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BACKGROUND: The delineation of intraprostatic lesions is vital for correct delivery of focal radiotherapy boost in patients with prostate cancer (PC). Errors in the delineation could translate into reduced tumour control and potentially increase the side effects. The purpose of this study is to compare PET-based delineation methods with histopathology.

MATERIALS AND METHODS: The study population consisted of 15 patients with confirmed high-risk PC intended for prostatectomy. [68Ga]-PSMA-PET/MR was performed prior to surgery. Prostate lesions identified in histopathology were transferred to the in vivo [68Ga]-PSMA-PET/MR coordinate system. Four radiation oncologists manually delineated intraprostatic lesions based on PET data. Various semi-automatic segmentation methods were employed, including absolute and relative thresholds, adaptive threshold, and multi-level Otsu threshold.

RESULTS: The gross tumour volumes (GTVs) delineated by the oncologists showed a moderate level of interobserver agreement with Dice similarity coefficient (DSC) of 0.68. In comparison with histopathology, manual delineations exhibited the highest median DSC and the lowest false discovery rate (FDR) among all approaches. Among semi-automatic approaches, GTVs generated using standardized uptake value (SUV) thresholds above 4 (SUV > 4) demonstrated the highest median DSC (0.41), with 0.51 median lesion coverage ratio, FDR of 0.66 and the 95th percentile of the Hausdorff distance (HD95%) of 8.22 mm.

INTERPRETATION: Manual delineations showed a moderate level of interobserver agreement. Compared to histopathology, manual delineations and SUV > 4 exhibited the highest DSC and the lowest HD95% values. The methods that resulted in a high lesion coverage were associated with a large overestimation of the size of the lesions.

Background: Should early response imaging predict tumor response to therapy, personalized treatment adaptations could be feasible to improve outcome or reduce the risk of adverse events. This prospective single-center observational study on 2-fluorine-18-fluoro-deoxy-glucose (2-[18F]FDG) positron-emission tomography/magnetic resonance imaging (PET/MRI) features aims to investigate the association between semantic 2-[18F]FDG-PET/MRI imaging parameters and outcome prediction in uterine cervical squamous cell carcinoma (CSCC) treated with radiotherapy.

Results: Eleven study participants with previously untreated CSCC were examined with 2-[18F]FDG-PET/MRI at baseline and approximately one week after start of curative radiotherapy. All study participants had at least 24 months clinical follow-up. Two patients relapsed during the follow-up period. Reduced tumor size according to visual assessment was present in 9/11 participants (median change in sum of largest diameters (SLD) − 10.4%; range − 2.5 to − 24.6%). The size reduction was less pronounced in the relapse group compared to the no relapse group, with median change in SLD − 4.9%, versus − 10.4%. None of the reductions qualified as significantly reduced or increased in size according to RECIST 1.1., hence all participants were at this stage classified as non-responders/stable disease. Median baseline functional tumor volume (FTV) for the relapse group was 126 cm3, while for the no relapse group 9.3 cm3. Median delta FTV in the relapse group was 50.7 cm3, representing an actual increase in metabolically active volume, while median delta FTV in the no relapse group was − 2.0 cm3. Median delta apparent diffusion coefficient (ADC) was lower in the relapse group versus the no relapse group (− 3.5 mm2/s vs. 71 mm2/s).

Conclusions: Early response assessment with 2-[18F]FDG-PET/MRI identified potentially predictive functional imaging biomarkers for prediction of radiotherapy outcome in CSCC, that could not be recognized with tumor measurements according to RECIST 1.1. These biomarkers (delta FTV and delta ADC) should be further evaluated.

OBJECTIVES: To investigate the cumulative incidence proportion of disseminated or local Bacillus Calmette-Guérin (BCG) infections after adjuvant BCG instillations in patients with non-muscle-invasive bladder cancer (NMIBC).

