Optimal contouring of seminal vesicle for definitive radiotherapy of localized prostate cancer: comparison between EORTC prostate cancer radiotherapy guideline, RTOG0815 protocol and actual anatomy

Seminal Vesicle Treatment for Localized Prostate Cancer Treated with External Beam Radiotherapy

This study retrospectively reviewed data from men with localized prostate cancer treated with external beam radiotherapy (EBRT). We identified 359 men with localized prostate cancer treated with curative EBRT at the Cross Cancer Institute between 2010-2011. The volume of seminal vesicles (SVs) treated as well as dose values were extracted. These volumes were compared to gold standard contours drawn by a trained expert based on consensus European Society for Radiotherapy and Oncology (ESTRO) contouring guidelines. Patient and tumor characteristics were extracted for these patients. Memorial Sloan Kettering prostate cancer nomogram was used to assign a predicted risk of SV involvement for each patient based on baseline tumor characteristics. In patients with a predicted risk of SV involvement greater than 15% (n = 184), 86.5% (SD = 18.6) of the base of the SVs were treated with EBRT, compared to 66.7% (SD = 32.6) for patients with a predicted risk of SV involvement less than 15% (n = 175, p < 0.0001). Similarly, the mean percentage of proximal and total SV volumes treated with EBRT was 75.6% (SD = 24.4) and 68.7% (SD = 26.0) for patients with a predicted risk of SV involvement of greater than 15%, compared to 50.3% (SD = 31.0, p < 0.0001) and 41.0% (SD = 27.8, p < 0.0001) for patients with a risk of less than 15%. The results indicate that all parts of the SVs are more likely to be contoured in men with >15% risk of SV involvement than those with <15% risk. However, radiation oncologists still contour a high percentage of SVs in men with <15% risk of SV involvement, suggesting that there may be over-treatment of SVs that increases the risk of rectal or bladder toxicity.

Magnetic resonance imaging-guided radiotherapy for intermediate- and high-risk prostate cancer: Trade-off between planning target volume margin and online plan adaption

Magnetic resonance-guided radiotherapy with daily plan adaptation for intermediate- and high-risk prostate cancer is time and labor intensive. Fifty adapted plans with 3 mm planning target volume (PTV)-margin were compared with non-adapted plans using 3 or 5 mm margins. Adequate (V95% ≥ 95%) prostate coverage was achieved in 49 fractions with 5 mm PTV without plan adaptation, however, coverage of the seminal vesicles (SV) was insufficient in 15 of 50 fractions. There was no insufficient coverage for prostate and SV using plan adaptation with 3 mm. Hence, daily adaptation is recommended to obtain adequate SV-coverage when using 3 mm PTV.

Proximal seminal vesicle displacement and margins for prostate cancer radiotherapy

INTRODUCTION

Guidelines recommend that the proximal seminal vesicles (PrSV) should be included in the clinical target volume for locally advanced prostate cancer patients undergoing radiotherapy. Verification and margins for the prostate may not necessarily account for PrSV displacement. The purpose was to determine the inter-fraction displacement of the PrSV relative to the prostate during radiotherapy.

METHODS

Fiducials were inserted into the prostate, and right and left PrSV (RSV and LSV) in 30 prostate cancer patients. Correctional shifts for the prostate, right and left PrSV and pelvic bones were determined from each patient's 39 daily orthogonal portal images relative to reference digitally reconstructed radiographs.

RESULTS

There was a significant displacement of the RSV relative to the prostate in all directions: on average 0.38 mm (95% confidence interval (CI) 0.26 to 0.50) to the left, 0.80-0.81 mm (CI 0.68 to 0.93) superiorly and 1.51 mm (CI 1.36 to 1.65) posteriorly. The LSV was significantly displaced superiorly to the prostate 1.09-1.13 mm (CI 0.97 to 1.25) and posteriorly 1.81 mm (CI 1.67 to 1.96), but not laterally (mean 0.06, CI -0.06 to 0.18). The calculated PTV margins (left-right, superior-inferior, posterior-anterior) were 4.9, 5.3-5.6 and 4.8 mm for the prostate, 5.2, 7.1-8.0 and 9.7 mm for the RSV, and 7.2, 7.5-7.6 and 8.6 mm for the LSV.

CONCLUSION

There is a significant displacement of the PrSV relative to the prostate during radiotherapy. Greater margins are recommended for the PrSV compared to the prostate.

Patterns of care for prostate cancer radiotherapy-results from a survey among German-speaking radiation oncologists

Background

Emerging moderately hypofractionated and ultra-hypofractionated schemes for radiotherapy (RT) of prostate cancer (PC) have resulted in various treatment options. The aim of this survey was to evaluate recent patterns of care of German-speaking radiation oncologists for RT of PC.

