Apports de la radiothérapie avec modulation d’intensité guidée par l’image dans les cancers prostatiques

Sexual Structure Sparing for Prostate Cancer Radiotherapy: A Systematic Review

CONTEXT

Erectile dysfunction represents a major side effect of prostate cancer (PCa) treatment, negatively impacting men's quality of life. While radiation therapy (RT) advances have enabled the mitigation of both genitourinary and gastrointestinal toxicities, no significant improvement has been showed in sexual quality of life over time.

OBJECTIVE

The primary aim of this review was to assess sexual structures' dose-volume parameters associated with the onset of erectile dysfunction.

EVIDENCE ACQUISITION

We searched the PubMed database and ClinicalTrials.gov until January 4, 2023. Studies reporting the impact of the dose delivered to sexual structures on sexual function or the feasibility of innovative sexual structure-sparing approaches were deemed eligible.

EVIDENCE SYNTHESIS

Sexual-sparing strategies have involved four sexual organs. The mean penile bulb doses exceeding 20 Gy are predictive of erectile dysfunction in modern PCa RT trial. Maintaining a D100% of ≤36 Gy on the internal pudendal arteries showed preservation of erectile function in 88% of patients at 5 yr. Neurovascular bundle sparing appears feasible with magnetic resonance-guided radiation therapy, yet its clinical impact remains unanswered. Doses delivered to the testicles during PCa RT usually remain <2 Gy and generate a decrease in testosterone levels ranging from -4.6% to -17%, unlikely to have any clinical impact.

CONCLUSIONS

Current data highlight the technical feasibility of sexual sparing for PCa RT. The proportion of erectile dysfunction attributable to the dose delivered to sexual structures is still largely unknown. While the ability to maintain sexual function over time is impacted by factors such as age or comorbidities, only selected patients are likely to benefit from sexual-sparing RT.

PATIENT SUMMARY

Technical advances in radiation therapy (RT) made it possible to significantly lower the dose delivered to sexual structures. While sexual function is known to decline with age, the preservation of sexual structures for prostate cancer RT is likely to be beneficial only in selected patients.

State of the art and future challenges of urethra-sparing stereotactic body radiotherapy for prostate cancer: a systematic review of literature

PURPOSE

Doses delivered to the urethra have been associated with an increased risk to develop long-term urinary toxicity in patients undergoing stereotactic body radiotherapy (SBRT) for prostate cancer (PCa). Aim of the present systematic review is to report on the role of urethra-sparing SBRT (US-SBRT) techniques for prostate cancer, with a focus on outcome and urinary toxicity.

METHOD

A systematic review of the literature was performed on the PubMed database on May 2023. Based on the urethra-sparing technique, 13 studies were selected for the analysis and classified in the two following categories: "urethra-steering" SBRT (restriction of hotspots to the urethra) and "urethra dose-reduction" SBRT (dose reduction to urethra below the prescribed dose).

RESULTS

By limiting the urethra Dmax to 90GyEQD2 (α/β = 3 Gy) with urethra-steering SBRT techniques, late genitourinary (GU) grade 2 toxicity remains mild, ranging between 12.1% and 14%. With dose-reduction strategies decreasing the urethral dose below 70 GyEQD2, the risk of late GU toxicity was further reduced (< 8% at 5 years), while maintaining biochemical relapse-free survival rates up to 93% at 5 years.

CONCLUSION

US-SBRT techniques limiting maximum doses to urethra below a 90GyEQD2 (α/β = 3 Gy) threshold result in a low rate of acute and late grade ≥ 2 GU toxicity. A better understanding of clinical factors and anatomical substructures involved in the development of GU toxicity, as well as the development and use of adapted dose constraints, is expected to further reduce the long-term GU toxicity of prostate cancer patients treated with SBRT.

CBCT evaluation of inter- and intra-fraction motions during prostate stereotactic body radiotherapy: a technical note

Background

In most clinical trials, gold fiducial markers are implanted in the prostate to tune the table position before each radiation beam. Yet, it is unclear if a cone-beam computed tomography (CBCT) should be performed before each beam to monitor a possible variation of the organs at risk (OARs) fullness, especially in case of recto-prostatic spacer implantation. The present study aimed at assessing the inter- and intra-fraction movements of prostate, bladder and rectum in patients implanted with a hyaluronic acid spacer and undergoing prostate stereotactic body radiotherapy (SBRT).

Methods

Data about consecutive patients undergoing prostate SBRT were prospectively collected between 2015 and 2019. Inter-and intra-fraction prostate displacements and volume variation of organs at risk (OARs) were assessed with CBCTs.

