Radiation-induced erectile dysfunction: Recent advances and future directions

Comparing the efficacy of tadalafil and tamsulosin for managing erectile dysfunction and lower urinary tract symptoms in prostate brachytherapy patients: a prospective study

Introduction

Adverse events, such as erectile dysfunction (ED) and lower urinary tract symptoms (LUTS), are significant concerns in prostate cancer (PCa) patients treated with Iodine 125 (I-125) low-dose rate (LDR) prostate brachytherapy (PB). Alpha antagonists and phosphodiesterase-5 inhibitors are used to manage these events. The present study compared the efficacy of low-dose tadalafil with that of tamsulosin for concomitant ED and LUTS in PCa patients treated with I-125 LDR PB.

Materials and methods

One hundred and seventeen patients who received PB for low- or intermediate-risk localized PCa were analyzed. They were randomized into two groups, one receiving tamsulosin (N = 58) and the other receiving low-dose tadalafil (N = 59) immediately after PB. Sexual and urinary functions were assessed at various time points post-PB using questionnaires and objective measurements. The primary endpoint was sexual function measured by the International Index of Erectile Function-15 (IIEF-15) EF domain scores 6 months after PB. Secondary endpoints were sexual function measured by total IIEF-15 scores and Erection Hardness Scores 6 months after PB. The exploratory endpoint was the LUTS status 6 months after PB.

Results

No significant differences were observed in baseline characteristics between the two groups. Tadalafil exerted stronger effects on sexual function, particularly erection hardness, than tamsulosin. No significant differences were observed in the management of LUTS between both treatments.

Conclusion

Low-dose tadalafil and tamsulosin may manage LUTS equally after PB. Low-dose tadalafil may contribute to the maintenance of erectile function, particularly erection hardness, after PB; therefore, it is a viable option for patients with baseline erectile function.

Treatment outcome of localized prostate cancer using transperineal ultrasound image-guided radiotherapy

BACKGROUND

We report the results of a retrospective analysis of localized prostate cancer (LPCa) treated with transperineal ultrasound image-guided radiotherapy (TPUS-IGRT).

METHODS

A total of 124 patients (median age: 74 y, 46-84 y) with LPCa who underwent TPUS-IGRT (Clarity Autoscan system; CAS, Elekta; Stockholm, Sweden) between April 2016 and October 2021 for curative/after hormone induction were enrolled. The number of patients by risk (National Comprehensive Cancer Network 2019) was 7, 25, 42, and 50 for low (LR), good intermediate (good IR), poor intermediate (poor IR), and high (HR)/very high (VHR), respectively. Ninety-five patients were given neoadjuvant hormonal therapy. The planning target volume margin setting was 3 mm for rectal in most cases, 5-7 mm for superior/inferior, and 5 mm for anterior/right/left. The principle prescribed dose is 74 Gy (LR), 76 Gy (good IR), and 76-78 Gy (poor IR or above). CAS was equipped with a real-time prostate intrafraction monitoring (RTPIFM) system. When a displacement of 2-3 mm or more was detected, irradiation was paused, and the patients were placed on standby for prostate reinstatement/recorrection. Of the 3135 fractions in 85 patients for whom RTPIFM was performed, 1008 fractions (32.1%) were recorrected at least once after starting irradiation.

RESULTS

A total of 123 patients completed the radiotherapy course. The 5-year overall survival rate was 95.9%. The 5-year biological prostate-specific antigen relapse-free survival rate (bPFS) was 100% for LR, 92.9% for intermediate IR, and 93.2% for HR/VHR (Phoenix method). The 5-year late toxicity rate of Grade 2+ was 7.4% for genitourinary (GU) and 6.5% for gastrointestinal (GI) organs. Comparing the ≤ 76 Gy group to the 78 Gy group for both GU and GI organs, the incidence was higher in the 78 Gy group for both groups.

CONCLUSION

These results suggest that TPUS-IGRT is well tolerated, as the bPFS and incidence of late toxicity are almost comparable to those reported by other sources of image-guided radiotherapy.

[Relationship between doses to anatomical structures and erectile dysfunction after radiotherapy for prostate cancer: A systematic review]

PURPOSE

During prostatic radiotherapy, damage to several anatomical structures could be the cause of erectile dysfunction: corpora cavernosa, internal pudendal arteries, penile bulb, and neurovascular bundles. Numerous studies have analysed the correlations between the dose received by these structures and erectile function. The objective of this article is to make a systematic review on current knowledge.

MATERIALS AND METHODS

A systematic review was performed in the Medline database using the search engine PubMed. Keywords for the search included: erectile dysfunction, penile bulb, corpora cavernosa, cavernosum, neurovascular bundles, radiation therapy, cancer, prostate cancer. The selected articles must study a correlation between erectile dysfunction and the dose received by anatomical structures. A total of 152 articles were identified. Of these 152 articles, 45 fulfilled the defined selection criteria.

RESULTS

For corpora cavernosa, seven studies were identified, only two studies demonstrated a significant correlation between the dose received by corpora cavernosa and the occurrence of erectile dysfunction. For penile bulb, only 15 of 23 studies showed a correlation. A mean dose on the penile bulb greater than 20Gy was found to be predictive of erectile dysfunction. None of the eight trials concerning neurovascular bundles succeeded to show a correlation between dose and erectile dysfunction. Only one study evaluated the relationship between the dose received by internal pudendal arteries and erectile dysfunction but was found to be negative. However, vessels-sparing studies showed good results on erectile function preservation without compromising the target volume.

CONCLUSION

We currently have little data to show a correlation between erectile dysfunction and sexual structures. It would be necessary to have additional prospective studies evaluating the impact of an optimization on these sexual structures on erectile dysfunction.

Automatic segmentation of neurovascular bundle on mri using deep learning based topological modulated network

PURPOSE

Radiation damage on neurovascular bundles (NVBs) may be the cause of sexual dysfunction after radiotherapy for prostate cancer. However, it is challenging to delineate NVBs as organ-at-risks from planning CTs during radiotherapy. Recently, the integration of MR into radiotherapy made NVBs contour delineating possible. In this study, we aim to develop an MRI-based deep learning method for automatic NVB segmentation.