PATIENTS AND METHODS: We analysed the timing and occurrence of BCG infections and absolute and relative risk in relation to patient characteristics available in the Swedish nationwide database 'BladderBaSe 2.0'. The cumulative incidence proportion of a BCG infection was indicated by a reported diagnosis of tuberculosis (TB) in the patient registry or filing a prescription for tuberculostatic drugs.

RESULTS: The cumulative incidence proportion was 1.1% at the 5-year follow-up in 5033 patients exposed to adjuvant BCG instillations. The incidence rate was highest during the first 2 years after start of BCG instillations. Women had a lower risk than men (hazard ratio 0.23, 95% confidence interval 0.07-0.74). Age and calendar time at diagnosis, comorbidity, tumour risk group, previous medication with corticosteroids, immunosuppressive drugs, or time between transurethral resection of the bladder tumour and commencing the adjuvant BCG instillation were not associated with risk.

CONCLUSIONS: These data further supports that the overall risk of a BCG infection after BCG-instillation treatment for NMIBC is low. The great majority of infections occur in the first 2 years, calling for an awareness of the diverse symptoms of BCG infection during this period. We provide evidence for male sex as a risk factor; however, the statistical precision is low and with a risk of selection bias, making it difficult to rule out the other suggested risk factors without further studies with different approaches.

OBJECTIVE: To report national data on diagnostics and treatment of upper tract urothelial carcinoma (UTUC) from the Swedish National Registry of Urinary Bladder Cancer (SNRUBC).

PATIENTS AND METHODS: Data from 2015 to 2021 were retrieved, and descriptive analyses were performed regarding incidence, diagnostic modalities, preoperative tumor staging, quality indicators for treatment including the use of standardized care pathways (SCP) and multidisciplinary tumor boards (MDTB). Time trends were explored for the study period.

RESULTS: Registrations included 1,213 patients with renal pelvic cancer and 911 patients with ureteric cancer with a median age of 74 (interquartile range [IQR] 70-77) and 75 (IQR 71-78) years, respectively. Incidence rates of UTUC were stable, as were proportions of curative treatment intent. Median number of days from referral to treatment was 76 (IQR 57-99) and 90 (IQR 72-118) days, respectively, for tumors of the renal pelvis and ureter, which remained unchanged after introduction of SCP in 2016. Noticeable trends included stable use of kidney-sparing surgery and increased use of MDTB. For radical nephroureterectomy (RNU), robot-assisted technique usage increased even for non-organ-confined tumors (cT3-4) and in one out of three patients undergoing RNU a bladder cuff excision was not registered.

CONCLUSIONS: The population-based SNRUBC with high coverage contributes to the knowledge about UTUC with granular and generalizable data. The present study reveals a high proportion of patients not subjected to curatively intended treatment and suggests unmet needs to shorten lead times to treatment and use of bladder cuff excision when performing radical surgery for UTUC in Sweden.

Background and purpose: Dose escalation in external radiotherapy of prostate cancer shows promising results in terms of biochemical disease-free survival. Boost volume delineation guidelines are sparse which may cause high interobserver variability. The aim of this research was to characterize gross tumor volume (GTV) delineations based on multiparametric magnetic resonance imaging (mpMRI) and prostate specific membrane antigen-positron emission tomography (PSMA-PET) in relation to histopathology-validated Gleason grade 4 and 5 regions.

Material and methods: The study participants were examined with [68Ga]PSMA-PET/mpMRI prior to radical prostatectomy. Four radiation oncologists delineated GTVs in 15 study participants, on four different image types; T2-weighted (T2w), diffusion weighted imaging (DWI), dynamic contrast enhanced (DCE) and PSMA-PET scans separately. The simultaneous truth and performance level estimation (STAPLE) algorithm was used to generate combined GTVs. GTVs were subsequently compared to histopathology. We analysed how Dice similarity coefficient (DSC) and lesion coverage are affected by using single versus multiple image types as well as by adding a clinical target volume (CTV) margin.

Results: Median DSC (STAPLE) for different GTVs varied between 0.33 and 0.52. GTVPSMA-PET/mpMRI generated the highest median lesion coverage at 0.66. Combining different image types achieved similar lesion coverage as adding a CTV margin to contours from a single image type, while reducing non-malignant tissue inclusion within the target volume.