Results

Eight patients were included. They underwent prostate SBRT (37.5Gy, 5 fractions of 7.5Gy) guided by prostate gold fiducial markers. Inter-fraction variation of the bladder volume was insignificant. Intra-fraction mean increase of the bladder volume was modest (29 cc) but significant (p < 0.001). Both inter- and intra-fraction variations of the rectum volume were insignificant but for one patient. He had no rectal toxicity. The magnitude of table displacement necessary to match the prostate gold fiducial marker frequently exceeded the CTV/PTV margins (0.4 cm) before the first (35%) and the second arc (15%). Inter- and intra-fraction bladder and rectum volume variations did not correlate with prostate displacement.

Conclusion

Major prostate position variations were reported. In-room kV fiducial imaging before each arc seems mandatory. Intra-fraction imaging of the OARs appears unnecessary. We suggest that only one CBCT is needed before the first arc.

Trial registration

NCT02361515, February 11th, 2015.

[Indications and outlooks of radiohormonal therapy of high-risk prostate cancers]

Prostate cancer is a sensitive adenocarcinoma, in more than 80% of cases, to chemical castration, due to its hormone dependence. Locally advanced and/or high-risk cancer is defined based on clinical stage, initial prostate specific antigen serum concentration value or high Gleason score. Hormone therapy associated with radiation therapy is the standard of management and improves local control, reduces the risk of distant metastasis and improves specific and overall survival. Duration of hormone therapy, dose level of radiation therapy alone or associated with brachytherapy are controversial data in the literature. The therapeutic choice, multidisciplinary, depends on the age and comorbidity of the patient, the prognostic criteria of the pathology and the urinary function of the patient. Current research focuses on optimizing local and distant control of these aggressive forms and incorporates neoadjuvant or adjuvant chemotherapy and also new hormone therapies.

Proton versus photon-based radiation therapy for prostate cancer: emerging evidence and considerations in the era of value-based cancer care

BACKGROUND

Advances in radiation technology have transformed treatment options for patients with localized prostate cancer. The evolution of three-dimensional conformal radiation therapy and intensity-modulated radiation therapy (IMRT) have allowed physicians to spare surrounding normal organs and reduce adverse effects. The introduction of proton beam technology and its physical advantage of depositing its energy in tissue at the end-of-range maximum may potentially spare critical organs such as the bladder and rectum in prostate cancer patients. Data thus far are limited to large, observational studies that have not yet demonstrated a definite benefit of protons over conventional treatment with IMRT. The cost of proton beam treatment adds to the controversy within the field.

METHODS

We performed an extensive literature review for all proton treatment-related prostate cancer studies. We discuss the history of proton beam technology, as well as its role in the treatment of prostate cancer, associated controversies, novel technology trends, a discussion of cost-effectiveness, and an overview of the ongoing modern large prospective studies that aim to resolve the debate between protons and photons for prostate cancer.

RESULTS

Present data have demonstrated that proton beam therapy is safe and effective compared with the standard treatment options for prostate cancer. While dosimetric studies suggest lower whole-body radiation dose and a theoretically higher relative biological effectiveness in prostate cancer compared with photons, no studies have demonstrated a clear benefit with protons.

CONCLUSIONS

Evolving trends in proton treatment delivery and proton center business models are helping to reduce costs. Introduction of existing technology into proton delivery allows further control of organ motion and addressing organs-at-risk. Finally, the much-awaited contemporary studies comparing photon with proton-based treatments, with primary endpoints of patient-reported quality-of-life, will help us understand the differences between proton and photon-based treatments for prostate cancer in the modern era.

Current Progress and Controversies in Prostate Cancer Management

Objective:

The optimal management strategy for prostate cancer (PCa) remains controversial. We performed a systemic review of current progress and controversies regarding the diagnosis and treatment of PCa.

Data Sources:

We searched PubMed for recently published articles up to July 2017 using the following key words: “prostate cancer,” “progress,” “controversy,” “immunotherapy,” and “prevention.”

Study Selection:

Articles were obtained and reviewed to provide a systematic review of the current progress and controversies regarding PCa management.