METHODS

The proposed method, named topological modulated network, consists of three subnetworks, that is, a focal modulation, a hierarchical block and a topological fully convolutional network (FCN). The focal modulation is used to derive the location and bounds of left and right NVBs', namely the candidate volume-of-interests (VOIs). The hierarchical block aims to highlight the NVB boundaries information on derived feature map. The topological FCN then segments the NVBs inside the VOIs by considering the topological consistency nature of the vascular delineating. Based on the location information of candidate VOIs, the segmentations of NVBs can then be brought back to the input MRI's coordinate system.

RESULTS

A five-fold cross-validation study was performed on 60 patient cases to evaluate the performance of the proposed method. The segmented results were compared with manual contours. The Dice similarity coefficient (DSC) and 95th percentile Hausdorff distance (HD95 ) are (left NVB) 0.81 ± 0.10, 1.49 ± 0.88 mm, and (right NVB) 0.80 ± 0.15, 1.54 ± 1.22 mm, respectively.

CONCLUSION

We proposed a novel deep learning-based segmentation method for NVBs on pelvic MR images. The good segmentation agreement of our method with the manually drawn ground truth contours supports the feasibility of the proposed method, which can be potentially used to spare NVBs during proton and photon radiotherapy and thereby improve the quality of life for prostate cancer patients.

Psychosexual functioning in cancer survivorship: What the pediatric oncologist needs to know

Sexual health may be disrupted in adolescents and young adults (AYAs) both during and after cancer treatment, irrespective of whether they are diagnosed in childhood, adolescence, or young adulthood. Unfortunately, oncology providers often underestimate the relevance of psychosexual issues for AYAs and underprioritize sexual health throughout treatment and survivorship. The purpose of this narrative review is to provide information on (a) the etiology of psychosexual dysfunction in childhood, adolescent, and young adult cancer patients and young adult survivors of childhood cancer; (b) strategies for communicating and evaluating potential sexual health issues of AYA patients/survivors; and (c) guidance for the practicing pediatric oncologist on how to address sexual health concerns with patients.

The Current Trend of Radiation Therapy for Patients with Localized Prostate Cancer

A recent approach to radiotherapy for prostate cancer is the administration of high doses of radiation to the prostate while minimizing the risk of side effects. Thus, image-guided radiotherapy utilizes advanced imaging techniques and is a feasible strategy for increasing the radiation dose. New radioactive particles are another approach to achieving high doses and safe procedures. Prostate brachytherapy is currently considered as a combination therapy. Spacers are useful to protect adjacent organs, specifically the rectum, from excessive radiation exposure.

Psychosexual functioning in cancer survivorship: What the pediatric oncologist needs to know

Sexual health may be disrupted in adolescents and young adults (AYAs) both during and after cancer treatment, irrespective of whether they are diagnosed in childhood, adolescence, or young adulthood. Unfortunately, oncology providers often underestimate the relevance of psychosexual issues for AYAs and underprioritize sexual health throughout treatment and survivorship. The purpose of this narrative review is to provide information on (a) the etiology of psychosexual dysfunction in childhood, adolescent, and young adult cancer patients and young adult survivors of childhood cancer; (b) strategies for communicating and evaluating potential sexual health issues of AYA patients/survivors; and (c) guidance for the practicing pediatric oncologist on how to address sexual health concerns with patients.

The Role of Salvage Radical Prostatectomy in Patients with Radiation-Resistant Prostate Cancer

There are multiple treatment strategies for patients with localized prostate adenocarcinoma. In intermediate- and high-risk patients, external beam radiation therapy demonstrates effective long-term cancer control rates comparable to radical prostatectomy. In patients who opt for initial radiotherapy but have a local recurrence of their cancer, there is no unanimity on the optimal salvage approach. The lack of randomized trials comparing surgery to other local salvage therapy or observation makes it difficult to ascertain the ideal management. A narrative review of existing prospective and retrospective data related to salvage radical prostatectomy after radiation therapy was undertaken. Based on retrospective and prospective data, post-radiation salvage radical prostatectomy confers oncologic benefits, with overall survival ranging from 84 to 95% at 5 years and from 52 to 77% at 10 years. Functional morbidity after salvage prostatectomy remains high, with rates of post-surgical incontinence and erectile dysfunction ranging from 21 to 93% and 28 to 100%, respectively. Factors associated with poor outcomes after post-radiation salvage prostatectomy include preoperative PSA, the Gleason score, post-prostatectomy staging, and nodal involvement. Salvage radical prostatectomy represents an effective treatment option for patients with biochemical recurrence after radiotherapy, although careful patient selection is important to optimize oncologic and functional outcomes.

Comparison of satisfaction with penile prosthesis implantation in patients with prostate cancer radiation therapy versus radical prostatectomy

Background

Penile prosthesis surgery (PPS) is a commonly used treatment for erectile dysfunction (ED), either as first-line therapy or in cases refractory to other treatment options. In patients with a urologic malignancy such as prostate cancer, surgical interventions like radical prostatectomy (RP) as well as non-surgical treatments such as radiation therapy can all induce ED. PPS as a treatment for ED has high satisfaction rates in the general population. Our aim was to compare sexual satisfaction in patients with prosthesis implantation for ED following RP versus ED following radiation therapy for prostate cancer.

Methods

A retrospective chart review from our institutional database was conducted to identify patients who underwent PPS at our institution from 2011 to 2021. Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) questionnaire data at least 6 months from implant operative date available was required for inclusion. Eligible patients were placed in one of two groups depending on etiology of ED-following RP or prostate cancer radiation therapy. To prevent crossover confounding; patients with history of pelvic radiation were excluded from the RP group and patients with history of RP were excluded from the radiation group. Data were obtained from 51 patients in the RP group and 32 patients in the radiation therapy group. Mean EDITS scores and additional survey questions were compared between the radiation and RP groups.

Results

There was a significant difference in mean survey responses for 8 of the 11 questions in the EDITS questionnaire between the RP group and the radiation group. Additional survey questions administered also found RP patients reported significantly higher rate of satisfaction with size of penis post-operatively versus the radiation group.

Conclusions

These preliminary findings, while requiring large-scale follow-up, suggest that there is greater sexual satisfaction and penile prosthesis device satisfaction in patients undergoing IPP placement following RP versus radiation therapy for prostate cancer. Use of validated questionnaires should continue to be utilized in quantifying device and sexual satisfaction following PPS.