Conclusion: The combined use of mpMRI or PSMA-PET/mpMRI shows promise, achieving higher DSC and lesion coverage while minimizing non-malignant tissue inclusion, in comparison to the use of a single image type with an added CTV margin.

Introduction: Real-life data on vismodegib in advanced basal cell carcinoma (aBCC) are limited. Optimal treatment duration is left to the discretion of the physician.

Objectives: To assess the effectiveness, safety and treatment pattern for vismodegib in aBCC in clinical practice.

Methods: In this multicenter, non-interventional, prospective study, 49 Swedish patients planned for vismodegib treatment were included. The treatment pattern observed was treatment until remission, allowing unlimited discontinuations/pauses.

Results: The majority of patients (93.8%), discontinued at least once during the study. Compared to earlier studies there was a decrease of more than 2 months with actual drug intake, reducing the patients burden and costs, at the same time as a high number of responses were seen (87.8%). Median progression-free-survival was 16.7 months, and 90% of the patients were alive at 13.3 months. Ten patients were re-challenged with vismodegib at recurrence or progression, resulting in five partial remissions and three complete remissions.

Conclusions: Clinical response rates with vismodegib for aBCC were comparable to those of similar trials despite a shorter and more intermittent treatment duration. The majority of re-challenges lead to partial or complete remissions.

Objective: PET/CT and multiparametric MRI (mpMRI) are important diagnostic tools in clinically significant prostate cancer (csPC). The aim of this study was to compare csPC detection rates with [⁶⁸Ga]PSMA-11-PET (PSMA)-PET, [¹¹C] Acetate (ACE)-PET, and mpMRI with histopathology as reference, to identify the most suitable imaging modalities for subsequent hybrid imaging. An additional aim was to compare inter-reader variability to assess reproducibility.

Methods: During 2016–2019, all study participants were examined with PSMA-PET/mpMRI and ACE-PET/CT prior to radical prostatectomy. PSMA-PET, ACE-PET and mpMRI were evaluated separately by two observers, and were compared with histopathology-defined csPC. Statistical analyses included two-sided McNemar test and index of specific agreement.

Results: Fifty-five study participants were included, with 130 histopathological intraprostatic lesions >0.05 cc. Of these, 32% (42/130) were classified as csPC with ISUP grade ≥2 and volume >0.5 cc. PSMA-PET and mpMRI showed no difference in performance (P = 0.48), with mean csPC detection rate of 70% (29.5/42) and 74% (31/42), respectively, while with ACE-PET the mean csPC detection rate was 37% (15.5/42). Interobserver agreement was higher with PSMA-PET compared to mpMRI [79% (26/33) vs 67% (24/38)]. Including all detected lesions from each pair of observers, the detection rate increased to 90% (38/42) with mpMRI, and 79% (33/42) with PSMA-PET.

Conclusion: PSMA-PET and mpMRI showed high csPC detection rates and superior performance compared to ACE-PET. The interobserver agreement indicates higher reproducibility with PSMA-PET. The combined result of all observers in both PSMA-PET and mpMRI showed the highest detection rate, suggesting an added value of a hybrid imaging approach.

BACKGROUND: Perirectal spacers may be beneficial to reduce rectal side effects from radiotherapy (RT). Here, we present the impact of a hyaluronic acid (HA) perirectal spacer on rectal dose as well as spacer stability, long-term gastrointestinal (GI) and genitourinary (GU) toxicity and patient-reported outcome (PRO).

METHODS: In this phase II study 81 patients with low- and intermediate-risk prostate cancer received transrectal injections with HA before external beam RT (78 Gy in 39 fractions). The HA spacer was evaluated with MRI four times; before (MR0) and after HA-injection (MR1), at the middle (MR2) and at the end (MR3) of RT. GI and GU toxicity was assessed by physician for up to five years according to the RTOG scale. PROs were collected using the Swedish National Prostate Cancer Registry and Prostate cancer symptom scale questionnaires.