Methods

We developed an online survey which we distributed via e‑mail to all registered members of the German Society of Radiation Oncology (DEGRO). The survey was completed by 109 participants between March 3 and April 3, 2020. For evaluation of radiation dose, we used the equivalent dose at fractionation of 2 Gy with α/β = 1.5 Gy, equivalent dose (EQD2 [1.5 Gy]).

Results

Median EQD2(1.5 Gy) for definitive RT of the prostate is 77.60 Gy (range: 64.49–84.00) with median single doses (SD) of 2.00 Gy (range: 1.80–3.00), while for postoperative RT of the prostate bed, median EQD2(1.5 Gy) is 66.00 Gy (range: 60.00–74.00) with median SD of 2.00 Gy (range: 1.80–2.00). For definitive RT, the pelvic lymph nodes (LNs) are treated in case of suspect findings in imaging (82.6%) and/or according to risk formulas/tables (78.0%). In the postoperative setting, 78.9% use imaging and 78.0% use the postoperative tumor stage for LN irradiation. In the definitive and postoperative situation, LNs are irradiated with a median EQD2(1.5 Gy) of 47.52 Gy with a range of 42.43–66.00 and 41.76–62.79, respectively.

Conclusion

German-speaking radiation oncologists’ patterns of care for patients with PC are mainly in line with the published data and treatment recommendation guidelines. However, dose prescription is highly heterogenous for RT of the prostate/prostate bed, while the dose to the pelvic LNs is mainly consistent.

Supplementary Information

The online version of this article (10.1007/s00066-020-01738-1) contains supplementary material, which is available to authorized users.

The Horse is at the Stable Door: Management of N1M0 Prostate Cancer

Pelvic lymph node involvement in prostate cancer is a significant poor prognostic factor with very little evidence on the optimal management options for these patients. It is estimated that lymph node-positive patients make up 12% of newly diagnosed prostate cancer and this figure is expected to rise with the advancement and increasing use of novel imaging. The controversy around this subgroup of patients is whether this is an intermediary stage before disseminated disease and hence amenable to curative treatment options. Systemic therapies have been the mainstay of treatment for these patients for decades, but in recent years, studies have emerged supporting the addition of local therapy. This review will focus on the current multimodal management approach for clinical and pathological lymph node-positive prostate cancer with a focus on radiotherapy options and aims to provide the rationale for a curative approach with a combination of local and systemic therapy.

ESTRO ACROP consensus guideline on CT- and MRI-based target volume delineation for primary radiation therapy of localized prostate cancer

BACKGROUND AND PURPOSE

Delineation of clinical target volumes (CTVs) remains a weak link in radiation therapy (RT), and large inter-observer variation is seen. Guidelines for target and organs at risk delineation for prostate cancer in the primary setting are scarce. The aim was to develop a delineation guideline obtained by consensus between a broad European group of radiation oncologists.

MATERIAL AND METHODS

An ESTRO contouring consensus panel consisting of leading radiation oncologists and one radiologist with known subspecialty expertise in prostate cancer was asked to delineate the prostate, seminal vesicles and rectum on co-registered CT and MRI scans. After evaluation of the different contours, literature review and multiple informal discussions by electronic mail a CTV definition was defined and a guide for contouring the CTV of the prostate and the rectum was developed.

RESULTS

The panel achieved consensus CTV contouring definitions to be used as guideline for primary RT of localized prostate cancer.

CONCLUSION

The ESTRO consensus on CT/MRI based CTV delineation for primary RT of localized prostate cancer, endorsed by a broad base of the radiation oncology community, is presented to improve consistency and reliability.

How Histopathologic Tumor Extent and Patterns of Recurrence Data Inform the Development of Radiation Therapy Treatment Volumes in Solid Malignancies

The ability to deliver highly conformal radiation therapy using intensity-modulated radiation therapy and particle therapy provides for new opportunities to improve patient outcomes by reducing treatment-related morbidities following radiation therapy. By reducing the volume of normal tissue exposed to radiation therapy (RT), while also allowing for the opportunity to escalate the dose of RT delivered to the tumor, use of conformal RT delivery should also provide the possibility of expanding the therapeutic index of radiotherapy. However, the ability to safely and confidently deliver conformal RT is largely dependent on our ability to clearly define the clinical target volume for radiation therapy, which requires an in-depth knowledge of histopathologic extent of different tumor types, as well as patterns of recurrence data. In this article, we provide a comprehensive review of the histopathologic and radiographic data that provide the basis for evidence-based guidelines for clinical tumor volume delineation.

The longitudinal effect of ejaculation on seminal vesicle fluid volume and whole-prostate ADC as measured on prostate MRI

OBJECTIVE

To prospectively investigate the longitudinal effect of ejaculatory abstinence on MRI-measured seminal vesicle (SV) volume and whole-prostate ADC over consecutive days.