Development of handheld induction heaters for magnetic fluid hyperthermia applications andin-vitroevaluation on ovarian and prostate cancer cell lines

Objective:Magnetic fluid hyperthermia (MFH) is a still experimental technique found to have a potential application in the treatment of cancer. The method aims to reach around 41 °C-47 °C in the tumor site by exciting magnetic nanoparticles with an externally applied alternating magnetic field (AMF), where cell death is expected to occur. Applying AMFs with high spatial resolution is still a challenge. The AMFs from current and prospective MFH applicators cover relatively large areas; being not suitable for patients having metallic implants near the treatment area. Thus, there will be a clinical need for smaller magnetic field applicators. To this end, a laparoscopic induction heater (LIH) and a transrectal induction heater (TRIH) were developed.Methods:Miniature 'pancake' coils were wound and inserted into 3D printed enclosures. Ovarian (SKOV-3, A2780) and prostate (PC-3, LNCaP) cancer cell lines were used to evaluate the instruments' capabilities in killing cancer cellsin vitro, using Synomag^®-D nanoparticles as the heat mediators. NIH3T3 normal cell lines were also used with both devices to observe if these cells tolerated the conditions applied.Results:Magnetic field intensities reached by the LIH and TRIH were 42.6 kA m^-1at 326 kHz and 26.3 kA m^-1at 303 kHz, respectively. Temperatures reached in the samples were 41 °C by the LIH and 43 °C by the TRIH. Both instruments successfully accomplished killing cancer cells, with minimal effects on normal cells.Conclusion:This work presents the first line of handheld medical induction heaters and have the potential to be a complement to existing cancer therapies.Significance:These instruments could enable the development of MFH modalities that will facilitate the clinical translation of this thermal treatment.

Sexual Dysfunction Among Adolescent and Young Adult Men Diagnosed with Cancer

Purpose: Adolescent and young adult (AYA) cancer patients frequently demonstrate sexual dysfunction; however, there is a lack of data quantifying the severity and frequency. Methods: Males aged 18-39 years, diagnosed with cancer of any kind and who were scheduled to begin, were actively receiving, or had completed cancer treatment within 6 months, were offered validated surveys during their oncology appointment. These surveys included the International Index of Erectile Function (IIEF-6), Masturbation Erection Index (MEI), 36-Item Short Form Survey, and 5-point Likert scales to assess their desire and ability to engage in sex and masturbation. Results: Forty subjects completed the IIEF survey with a mean score of 17.7 ± 11, erectile dysfunction (ED) prevalence accordingly was 58%. Thirty-eight subjects completed the MEI with a mean score of 25.3 ± 5.3, ED prevalence was again 58%. Age and IIEF scores demonstrated a statistically significant (p < 0.05, n = 38) Pearson's correlation coefficient of 0.40, patients younger than 30 years had an ED prevalence of 72% (mean IIEF 13), whereas patients aged 30 years and older had an ED prevalence of 45% (mean IIEF 22). All treatment modalities had ED rates >30%: chemotherapy demonstrated the highest prevalence at 64% (mean IIEF 17), whereas radiation therapy had the lowest prevalence at 33% (mean IIEF 23). Conclusion: This study demonstrates that the prevalence of sexual dysfunction among male AYA patients undergoing treatment for cancer is high. AYA oncologists should discuss potential sexual health concerns when treating this population. The exact cause of ED (non-organic vs. organic) within this group should be explored further.

Long-term Health-related Quality of Life in Patients on Active Surveillance for Prostate Cancer: A Systematic Review

CONTEXT

Active surveillance (AS) represents the preferred treatment option in patients with low-risk prostate cancer. Optimised patient selection has enabled more patients to be managed with AS for a longer time. Thus, there is growing interest in its effect on long-term quality of life compared with interventional management.

OBJECTIVE

To perform a systematic review evaluating the long-term patient-reported outcomes regarding mental health, and sexual and urinary function in patients on AS.

EVIDENCE ACQUISITION

We performed a systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. We included series assessing validated patient-reported outcomes of health-related quality of life, and sexual and urinary function in AS patients followed up for at least 5 yr.

EVIDENCE SYNTHESIS

Our search yielded 1854 citations, including 19 papers involving 3643 patients on AS, 14 651 patients receiving surgery or radiotherapy, and 2478 controls without prostate cancer. In ten studies, major differences were observed in sexual and urinary symptoms between groups, such as better sexual function and fewer irritative urinary symptoms in patients on AS, though overall functional outcomes were comparable. In all studies, health-related quality of life for patients on AS was better than, or similar to, that for patients who had undergone surgery or radiotherapy and comparable with that for individuals without cancer.

CONCLUSIONS

We observed differences in specific functional outcomes between patients on AS and surgery or radiotherapy, ≥5 yr after treatment. Patients on AS reported good quality of life, similar to that in individuals without prostate cancer. AS should continue to be a recommended management strategy for appropriately selected patients.

PATIENT SUMMARY

Active surveillance is an accepted pathway for patients with low-risk localised prostate cancer. Previous literature has shown that it did not negatively affect short-term quality of life. This review finds that long-term quality of life for these patients is similar to that for people without prostate cancer.

Single dose Tadalafil 5 mg in Muscle Invasive Bladder Cancer (MIBC) patient induce priapism: A case report and literature review

There are several etiology related to priapism with incidence is less than 0.01%. A 47-year-old man was referred to our Emergency Room with a chief complaint of persistent and painful erection for 3 days. Previously, the patient took Tadalafil 5 mg to overcome the complaints of erectile dysfunction that he felt after undergoing (TURBT) and external radiation treatment. The patient treated with epinephrine injection and distal shunting surgical procedure Minimal and single dose of tadalafil can cause priapism as in this case. Time interval between onset and therapy affect patient outcome.

Preservation of organs related to future sexual function during prostate stereotactic body radiotherapy: feasibility analysis through a re-optimization process

Preserving the quality of life and sexual function of patients with a localized prostate cancer remains a challenge for physicians and a major issue for patients. The present study aimed at demonstrating the feasibility of a dosimetric preservation of the sexual organs during prostate stereotactic radiotherapy planning. Patients from a single centre were retrospectively included in the RPAH-2 trial and randomized in Arm B if they presented with either a low- or intermediate- risk prostate cancer. A 37.5Gy in 5 fractions stereotactic body radiotherapy was delivered on the prostate gland. The corpus cavernosum, penile bulb and internal pudental arteries were retrospectively delineated before a re-optimization process. During this process, RPAH-2 trial dose constraints were respected on Gross Tumor Volume (GTV), Planning Target Volume and usual organs at risk. Pre-defined dose setting delivered to corpus cavernosum, penile bulb and internal pudental arteries were collected and compared before and after the re-optimization process. Nine patients were included in the study. A decrease of the median of each investigated dose setting (except D90% for corpus cavernosum) was reported after the re-optimization for corpus cavernosum, penile bulb and internal pudental arteries. Our study demonstrated the feasibility of a dosimetric preservation of structures considered as relevant to preserve sexual function after prostate stereotactic radiotherapy.