Results:

The value of serum prostate-specific antigen (PSA) screening remains controversial, but PSA screening is recommended to facilitate the early diagnosis of PCa in high-risk groups. Prostate biopsy via the transrectal or perineal approach has both advantages and disadvantages. There was a significant correlation between testosterone levels and PCa prognosis. The current research is focused on the mechanisms responsible for PCa. Active surveillance has been proposed as a management strategy for low-risk, localized PCa, but there is an urgent need for further clinical studies to establish the criteria for recommending this approach. The main complications of radical resection for PCa are urinary incontinence and erectile dysfunction, though three-dimensional laparoscopic and robot-assisted laparoscopic techniques have obvious advantages over radical surgery. Radiotherapy is also a therapeutic option for PCa, while immunotherapies may alter the prostate tumor microenvironment. Ongoing studies aim to provide guidance on effective sequential and combination strategies. Prevention remains an important strategy for reducing PCa morbidity and mortality.

Conclusions:

The diagnosis, treatment, and prevention of PCa are complex issues, worthy of intensive study. Further studies are needed to improve the management of PCa.

Changes in penile bulb dose when using the Clarity transperineal ultrasound probe: A planning study

PURPOSE

The Clarity system allows monitoring of intrafraction target organ movements in external beam radiation therapy of prostate cancer by using transperineal ultrasound. The probe positioning at the perineum could lead to a compression and shift of the penile bulb (PB) toward the high-dose region. Dose to the PB has been reported to be associated with the risk of posttreatment erectile dysfunction. This planning study reports on PB translations and changes in volume and dose when applying the transperineal ultrasound probe.

METHODS AND MATERIALS

For 10 patients treated with external beam radiation therapy for prostate cancer between 2013 and 2014, a planning computed tomography scan with and without the ultrasound probe in place was acquired. The planning target volume and organs at risk including the PB were contoured in the computed tomography scan with and without the probe. Radiation therapy plans for both scenarios were calculated. In a second step, for planning with the probe in position, an additional objective for improved sparing of the PB was introduced.

RESULTS

The median PB volume was 5.5 mL (range, 3.8-7.1 mL) without the probe and 3.5 mL (range, 2.0-5.8 mL) with the probe. The median shift of the PB was 1 mm in the posterior (range, 3 mm posterior-2 mm anterior) and 6 mm in the superior direction (range, 0-14 mm superior), with no relevant shift of the prostate. The median mean dose in 95% of the PB was 34.1 Gy (range, 6.0-50.4 Gy), 48.3 Gy (range, 7.2-56.8 Gy), and 39.4 Gy (range, 5.6-51.3 Gy) for plans without probe, with probe, and with probe and additional planning objective, respectively.

CONCLUSIONS

Dose to the PB increased when using the transperineal probe. After introducing an additional plan-optimization objective for PB sparing, dose-volume parameters were below Quantitative Analyses of Normal Tissue Effects in the Clinic thresholds for all but one patient.

No increase in toxicity of pelvic irradiation when intensity modulation is employed: clinical and dosimetric data of 208 patients treated with post-prostatectomy radiotherapy

OBJECTIVE

To compare the toxicity of image-guided intensity-modulated radiotherapy (IG-IMRT) to the pelvis or prostate bed (PB) only. To test the hypothesis that the potentially injurious effect of pelvic irradiation can be counterbalanced by reduced irradiated normal tissue volume using IG-IMRT.

METHODS

Between February 2010 and February 2012, 208 patients with prostate cancer were treated with adjuvant or salvage IG-IMRT to the PB (102 patients, Group PB) or the pelvis and prostate bed (P) (106 patients, Group P). The Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer criteria were used to evaluate toxicity.

RESULTS

Median follow-up was 27 months. Toxicity G ≥ 2 in Group PB: in the bowel acute and late toxicities were 11.8% and 10%, respectively; urinary acute and late toxicities were 10.8% and 15%, respectively. Toxicity G ≥ 2 in Group P: in the bowel acute and late toxicities were both 13.2%; urinary acute and late toxicities were 13.2% and 15.1%, respectively. No statistical difference in acute or late toxicity between the groups was found (bowel: p = 0.23 and p = 0.89 for acute and late toxicity, respectively; urinary: p = 0.39 and p = 0.66 for acute and late toxicity, respectively). Of the clinical variables, only previous abdominal surgery was correlated with acute bowel toxicity. Dosimetric parameters that correlated with bowel toxicity were identified.

CONCLUSION

The toxicity rates were low and similar in both groups, suggesting that IG-IMRT allows for a safe post-operative irradiation of larger volumes. Further investigation is warranted to exclude bias owing to non-randomized character of the study.

ADVANCES IN KNOWLEDGE

Our report shows that modern radiotherapy technology and careful planning allow maintaining the toxicity of pelvic lymph node treatment at the acceptable level, as it is in the case of PB radiotherapy.