RESULTS: There was a significant reduction in rectal V70% (54.6 Gy) and V90% (70.2 Gy) between MR0 and MR1, as well as between MR0 to MR2 and MR3. From MR1 to MR2/MR3, HA thickness decreased with 28%/32% and CTV-rectum space with 19%/17% in the middle level. The cumulative late grade ≥ 2 GI toxicity at 5 years was 5% and the proportion of PRO moderate or severe overall bowel problems at 5 years follow-up was 12%. Cumulative late grade ≥ 2 GU toxicity at 5 years was 12% and moderate or severe overall urinary problems at 5 years were 10%.

CONCLUSION: We show that the HA spacer reduced rectal dose and long-term toxicity.

Background: The value of fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for TN staging in head and neck cancer (HNC) has been proven in numerous studies. A few studies have investigated the value of FDG-PET/magnetic resonance imaging (MRI) in the staging of HNC; the combined results indicate potential for FDG-PET/MRI, but the scientific evidence remains weak.

Purpose: To compare performance of FDG-PET/CT and FDG-PET/MRI for locoregional staging in patients with oropharyngeal carcinomas.

Material and Methods: Two radiologists independently of each other retrospectively reviewed primary pre-therapeutic FDG-PET/CT and FDG-PET/MRI examinations from 40 individuals with oropharyngeal carcinomas. TN stage and primary tumor size were noted. The results were compared between observers and modalities and against TN stage set at a multidisciplinary conference.

Results: For nodal staging, PET/MRI had slightly higher specificity and accuracy than PET/CT for the most experienced observer. Both methods demonstrated excellent sensitivity (≥ 0.97 and 1.00, respectively), as well as high negative predictive values (≥ 0.95 and 1.00, respectively). No significant differences were found for tumor staging or measurement of maximum tumor diameter. There was a weak agreement (κ = 0.35–0.49) between PET/CT and PET/MRI for T and N stages for both observers. Inter-observer agreement was higher for PET/MRI than for PET/CT, both for tumor staging (κ = 0.57 vs. 0.35) and nodal staging (κ = 0.69 vs. 0.55). The agreement between observers was comparable to the agreement between methods.

Conclusion: PET/MRI may be a viable alternative to PET/CT for locoregional staging (TN staging) and assessment of maximal tumor diameter in oropharyngeal squamous cell cancer.

Background: Intravesical recurrence (IVR) after surgery for upper tract urothelial carcinoma (UTUC) is a clinical problem. We investigated if preoperative invasive diagnostic modalities (IDM) such as antegrade/retrograde uretero-pyelography and/or selective urine cytology/barbotage, and URS with or without concomitant biopsy are associated with IVR after radical surgery for UTUC. Risk of death from urothelial cancer and all causes was investigated as secondary outcomes.

Methods: We investigated a population-based cohort of 1038 consecutive patients subjected to radical surgery for UTUC 2015–2019 in Sweden, using the Bladder Cancer Data Base Sweden (BladderBaSe 2.0), comprising all patients in the Swedish National Registry of Urinary Bladder Cancer. Risk estimates of IVR, death from urothelial cancer, and all causes was assessed using multivariable Cox regression models.

Results: The study included 536 cases with and 502 without preoperative IDM. IDM was associated with increased risk of IVR (HR 1.24, 95% CI 1.03–1.52) and risk of urothelial cancer death (HR 1.56, CI 1.12–2.18), compared to no IDM after a median follow-up of 1.3 yrs. Stratified analysis for tumor location showed that IDM was associated with risk of IVR in ureteric cancer (HR 1.66, 95% CI 1.21–2.28) but not in renal pelvic cancer (HR 1.07, 95% CI 0.81–1.41). Limitations included the observational setting and the lack of variables such as tumour grade, multifocality and preoperative hydronephrosis.

Conclusions: Worse outcomes for patients subjected to preoperative IDM highlight the need for carefully considering diagnostic decisions for UTUC patients, specifically in tumours located in the ureter.