Impact of Radiation on Male Fertility

In today's time, environmental aspects, lifestyle changes, and person's health coalesce to form stupendous impact on the fertility. All of us are knowingly or unknowingly exposed to several types of radiation. These can lead to collection of early and delayed adverse effects of which infertility is one. A spurt in the number of cases of male infertility may be attributed to intense exposure to heat, pesticides, radiations, radioactivity, and other hazardous substances. Radiation both ionizing and non-ionizing can lead to adverse effects on spermatogenesis. Though thermal and non-thermal interactions of radiation with biological tissue can't be ruled out, most studies emphasize on the generation of reactive oxygen species (ROS). In addition, radiation pathophysiology also involves the role of kinases in cellular metabolism, endocrine system, genotoxicity, and genomic instability. In this study, we intend to describe a detailed literature on the impact of ionizing and non-ionizing radiation on male reproductive system and understand its consequences leading to the phenomenon of male infertility.

Radiation therapy-associated toxicity: Etiology, management, and prevention

Radiation therapy (RT) is a curative treatment for many malignancies and provides effective palliation in patients with tumor-related symptoms. However, the biophysical effects of RT are not specific to tumor cells and may produce toxicity due to exposure of surrounding organs and tissues. In this article, the authors review the clinical context, pathophysiology, risk factors, presentation, and management of RT side effects in each human organ system. Ionizing radiation works by producing DNA damage leading to tumor death, but effects on normal tissue may result in acute and/or late toxicity. The manifestation of toxicity depends on both cellular characteristics and affected organs' anatomy and physiology. There is usually a direct relationship between the radiation dose and volume to normal tissues and the risk of toxicity, which has led to guidelines and recommended dose limits for most tissues. Side effects are multifactorial, with contributions from baseline patient characteristics and other oncologic treatments. Technological advances in recent decades have decreased RT toxicity by dramatically improving the ability to deliver RT that maximizes tumor dose and minimizes organ dose. Thus the study of RT-associated toxicity is a complex, core component of radiation oncology training that continues to evolve alongside advances in cancer management. Because RT is used in up to one-half of all patients with cancer, an understanding of its acute and late effects in different organ systems is clinically pertinent to both oncologists and nononcologists.

Patient-Reported Outcomes From a Phase 3 Randomized Controlled Trial Exploring Optimal Sequencing of Short-Term Androgen Deprivation Therapy With Prostate Radiation Therapy in Localized Prostate Cancer

PURPOSE

Two phase 3 randomized controlled trials (OTT-0101, RTOG-9413) and a meta-analysis have shown an impact of sequencing of androgen deprivation therapy (ADT) and radiation therapy on oncologic outcomes in prostate cancer (PCa). However, the impact of sequencing strategy on health-related quality of life (HR-QoL) is unclear. Here, we present the patient-reported HR-QoL outcomes from the OTT-0101 study.

METHODS AND MATERIALS

In this trial, patients with PCa with Gleason score ≤7, clinical stage T1b to T3a, and prostate-specific antigen level <30 ng/mL were randomly assigned to neoadjuvant and concurrent ADT for 6 months, starting 4 months before or concurrent with prostate radiation therapy, or concurrent and adjuvant ADT for 6 months, starting simultaneously with prostate radiation therapy. HR-QoL was assessed using European Organisation for Research and Treatment of Cancer QoL questionnaires. Time until definitive deterioration was defined as time from random allocation to the first deterioration of at least 10 points with no further improvement of ≥10 points or if the patient experienced progression, died, or dropped out after deterioration, resulting in missing data. Stratified log-rank tests were applied for between-group comparisons of time-to-event estimates.

RESULTS

Overall, 393 patients (194 and 199 in the 2 arms, respectively) were evaluable, except 214 (101 and 113 in the 2 arms, respectively) for sexual function. Five-year rates of freedom from definitive deterioration of urinary symptoms, bowel symptoms, and sexual activity were 33.5%, 33.1%, and 38.5% in the neoadjuvant group and 34.1%, 35.4%, and 36.7% in the adjuvant group, respectively, with no significant between-group differences. The adjuvant approach was associated with a reduced risk of definitive deterioration of sexual function (hazard ratio, 0.68; 95% confidence interval, 0.49-0.94; P = .02). With respect to clinical relevance, the mean change in score for sexual function showed only a small to moderate difference favoring the adjuvant group at and beyond 3 years.

CONCLUSIONS

In this study, no differences were found in the bowel or urinary symptoms between the adjuvant and neoadjuvant approach. Considering a significant likelihood of type I and type II errors and because of a lack of a persistent and clinically meaningful between-group difference in mean score changes over time, our findings do not confer a clear and conclusive picture of the impact of sequencing strategy on sexual function.

Impact of prostatic radiation therapy on bladder contractility and innervation

AIMS

To determine the effect of prostatic radiation therapy (RT) on bladder contractility and morphology, and axon, or neuron profiles within the detrusor and major pelvic ganglia (MPG) in male rats.

METHODS

Male Sprague-Dawley rats (8 weeks) received a single dose of prostatic RT (0 or 22 Gy). Bladders and MPG were collected 2- and 10-weeks post-RT. Detrusor contractile responses to carbachol and electrical field stimulation (EFS) were measured. Bladders were stained with Masson's trichrome, and antibodies for nonspecific neuronal marker, cholinergic nerve marker choline acetyltransferase (ChAT), and alpha-smooth muscle actin. MPG gene expression was assessed by quantitative polymerase chain reaction for ubiquitin carboxy-terminal hydrolase L1 (Uchl1) and Chat.

RESULTS

At 2 weeks post-RT, bladder smooth muscle, detrusor cholinergic axon profiles, and MPG Chat gene expression were increased (p < .05), while carbachol and EFS-mediated contractions were decreased (p < .05). In contrast, at 10 weeks post-RT, nerve-mediated contractions were increased compared with control (p < .05), while bladder smooth muscle, detrusor cholinergic axon profiles, MPG Chat expression, and carbachol contractions had normalized. At both 2- and 10-weeks post-RT, there was no change in detrusor nonspecific axon profiles and MPG Uchl1 expression.

