancer. Automated segmentation of the thoracic and lumbar spines, sacrum, pelvis, ribs, scapulae, clavicles, and sternum were made in the CT images. Hotspots in the PET images were selected using both a manual and an automated method. The volume of each hotspot localized in the skeleton in the corresponding CT image was calculated. Two PET/CT indices, based on manual (manual PET index) and automatic segmenting using a threshold of SUV 15 (automated PET15 index), were calculated by dividing the sum of all hotspot volumes with the volume of all segmented bones. BSI values were obtained using a software for automated calculations.

RESULTS

BSI, manual PET index, and automated PET15 index were all significantly associated with OS and concordance indices were 0.68, 0.69, and 0.70, respectively. The median BSI was 0.39 and patients with a BSI >0.39 had a significantly shorter median survival time than patients with a BSI <0.39 (2.3 years vs not reached after 5 years of follow-up [p = 0.01]). The median manual PET index was 0.53 and patients with a manual PET index >0.53 had a significantly shorter median survival time than patients with a manual PET index <0.53 (2.5 years vs not reached after 5 years of follow-up [p < 0.001]). The median automated PET15 index was 0.11 and patients with an automated PET15 index >0.11 had a significantly shorter median survival time than patients with an automated PET15 index <0.11 (2.3 years vs not reached after 5 years of follow-up [p < 0.001]).

CONCLUSIONS

PET/CT indices based on NaF PET/CT are correlated to BSI and significantly associated with overall survival in patients with prostate cancer.

Added value of cost-utility analysis in simple diagnostic studies of accuracy: (18)F-fluoromethylcholine PET/CT in prostate cancer staging

Diagnostic studies of accuracy targeting sensitivity and specificity are commonly done in a paired design in which all modalities are applied in each patient, whereas cost-effectiveness and cost-utility analyses are usually assessed either directly alongside to or indirectly by means of stochastic modeling based on larger randomized controlled trials (RCTs). However the conduct of RCTs is hampered in an environment such as ours, in which technology is rapidly evolving. As such, there is a relatively limited number of RCTs. Therefore, we investigated as to which extent paired diagnostic studies of accuracy can be also used to shed light on economic implications when considering a new diagnostic test. We propose a simple decision tree model-based cost-utility analysis of a diagnostic test when compared to the current standard procedure and exemplify this approach with published data from lymph node staging of prostate cancer. Average procedure costs were taken from the Danish Diagnosis Related Groups Tariff in 2013 and life expectancy was estimated for an ideal 60 year old patient based on prostate cancer stage and prostatectomy or radiation and chemotherapy. Quality-adjusted life-years (QALYs) were deduced from the literature, and an incremental cost-effectiveness ratio (ICER) was used to compare lymph node dissection with respective histopathological examination (reference standard) and (18)F-fluoromethylcholine positron emission tomography/computed tomography (FCH-PET/CT). Lower bounds of sensitivity and specificity of FCH-PET/CT were established at which the replacement of the reference standard by FCH-PET/CT comes with a trade-off between worse effectiveness and lower costs. Compared to the reference standard in a diagnostic accuracy study, any imperfections in accuracy of a diagnostic test imply that replacing the reference standard generates a loss in effectiveness and utility. We conclude that diagnostic studies of accuracy can be put to a more extensive use, over and above a mere indication of sensitivity and specificity of an imaging test, and that health economic considerations should be undertaken when planning a prospective diagnostic accuracy study. These endeavors will prove especially fruitful when comparing several imaging techniques with one another, or the same imaging technique using different tracers, with an independent reference standard for the evaluation of results.

Spine metastases in prostate cancer: comparison of technetium-99m-MDP whole-body bone scintigraphy, [(18) F]choline positron emission tomography(PET)/computed tomography (CT) and [(18) F]NaF PET/CT

OBJECTIVE

To compare the diagnostic accuracy of the following imaging techniques in the detection of spine metastases, using magnetic resonance imaging (MRI) as a reference: whole-body bone scintigraphy (WBS) with technetium-99m-MDP, [18F]-sodium fluoride (NaF) positron emission tomography (PET)/computed tomography (CT) and [(18) F]-fluoromethylcholine (FCH) PET/CT.