[Localized prostate cancer: Radiotherapeutic concepts]

BACKGROUND

Radiation therapy is an established cornerstone in the treatment of prostate cancer. Significant advances in the techniques and therapeutic concepts have been made in recent decades.

OBJECTIVES

The objective of this article is to provide an overview of current standards of care and recent technical and conceptional developments.

CONCLUSIONS

Three-dimensional conformal radiotherapy has long been the standard of care for percutaneous radiotherapy. The development of intensity-modulated radiation therapy (IMRT) and image-guided radiation therapy (IGRT) have increased the precision of treatment, thus, reducing side effects and allowing dose escalation. LDR (low dose rate) and HDR (high dose rate) brachytherapy alone or in combination are a treatment option in localized prostate cancer with a distinct side effect profile. The roles of proton therapy and stereotactic radiotherapy should be further investigated in prospective trials.

[Comparative oncologic and functional outcomes of prostate cancer surgery with other curative treatments]

OBJECTIVE

Review of the comparative results of different treatment strategies (surgery, radiotherapy, ultrasound, surveillance) of prostate cancer, in which the main goal is the local control and the second target is the tolerance of the side effects of those treatments.

MATERIALS AND METHODS

Review of literature using Medline databases selected based on scientific relevance. Clinical keys centered on the oncological and functional outcomes of comparative series between different curative treatments.

RESULTS

The numerous comparative series between surgery and other therapeutic modalities are essentially retrospective with significant methodological bias that is difficult to overcome in order to formulate the optimal thesis. However, there is a clear tendency toward surgery usually with young patients who have intermediate risk tumors without important comorbidity.

CONCLUSION

In the absence of randomized comparative series with significant power, the oncological and functional results of the radical prostatectomy with or without adjuvant treatment seem at least the same, in a selected population of patients, compared with the combination of radiotherapy-hormonotherapy in terms of survival, without biochemical recurrence, disease-specific survival and overall survival, for the aggressive tumors necessitating curative local treatments.

[What is the level of evidence of new techniques in prostate cancer radiotherapy?]

Prostate cancer radiotherapy has evolved from the old 2D technique to conformal, and then to intensity-modulated radiation therapy (IMRT) and stereotactic radiotherapy. At the same time, image-guidance (IGRT) is routinely used. New techniques such as protontherapy or carbontherapy are being developed with the objective of increased efficacy, decreased treatment duration, toxicity or cost. This review summarizes the evidence-based medicine of new technologies in the treatment of prostate cancer.

Dosimetric evaluation of intensity modulated radiotherapy and 4-field 3-d conformal radiotherapy in prostate cancer treatment

OBJECTIVE

The purpose of this dosimetric study is the targeted dose homogeneity and critical organ dose comparison of 7-field Intensity Modulated Radiotherapy (IMRT) and 3-D 4-field conformal radiotherapy.

STUDY DESIGN

Cross sectional study.

MATERIAL AND METHODS

Twenty patients with low and moderate risk prostate cancer treated at Gülhane Military Medical School Radiation Oncology Department between January 2009 and December 2009 are included in this study. Two seperate dosimetric plans both for 7-field IMRT and 3D-CRT have been generated for each patient to comparatively evaluate the dosimetric status of both techniques and all the patients received 7-field IMRT.

RESULTS

Dose-comparative evaluation of two techniques revealed the superiority of IMRT technique with statistically significantly lower femoral head doses along with reduced critical organ dose-volume parameters of bladder V60 (the volume receiving 60 Gy) and rectal V40 (the volume receiving 40 Gy) and V60.

CONCLUSION

It can be concluded that IMRT is an effective definitive management tool for prostate cancer with improved critical organ sparing and excellent dose homogenization in target organs of prostate and seminal vesicles.

Setup margins and geometric uncertainties in intensity-modulated radiation therapy in treating pituitary adenomas: the experience of Lyon Sud Hospital

PURPOSE

The authors retrospectively evaluated the setup uncertainties in Intensity-Modulated Radiation Therapy (IMRT) for pituitary adenomas and verified the margins used in daily practice (3 mm).

MATERIALS AND METHODS

Craniocaudal (CC), anteroposterior (AP) and laterolateral (LL) displacements were measured during the first 3 days of treatment and then weekly by comparing two orthogonal images obtained by an electronic system of portal imaging with Digitally Reconstructed Radiographs (DRRs). Setup Margins (SM) were defined according to the International Commission on Radiation Units (ICRU)-62 formula, the Stroom equation and the van Herk equation. The systematic (Σ) and random (σ) errors of the population were calculated as standard deviation (SD) of the population mean and the mean of SDs for every patient, respectively.