CONCLUSION

In a rat model, RT of the prostate and MPG was associated with early changes in MPG Chat gene expression, and bladder cholinergic axon profiles and smooth muscle content which resolved over time. After RT recovery, bladder contractility decreased early and increased by 10 weeks. Long-term changes to the MPG and increased bladder cholinergic axons may contribute to RT-induced bladder dysfunction in prostate cancer survivors.

The management of sexual dysfunction resulting from radiotherapy and androgen deprivation therapy to treat prostate cancer: A comparison of uro-oncology practice according to disease stage

OBJECTIVES

To establish current uro-oncology practice in the management of sexual dysfunction (SD) following radiotherapy (RT) and/or androgen deprivation therapy (ADT) to treat prostate cancer. To identify differences in approach to the management of SD according to disease stage.

SUBJECTS AND METHODS

A 14-question mixed methods survey was designed to assess the current UK practice. Closed- and open-ended questions were used to quantify results while allowing participants to expand on answers. The survey was distributed to members of the British Uro-Oncology Group at the 2019 annual meeting.

RESULTS

Surveys were completed by 63 uro-oncologists attending the annual meeting of the British Uro-Oncology Group (response rate 66%). The major issue highlighted was a difference in approach to managing SD according to disease stage. More than half of the participants (56%) said 'advanced stage of disease' was a barrier to discussing SD. Clinicians were less likely to discuss SD, take baseline assessments, refer to a specialist clinic or offer rehabilitation when dealing with patients with advanced disease. Only a minority said that the management of SD was primarily their responsibility (11%). Nearly all clinicians (92%) had access to SD clinics; however, the majority of clinicians did not routinely refer patients.

CONCLUSIONS

This study shows that men with advanced prostate cancer need better support in managing SD. Patients receiving long-term ADT are less likely to be offered any kind of help or intervention. Specific guidance on managing SD in this cohort may result in improvements in sexual function, emotional well-being, quality of life, mental health and confidence.

Male erectile function after treatment for colorectal cancer: a population-based cross-sectional study

AIM

The aim of this work was to determine the knowledge gap in the field of erectile function (EF) after colorectal cancer surgery and investigate and compare long-term male EF in colon and rectal cancer survivors in a national population.

METHOD

Danish male patients alive without evidence of recurrence who were treated for colon or rectal cancer between May 2001 and December 2014 were invited to participate. Using the International Index of Erectile Function (IIEF) score the derived dichotomized erectile dysfunction (ED) was defined as moderate/severe or no/mild. Patients were grouped based on type of surgery [colon resection, rectal resection (RR) or local resection] and stratified for stoma, preoperative radiotherapy (RT), age and American Society of Anesthesiologists (ASA) score.

RESULTS

Of 10 037 eligible patients, 4334 responded (43.18%). The EF score was significantly lower for RR (mean 12.14) compared with both colon resection (mean 15.82) and local resection (mean 14.81) (p < 0.0001). No significant difference between colon resection and local resection was found (p = 0.29). Both a stoma and the use of RT were independent risk factors for ED. After excluding patients with stoma and RT and adjusting for age and ASA score, RR still had a higher risk of ED (OR 1.42, CI 1.20-1.67) compared with colon resection.

CONCLUSION

RR has a negative affect on EF. No difference between patients who underwent colon resection and local resection was found. RT and stoma were independent risk factors for ED.

Conservative Therapy for Peyronie's Disease: a Contemporary Review of the Literature

PURPOSE OF REVIEW

To analyze the literature on current conservative treatment options for Peyronie's disease (PD).

RECENT FINDINGS

Conservative therapy with intralesional collagenase clostridium histolyticum (CCH) is safe and efficacious in either the acute or chronic phases of PD. Combination treatment with penile traction therapy (PTT) can produce even better results. While most PTT devices require extended periods of therapy up to 8 h per day, the RestoreX® device can be effective at 30-90 min per day. A variety of conservative therapies are available for treatment of PD. The available literature does not reveal any treatment benefit of oral therapies. Intralesional therapy is the mainstay conservative treatment of PD. Intralesional CCH therapy is the first Food and Drug Administration-approved intralesional therapy and represents the authors' preference for medical therapy. The most effective conservative management of PD likely requires a combination of therapies.

Erectile dysfunction and cancer: current perspective

Erectile dysfunction (ED) is one of the major but underreported concerns in cancer patients and survivors. It can lead to depression, lack of intimacy between the couple, and impaired quality of life. The causes of erectile dysfunction are psychological distress and endocrinal dysfunction caused by cancer itself or side effect of anticancer treatment like surgery, radiotherapy, chemotherapy and hormonal therapy. The degree of ED depends on age, pre-cancer or pre-treatment potency level, comorbidities, type of cancer and its treatment. Treatment options available for ED are various pharmacotherapies, mechanical devices, penile implants, or reconstructive surgeries. A complete evaluation of sexual functioning should be done prior to starting anticancer therapy. Management should be individualized and couple counseling should be an integral part of the anticancer treatment.

Relative Biological Effectiveness of High LET Particles on the Reproductive System and Fetal Development

During a space mission, astronauts are inevitably exposed to space radiation, mainly composed of the particles having high values of linear energy transfer (LET), such as protons, helium nuclei, and other heavier ions. Those high-LET particles could induce severer health damages than low-LET particles such as photons and electrons. While it is known that the biological effectiveness of a specified type of radiation depends on the distribution of dose in time, type of the cell, and the biological endpoint in respect, there are still large uncertainties regarding the effects of high-LET particles on the reproductive system, gamete, embryo, and fetal development because of the limitation of relevant data from epidemiological and experimental studies. To safely achieve the planned deep space missions to the moon and Mars that would involve young astronauts having reproductive functions, it is crucial to know exactly the relevant radiological effects, such as infertility of the parent and various diseases of the child, and then to conduct proper countermeasures. Thus, in this review, the authors present currently available information regarding the relative biological effectiveness (RBE) of high-LET particles on the deterministic effects related to the reproductive system and embryonic/fetal development for further discussions about the safety of being pregnant after or during a long-term interplanetary mission.