METHODS

15 healthy male volunteers (mean 35.9 years, range 27-53) underwent 3-T MRI at baseline and 1, 2 and 3 days post-ejaculation. Prostate and SV volumes were derived by volume segmentation and whole-gland apparent diffusion coefficient (ADC) values calculated. A mixed-effects linear regression compared ADC values and prostate/seminal vesicle volumes in each volunteer between studies in a pairwise manner.

RESULTS

All subjects completed the four MRIs. Mean prostate volume was 22.45 cm3 (range 13.04-31.21 cm3), with no change between the four studies (p = 0.89-0.99). 13/15 subjects showed SV volume reduction from baseline to day 1, with group-mean decreasing from 6.45 to 4.80 cm3 (-25.6%, p < 0.001), and a significant reduction from baseline to day 2 (-18.1%, p = 0.002). There was a significant volume increase from both day 1 (+21.3%, p = 0.006) and day 2 (+10.2%, p = 0.022) to day 3 post-ejaculation. There was a significant reduction in ADC from 1.105 at baseline to 1.056 × 10-3 mm2/s at day 1 (mean -4.3%, p = 0.009).

CONCLUSION

The longitudinal effect of ejaculation on SV volume was demonstrated. Significant reductions in SV volume and whole-gland ADC were observed post-ejaculation, supporting a 3-day period of abstinence before prostate MRI.

KEY POINTS

• Seminal vesicle volume significantly reduced 24 h post-ejaculation remaining reduced at day 2 • Seminal vesicle fluid volume significantly increased from day 1 to day 3 post-ejaculation • There was a significant reduction in whole-gland prostate ADC values day 1 post-ejaculation • 3-day abstinence from ejaculation is required to ensure maximal seminal vesicle distension.

The association between seminal vesicle size and duration of abstinence from ejaculation

There are few data describing the relationship between seminal vesicle (SV) size and duration of abstinence between ejaculations. This study evaluates the association between SV size and duration of abstinence from ejaculation using pelvic magnetic resonance imaging (MRI). Sexually active men 18-68 years old who underwent pelvic MRI for various medical indications were included. The date of last ejaculation was recorded, and the cross-sectional areas of the right and left seminal vesicles were calculated separately using mediolateral and anteroposterior measurements on T2-weighted MRI images. The association between SV area and duration of abstinence between ejaculations was determined via linear regression analysis. The study cohort consisted of 104 men with a mean age of 46.45 ± 11.4 (range 18-68) years old. Mean right and left SV cross-sectional areas were 744.1 ± 351.1 (range: 149.9-1794.7) mm² and 727.6 ± 359.2 (range 171.4-2248.4) mm² respectively. The mean duration of abstinence between ejaculations in the cohort was 3.6 ± 2.6 (range 1-15) days. Although no correlation between age and SV area was observed (r = .007, p = .947), linear regression analysis demonstrated a positive correlation between SV area and the duration of abstinence from ejaculation (r = .372, p = .0001). SV cross-sectional area increases with duration of abstinence from ejaculation and can be assessed using MRI. The use of SV size estimation may be applicable in diagnosis, risk stratification and treatment of urological diseases.

Do androgen deprivation and the biologically equivalent dose matter in low-dose-rate brachytherapy for intermediate-risk prostate cancer?

The objective of this study was to investigate the impact of the biologically equivalent dose (BED) on treatment outcomes after iodine‐125 low‐dose‐rate brachytherapy (LDR‐BT) with or without supplemental external beam radiotherapy (EBRT) and androgen deprivation therapy (ADT) for intermediate‐risk prostate cancer (PCa). We retrospectively evaluated 292 Japanese patients. The impact of the BED and ADT on treatment outcomes was investigated. Cox proportional hazard models were used for univariate and multivariate analysis with biological progression‐free survival (bPFS) and clinical progression‐free survival (cPFS) as the primary outcome measures. The median follow‐up was 66 months. The bPFS and cPFS rates at 5‐/7‐years were 91.6/87.7% and 95.9/94.0%, respectively. When stratified by BED levels, the bPFS rates at 5‐/7‐years were 92.1/89.3% for <178.0 Gy_2, and 91.2/86.0% for ≥178.0 Gy₂, respectively (P > 0.05). Based on ADT duration, the bPFS rates at 5‐/7‐years were 89.8/83.5%, 89.7/89.7%, and 97.5/97.5% for none, 1–3 months, and 4–12 months, respectively (P = 0.03). For the univariate analysis, the use of ADT and its duration were significant predictors for bPFS, whereas BED was not significant. A multivariate analysis did not indicate the use of ADT itself was significant, however, when covariates were accounted for by the duration of ADT, the longer use of ADT was found to significantly improve bPFS. Although cPFS was associated neither with the BED levels nor ADT duration (P > 0.05), ADT duration had a trend of improving cPFS (P = 0.053). The higher levels of BED did not significantly impact bPFS for intermediate‐risk PCa after LDR‐BT with or without supplemental EBRT and ADT. The longer duration of ADT could provide an additional benefit in the context of high‐dose irradiation generated by LDR‐BT.