RESULTS

Twenty patients were treated by IMRT for pituitary adenomas, and a total of 231 measurements were obtained. Σ and σ were 0.6 and 1.3 mm, 0.8 and 1 mm, 1.2 and 1.5 mm in the AP, LL and CC direction, respectively. Larger setup margin was 2.4, 2.7 and 4 mm in the AP, LL and CC direction, respectively (van Herk formula).

CONCLUSIONS

IMRT is a highly sophisticated treatment technique that requires precise definition and optimisation of local setup errors and, finally, of the irradiated volumes. The role of image-guided RT in these kinds of treatments should be prospectively evaluated.

Image-guided radiotherapy: has it influenced patient outcomes?

Cancer control and toxicity outcomes are the mainstay of evidence-based medicine in radiation oncology. However, radiotherapy is an intricate therapy involving numerous processes that need to be executed appropriately in order for the therapy to be delivered successfully. The use of image-guided radiation therapy (IGRT), referring to imaging occurring in the radiation therapy room with per-patient adjustments, can increase the agreement between the planned and the actual dose delivered. However, the absence of direct evidence regarding the clinical benefit of IGRT has been a criticism. Here, we dissect the role of IGRT in the radiotherapy (RT) process and emphasize its role in improving the quality of the intervention. The literature is reviewed to collect evidence that supports that higher-quality dose delivery enabled by IGRT results in higher clinical control rates, reduced toxicity, and new treatment options for patients that previously were without viable options.

Active surveillance vs. treatment for low-risk prostate cancer: a cost comparison

OBJECTIVE

Radical prostatectomy (RP) and radiation therapy are standard curative approaches for low-risk prostate cancer (PC). Active surveillance (AS) is becoming an increasingly accepted management alternative for low-risk PC. Our aim is to compare the cumulative medical costs of treatment vs. AS.

METHODS AND MATERIALS

We collected data on the cumulative medical costs of open radical retropubic prostatectomy (RRP), robotic-assisted radical prostatectomy (RARP), external beam radiotherapy (EBRT), brachytherapy (BT), and AS at our institution. For physicians' reimbursements, Medicare values of our region were used to maintain uniformity. For inpatient costs other than reimbursements, we used the mean cost at our institution. The costs of RRP and RARP involve preoperative investigations, medical clearance, physicians' fees, inpatient costs, and pathologic examination of prostatectomy specimen and follow-up. The inpatient costs include the operating room, disposable equipment, anesthesia, post-anesthesia care, transfusion, and hospital stay. The cost of EBRT involves the cost of consultation, planning, simulation and treatment sessions, and follow-up. BT costs involved radiotherapy planning as well as inpatients costs. AS protocol involves regular visits, transrectal ultrasound guided biopsies, prostate specific antigen (PSA) testing. To evaluate the cost of treating complications, treatment after AS, and treatment for recurrence, we created a Markov model based on recent studies and our experience.

RESULTS

The cumulative costs of RRP are $9,732 (1 year), $10,360 (2 years), $12,209 (5 years), and $15,084 (10 years). While for RARP, the costs are $17,824 (1 year), $18,308 (2 years), $20,117 (5 years), and $22,762 (10 years). The costs of EBRT are $20,730 (1 year), $20,969 (2 years), $22,043 (5 years), and $23,953 (10 years). BT costs are $14,061 (1 year), $14,300 (2 years), $15,374 (5 years), and $17,284 (10 years). The costs of AS are $1,154 (1 year), $2,308 (2 years), $8,761 (5 years), and $13,116 (10 years).

CONCLUSIONS

The cumulative medical costs of RARP and EBRT are much higher than BT, RRP, and AS. AS is associated with a different cost distribution in which the initial cost is low and relatively higher cost of follow-up. Despite the higher follow-up cost, AS remains the most cost effective alternative for low-risk PC.

[SFRO 2010: congress highlights]

The 21st SFRO Congress during October 2010 focused on three main topics: prostate, radiotherapy technical innovations (including reirradiation) and quality of life. The pitfalls of IMRT (treatment time, number of monitor unit, low doses) are in competition with arctherapy dynamic techniques that offer reduction treatment time for an equivalent ballistic. These techniques with high dose gradient should be coupled with the better imagery of repositioning (IGRT) to ensure benefice. A prospective evaluation of toxicity, clinical benefit on tumor control but also on quality of life of patients is necessary. In many current and future clinical trials, quality of life related to health will be a relevant outcome measurement to secure the importance of treatment for the patient and the health system.