RhoA/ROCK pathway inhibitor ameliorates erectile dysfunction induced by radiation therapy in rats

OBJECTIVES

Prostate cancer (PCa) treatment with radiation therapy (RT) has an excellent cure rate. However, Radiation-induced Erectile Dysfunction (RiED) is a common and irreversible toxicity impacting quality of life, and there is no FDA approved specific drug for RiED. We previously showed that prostate RT increased RhoA/ROCK signaling in the cavernous nerve (CN) and penile tissues, which may lead to RiED in rats. In this study, we investigated whether RhoA/ROCK pathway inhibition by a specific inhibitor called Hydroxyfasudil (HF) can improve RiED in our well-established rat model.

MATERIALS/METHODS

Male Sprague-Dawley rats were randomized to the following groups: sham-RT, HF-only, RT-only, and RT + HF. Rats were either exposed to a single dose of 25 Gy prostate-confined RT or a sham procedure. 10 mg/kg HF or normal saline was injected intraperitoneally. Erectile function was evaluated by intracavernosal pressure (ICP) and mean arterial pressure (MAP) measurements at week 14 post-RT. Cavernous nerve (CN) injury was evaluated by transmission electron microscopy (TEM), and penile tissue fibrosis by Masson trichrome staining (MT).

RESULTS

We have found that the HF treatment prior to RT showed significant (p < 0.001) improvement in ICP/MAP ratio, area under the curve, and maximum ICP value, compared to RT-alone rats. Furthermore, RT + HF treated rats exhibited increased CN myelination and decreased axonal atrophy, comparted to RT-only. HF treatment showed significantly decreased penile tissue fibrosis (p < 0.05) compared to RT-alone treated rats.

CONCLUSION

Our results provide the first preclinical evidence that targeting RhoA/ROCK pathway by HF may provide a novel therapeutic option for the treatment of RiED.

Radiotherapy side effects: integrating a survivorship clinical lens to better serve patients

The Canadian Cancer Society estimated that 220,400 new cases of cancer would be diagnosed in 2019. Of the affected patients, more than 60% will survive for 5 years or longer after their cancer diagnosis. Furthermore, nearly 40% will receive at least 1 course of radiotherapy (rt). Radiotherapy is used with both curative and palliative intent: to treat early-stage or locally advanced tumours (curative) and for symptom management in advanced disease (palliative). It can be delivered systemically (external-beam rt) or internally (brachytherapy). Although technique improvements have drastically reduced the occurrence of rt-related toxicity, most patients still experience burdensome rt side effects (seffs). Radiotherapy seffs are local or locoregional, and manifest in tissues or organs that were irradiated. Side effects manifesting within weeks after rt completion are termed "early seffs," and those occurring months or years after treatment are termed "late seffs." In addition to radiation oncologists, general practitioners in oncology and primary care providers are involved in survivorship care and management of rt seffs. Here, we present an overview of common seffs and their respective management: anxiety, depression, fatigue, and effects related to the head-and-neck, thoracic, and pelvic treatment sites.

Erectile Dysfunction and Absorbed Dose to Penile Base Structures in a Randomized Trial Comparing Ultrahypofractionated and Conventionally Fractionated Radiation Therapy for Prostate Cancer

PURPOSE

To study the relationships between absorbed dose to penile base structures and erectile dysfunction (ED) in patients treated with ultrahypofractionated (UHF) radiation therapy (RT) or conventionally fractionated (CF) RT for prostate cancer.

METHODS AND MATERIALS

This dose-response study comprises 673 patients (57%) of the 1180 per-protocol patients included in the HYPO-RT-PC trial (median follow-up 5, years), where patients were randomized to CF (39 × 2.0 Gy, 8 weeks) or UHF (7 × 6.1 Gy, 2.5 weeks). No androgen deprivation therapy was allowed. Only patients with erectile function sufficient for intercourse at baseline and complete RT data were included in this study. Erectile function was assessed by physician at regular follow-ups. The main endpoint was severe ED (ED_s). The penile bulb (PB) and crus were retrospectively delineated on the treatment planning computed tomography scans. Dose-volume descriptors were derived from EQD2 converted dose matrices (α/β = 3 Gy). Univariable and multivariable Cox proportional hazard regression and logistic regression were used to find predictors for ED_S.

RESULTS

No significant difference in ED_s was found between CF and UHF. During the follow-up period, ED_s occurred in 27% of the patients in both treatment groups. Average (median) PB mean dose, D_mean, was 24.5 (20.2) in CF and 18.7 (13.1) Gy₃ in UHF. Age was the only significant predictor for ED_s in Cox analyses. All dose-volume variables contributed significantly in univariable logistic regression at 2-year follow-up. Age and near maximum dose (D_2%) were significant predictors for ED_s in multivariable logistic regression analyses at both 1 and 2 years.

CONCLUSIONS

The frequency of ED_S was similar in the CF and UHF treatment groups. Age at radiation therapy was the strongest predictor for ED_s, followed by dose to PB, and was most evident for younger patients. We propose D_{2 %} <50 Gy₃ and D_mean <20 Gy₃ to the PB as the primary objectives to be applied in the treatment planning process.

Impact of Pelvic Radiation Therapy on Inflatable Penile Prosthesis Reoperation Rates

INTRODUCTION

Considering that radiation therapy (RT) compromises soft tissue microvasculature, impairs wound healing, and causes cavernosal fibrosis, inflatable penile prosthesis (IPP) outcomes may be adversely affected in men treated with RT.

AIM

To compare IPP outcomes among those who had undergone prior RT vs a cohort who underwent radical prostatectomy (RP) before insertion of IPP.

METHODS

The Surveillance, Epidemiology, and End Results (SEER)-Medicare Database was queried for men with prostate cancer (PCa) who underwent RT (n = 83,277) or RP (n = 32,608) with subsequent IPP insertion between 2002 and 2013. Men who had undergone both RT and RP were excluded from the analysis.

MAIN OUTCOME MEASURE

The primary outcome was reoperation, defined by removal, revision, or replacement of the IPP.

RESULTS

We identified 350 men who received an IPP following RT and 653 who received an IPP following RP. Men who underwent RT were older (P < .01) and had more comorbidities (P < .01). There were no significant differences in overall reoperation rates at 90 days (P = .78), 1 year (P = .52), or 3 years (P = .48). Time-to-event analysis demonstrated that RT was not associated with an increased likelihood of overall reoperation (hazard ratio [HR] 1.46, 95% confidence interval [CI] 0.94-2.29, P = .09). There was no association between time from RT to IPP and overall reoperation rates.