PATIENTS AND METHODS

The study entry criteria were biopsy-proven prostate cancer, a positive WBS consistent with bone metastases, and no history of androgen deprivation. Within 30 days of informed consent, trial scans were performed in random order. Scans were interpreted blindly for the purpose of a lesion-based analysis. The primary target variable was bone lesion (malignant/benign) and the 'gold standard' was MRI.

RESULTS

A total of 50 men were recruited between May 2009 and March 2012. Their mean age was 73 years, their median PSA level was 84 ng/mL, and the mean Gleason score of the tumours was 7.7. A total of 46 patients underwent all four scans, while four missed one PET/CT scan. A total of 526 bone lesions were found in the 50 men: 363 malignant and 163 non-malignant according to MRI. Sensitivity, specificity, positive and negative predictive values and accuracy were: WBS: 51, 82, 86, 43 and 61%; NaF-PET/CT: 93, 54, 82, 78 and 81%; and FCH-PET/CT: 85, 91, 95, 75 and 87%, respectively.

CONCLUSIONS

We found that FCH-PET/CT and NaF-PET/CT were superior to WBS with regard to detection of prostate cancer bone metastases within the spine. The present results call into question the use of WBS as the method of choice in patients with hormone-naïve prostate cancer.

[18F]fluoromethylcholine (FCH) positron emission tomography/computed tomography (PET/CT) for lymph node staging of prostate cancer: a prospective study of 210 patients

Study Type--Diagnostic (exploratory cohort) Level of Evidence 2a. What's known on the subject? and What does the study add? Staging of patients with prostate cancer is the cornerstone of treatment. However, after curative intended therapy a high portion of patients relapse with local and/or distant recurrence. Therefore, one may question whether surgical lymph node dissection (LND) is sufficiently reliable for staging of these patients. Several imaging methods for primary LN staging of patients with prostate cancer have been tested. Acceptable detection rates have not been achieved by CT or MRI or for that matter with PET/CT using the most common tracer fluoromethylcholine (FCH). Other more recent metabolic tracers like acetate and choline seem to be more sensitive for assessment of LNs in both primary staging and re-staging. However, previous studies were small. Therefore, we assessed the value of [(18) F]FCH PET/CT for primary LN staging in a prospective study of a larger sample and with a 'blinded' review. After a study period of 3 years and >200 included patients, we concluded that [(18) F]FCH PET/CT did not reach an optimal detection rate compared with LND, and, therefore, it cannot replace this procedure. However, we did detect several bone metastases with [(18) F]FCH PET/CT that the normal bone scans had missed, and this might be worth pursuing.

OBJECTIVES

• To assess the value of [(18) F]fluoromethylcholine (FCH) positron emission tomography/computed tomography (PET/CT) for lymph node (LN) staging of prostate cancer. • To evaluate if FCH PET/CT can replace LN dissection (LND) for LN staging of prostate cancer, as about one-third of patients with prostate cancer who receive intended curative therapy will have recurrence, one reason being undetected LN involvement.

PATIENTS AND METHODS

• From January 2008 to December 2010, 210 intermediate- or high-risk patients had a FCH PET/CT scan before regional LND. • After dissection, the result of histological examination of the LNs (gold standard) was compared with the result of FCH PET/CT obtained by 'blinded review'. • Sensitivity, specificity, positive (PPV), and negative predictive values (NPV) of FCH PET/CT were measured for detection of LNe metastases.

RESULTS

• Of the 210 patients, 76 (36.2%) were in the intermediate-risk group and 134 (63.8%) were in the high-risk group. A medium (range) of 5 (1-28) LNs were removed per patient. • Histological examination of removed LNs showed metastases in 41 patients. Sensitivity, specificity, PPV, and NPV of FCH PET/CT for patient-based LN staging were 73.2%, 87.6%, 58.8% and 93.1%, respectively. • Corresponding values for LN-based analyses were 56.2%, 94.0%, 40.2%, and 96.8%, respectively. • The mean diameter of the true positive LN metastases was significantly larger than that of the false negative LNs (10.3 vs 4.6 mm; P < 0.001). • In addition, FCH PET/CT detected a high focal bone uptake, consistent with bone metastases, in 18 patients, 12 of which had histologically benign LNs.

CONCLUSIONS

• Due to a relatively low sensitivity and a correspondingly rather low PPV, FCH PET/CT is not ideal for primary LN staging in patients with prostate cancer. • However, FCH PET/CT does convey important additional information otherwise not recognised, especially for bone metastases.