CLINICAL IMPLICATIONS

Prior RT for the treatment of PCa does not impact the revision or removal rates of IPPs as compared with a cohort of non-radiated patients who underwent RP.

STRENGTH & LIMITATIONS

The strength includes the analysis of outcomes among a contemporary, nationwide cohort with robust follow-up. Using diagnosis and procedure codes, we were thoroughly able to capture reoperations. Limitations include the lack of specific indications for reoperation and inability to control for surgeon experience or technique.

CONCLUSION

IPP is a safe and effective treatment of erectile dysfunction that should be offered to men with a history of pelvic radiation who have failed medical therapy. Golan R, Patel NA, Sun T, et al. Impact of pelvic radiation therapy on inflatable penile prosthesis reoperation rates. J Sex Med 2018;15:1653-1658.

Evaluation of seminal vesicle volume variability in patients receiving radiotherapy to the prostate

Introduction:

Prostate positional variability has been widely explored with seminal vesicle (SV) variability, coming into the forefront only in recent years. While planning target volume (PTV) margins and preparation protocols ameliorate the effects of bladder and rectum volume changes on prostate, studies on SV variation have looked at only position, not volume variability.

Aim:

The aim of this study was to investigate whether the inter-fraction volume variability of the VSs can exist in patients receiving radiotherapy to the prostate.

Method:

SV variability was investigated by comparing four on-treatment cone beam computer tomography scans to a planning computer tomography (CT) image for two patients receiving prostate radiotherapy. For each case, variation in volumes (cm3) was compared with intra-observer variation.

Results:

SV volume variability was seen in both patients, with the largest change in volume being 78·38%. This variance was considerably (between 2 and 10 times) larger than the measured intra-observer variance.

Conclusion:

This study identified the potential for daily SV volume variability in patients receiving prostate radiotherapy. Future large-scale studies are warranted to identify the extent of this motion and potential clinical impact. Evidence-informed PTV margins and possible SV volume control protocols may need to be adopted.

Long-Term Follow Up of the Erectile Function of Testicular Cancer Survivors

The diagnosis of testicular cancer (TC) can have a considerable and persistent impact on a patient's sexuality, especially given its location. The high prevalence of TC in young adults, and the good prognosis, explain the great interest in sexual dysfunction and its influence on post-treatment quality of life. The aim of this study was to evaluate the impact of the diagnosis and treatments (inguinal orchiectomy and chemotherapy) on sex life. For this purpose, we recruited 241 TC patients attending the Laboratory of Seminology-Sperm Bank "Loredana Gandini" for sperm cryopreservation (mean age 31.3 ± 6.9 years) and 223 cancer-free healthy men who were undergoing andrological screening (mean age 32.0 ± 7.7 years). The IIEF-15 questionnaire was administered at the baseline (post-orchiectomy, pre-chemotherapy-T0) and at 6 (T1), 12 (T2), 18 (T3), 24 (T4), 48 months (T5) and >5 years (T6, median 96 months) after chemotherapy to all patients, to evaluate the following domains: erectile function (EF), orgasmic function (OF), sexual desire (SD), intercourse satisfaction (IS) and overall satisfaction (OS). A subgroup of patients also underwent blood sex hormone analysis for further correlations with IIEF scores. At the baseline, 37.7% of patients had erectile dysfunction (EF score <26) and all IIEF domains except OF showed significantly lower scores than in controls (p < 0.001). Long-term follow-up revealed persistently lower scores in TC survivors than in controls for EF, SD, IS, and OS. Furthermore, most IIEF domains did not improve significantly in TC patients during the duration of the follow-up, with the exception of EF, which showed a significant improvement from T2. Finally, no significant correlation was found between hormone levels (gonadotropin and testosterone) and IIEF-15 scores. In conclusion, TC and its treatment have a significant effect on sexuality. The absence of a clear correlation with biochemical hypogonadism suggests that this may to a large extent be due to the surgical procedure itself, or to the psychological impact of a cancer diagnosis.

Clarifying the Relative Impacts of Vascular and Nerve Injury That Culminate in Erectile Dysfunction in a Pilot Study Using a Rat Model of Prostate Irradiation and a Thrombopoietin Mimetic

PURPOSE

Radiation therapy (RT) offers an important and curative approach to treating prostate cancer, but it is associated with a high incidence of erectile dysfunction (ED). It is not clear whether the etiology of radiation-induced ED (RI-ED) is driven by RT-mediated injury to the vasculature, the nerves, or both. This pilot study sought to distinguish the effects of vascular and nerve injury in RI-ED by applying a vascular radioprotectant in a rat model of prostate RT.

METHODS

A single dose of the thrombopoietin mimetic (TPOm; RWJ-800088), previously shown to mitigate radiation-induced vascular injury, was administered 10 minutes after single-fraction conformal prostate RT. Nine weeks after RT, rats were assessed for erectile and arterial function. Nerve markers were quantified with reverse transcriptase polymerase chain reaction. Immunofluorescent microscopy further characterized vascular effects of RT and TPOm.

RESULTS

Sham animals and animals that received RT and TPOm showed significant arterial vasodilation in response to systemic hydralazine (24.1% ± 7.3% increase; P = .03 in paired t test). However, animals that received RT and vehicle were unable to mount a vasodilatory response (-7.4% ± 9.9% increase; P = .44 in paired t test). TPOm prevented RT-induced change in the penile artery cross-sectional area (P = .036), but it did not ameliorate cavernous nerve injury as evaluated by gene expression of neuronal injury markers. Despite significant structural and functional vascular protective effects and some trends for differences in nerve injury/recovery markers, TPOm did not prevent RI-ED at 9 weeks, as assessed by intracavernous pressure monitoring after cavernous nerve stimulation.

CONCLUSIONS

These data suggest that vascular protection alone is not sufficient to prevent RI-ED and that cavernous nerve injury plays a key role in RI-ED. Further research is required to delineate the multifactorial nature of RI-ED and to determine if TPOm with modified dosing regimens can mitigate against nerve injury either through direct or vascular protective effects.

Improving Male Reproductive Health After Childhood, Adolescent, and Young Adult Cancer: Progress and Future Directions for Survivorship Research

Reproductive health is a common concern and often a source of distress for male childhood, adolescent, and young adult cancer survivors. Clinical and epidemiologic research in survivor populations has identified alkylating agent chemotherapy, testicular radiation, and surgery or radiation to the genitourinary organs, lower spine, or the hypothalamic-pituitary region as risk factors for adverse reproductive outcomes, including impaired spermatogenesis, testosterone insufficiency, and sexual dysfunction. Much of the research on male survivors has focused on the outcome of fertility, using spermatogenesis, serum gonadotropins, and paternity as the measures. However, these studies often fail to account for the clinically relevant but difficult-to-quantify aspects of fertility such as sexual function, cancer-related delayed psychosocial development, medical comorbidities, and socioeconomic concerns. Clinical and basic science research has made significant contributions to improving reproductive outcomes for survivors, with recent advancements in the areas of fertility preservation, clinical assessment of reproductive function, and treatment of adverse reproductive outcomes. Furthermore, there is an emerging qualitative literature addressing the psychosexual aspects of male reproductive health, the clinical application of which will improve quality of life for survivors. This review summarizes the current survivorship literature on reproductive health outcomes for male survivors, including the epidemiology of impaired spermatogenesis, testosterone insufficiency, and sexual dysfunction; clinical and laboratory assessment of reproductive function; and established and investigational interventions to preserve reproductive function for patients newly diagnosed and survivors. Although survivorship research has made significant contributions to improving reproductive outcomes, additional scientific progress is needed in the areas of fertility preservation, risk assessment, and psychosexual support with the aim of optimizing reproductive health for current and future survivors.

Older Age, Early Symptoms and Physical Function are Associated with the Severity of Late Symptom Clusters for Men Undergoing Radiotherapy for Prostate Cancer

AIMS

To identify symptom clusters and predisposing factors associated with long-term symptoms and health-related quality of life after radiotherapy in men with prostate cancer.

MATERIALS AND METHODS

Patient-reported outcomes (PROs) data from the Medical Research Council RT01 radiotherapy with neoadjuvant androgen deprivation therapy trial of 843 patients were used. PROs were collected over 5 years with the University of California, Los Angeles Prostate Cancer Index (UCLA-PCI) and the 36 item Short-Form Health Survey (SF-36). Symptom clusters were explored using hierarchical cluster analysis. The association of treatment dose, baseline patient characteristics and early symptom clusters with the change in severity of PROs over 3 years was investigated with multivariate linear mixed effects models.

RESULTS

Seven symptom clusters of three or more symptoms were identified. The clusters were stable over time. The longitudinal profiles of symptom clusters showed the onset of acute symptoms during treatment for all symptom clusters and significant recovery by 6 months. Some clusters, such as physical health and sexual function, were adversely affected more than others by androgen deprivation therapy, and were less likely to return to pretreatment levels over time. Older age was significantly associated with decreased long-term physical function, physical health and sexual function (P < 0.001). Both baseline and acute symptom clusters were significant antecedents for impaired function and health-related quality of life at 3 years.

CONCLUSIONS

Men with poorer physical function and health before or during treatment were more likely to report poorer PROs at year 3. Early assessment using PROs and lifestyle interventions should be used to identify those with higher needs and provide targeted rehabilitation and symptom management.

Cavernous Nerve Injury by Radiation Therapy May Potentiate Erectile Dysfunction in Rats

PURPOSE/OBJECTIVES

Radiation-induced erectile-dysfunction (RiED) is one of the most common side effects of radiation therapy (RT) and significantly reduces the quality of life (QoL) of cancer patients. Approximately 50% of prostate cancer patients experience RiED within 3 to 5 years after completion of RT. A series of vascular, muscular, and neurogenic injuries after prostate RT lead to RiED; however, the precise role of RT-induced neurogenic injury in RiED has not been fully established. The cavernous nerves (CN) are postganglionic parasympathetic nerves located beside the prostate gland that assist in penile erection. This study was designed to investigate the role of CN injury, tissue damage, and altered signaling pathways in an RiED rat model.

METHODS AND MATERIALS

Male rats were exposed to a single dose of 25 Gy prostate-confined RT. Erectile function was evaluated by intracavernous pressure (ICP) measurements conducted both 9 and 14 weeks after RT. Neuronal injury was evaluated in the CN using quantitative polymerase chain reaction, conduction studies, transmission electron microscopy, and immunoblotting. Masson trichrome staining was performed to elucidate fibrosis level in penile tissues.

RESULTS

There were significant alterations in the ICP (P<.0001) of RT rats versus non-RT rats. TEM analysis showed decreased myelination, increased microvascular damage, and progressive axonal atrophy of the CN fibers after RT. Electrophysiologic analysis showed significant impairment of the CN conduction velocity after RT. RT also significantly increased RhoA/Rho-associated protein kinase 1 (ROCK1) mRNA and protein expression. In addition, penile tissue showed increased apoptosis and fibrosis 14 weeks after RT.

CONCLUSIONS

RT-induced CN injury may contribute to RiED; this is therefore a rationale for developing novel therapeutic strategies to mitigate CN and tissue damage. Moreover, further investigation of the RhoA/ROCK pathway's role in mitigating RiED is necessary.

Current Status of Targeted Radioprotection and Radiation Injury Mitigation and Treatment Agents: A Critical Review of the Literature

As more cancer patients survive their disease, concerns about radiation therapy-induced side effects have increased. The concept of radioprotection and radiation injury mitigation and treatment offers the possibility to enhance the therapeutic ratio of radiation therapy by limiting radiation therapy-induced normal tissue injury without compromising its antitumor effect. Advances in the understanding of the underlying mechanisms of radiation toxicity have stimulated radiation oncologists to target these pathways across different organ systems. These generalized radiation injury mechanisms include production of free radicals such as superoxides, activation of inflammatory pathways, and vascular endothelial dysfunction leading to tissue hypoxia. There is a significant body of literature evaluating the effectiveness of various treatments in preventing, mitigating, or treating radiation-induced normal tissue injury. Whereas some reviews have focused on a specific disease site or agent, this critical review focuses on a mechanistic classification of activity and assesses multiple agents across different disease sites. The classification of agents used herein further offers a useful framework to organize the multitude of treatments that have been studied. Many commonly available treatments have demonstrated benefit in prevention, mitigation, and/or treatment of radiation toxicity and warrant further investigation. These drug-based approaches to radioprotection and radiation injury mitigation and treatment represent an important method of making radiation therapy safer.