Erectile function after stereotactic body radiotherapy for localized prostate cancer

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.

A pooled long-term follow-up after radiotherapy for prostate cancer with and without a rectal hydrogel spacer: impact of hydrogel on decline in sexual quality of life

Purpose

The purpose of this study was to analyze the impact of prostate rectal spacers on sexual quality of life (QOL) following external beam radiation therapy (RT).

Methods and materials

Patient- reported QOL was evaluated using the Expanded Prostate Cancer Index Composite (EPIC). Patients were pooled from two sources: a randomized controlled trial and a non-randomized cohort of patients from a single institution. Both cohorts used the same spacing product and QOL instrument. Analysis was limited to those with good baseline pre-treatment sexual QOL (EPIC >/= 60). Differences in QOL summary score and individual items were assessed compared with baseline and between treatment arms.

Results

A total of 128 men had good baseline sexual function and were evaluated (64% with spacer and 36% without) with QOL data available for median 33 months (range: 2.5-69.4 months). Men without spacer were more likely to have declines in sexual function (p < 0.0001), bother (p = 0.0002), and sexual summary score (p < 0.0001). A minimally important difference of 10 points (1xMID) and 20 point (2xMID) was more likely without rectal spacer [10 points: odds ratio 3.53, (95% confidence interval 1.11-11.2), p = 0.032; 20 points: odds ratio 3.29, (95% confidence interval 1.16-9.33), p = 0.025]. Seven of 13 QOL items were statistically superior with hydrogel (six of nine functional and one of four bother), while no items were statistically superior for control. At baseline, more men treated with hydrogel had erections sufficient for intercourse; however, when analyzed only by the men with best baseline erectile potential and excluding those with worse function, the benefit of rectal spacing was maintained with a higher likelihood of preservation of erections sufficient for intercourse in those treated with hydrogel.

Conclusion

In this pooled analysis of QOL after prostate RT, the utilization of a hydrogel spacer was associated with better sexual QOL, less men with measurable declines in sexual QOL, and higher rates of adequate erectile function.

Association between overweight, obesity, and quality of life of patients receiving an anticancer treatment for prostate cancer: a systematic literature review

BACKGROUND

Prostate cancer (PCa) and obesity are two ever-increasing public health issues that can independently impair the quality of life (QOL) of affected patients. Our objective was to evaluate the impact of overweight and obesity on the QOL of patients with PCa receiving an anticancer treatment.

METHODS

We performed a systematic review of the literature using PubMed, Embase, Cochrane Library and Web of Science databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The search equation targeted studies that included PCa patients who had a body mass index (BMI) greater than 25 kg/m², who were receiving anticancer therapy, and whose QOL was analyzed according to validated or non-validated scores.

RESULTS

Of 759 identified articles, we selected 20 studies published between 2000 and 2019 of 12,529 patients treated for PCa, including 5549 overweight or obese patients. QOL assessment was performed using nine validated scales and two non-validated questionnaires. Of seven studies on radiotherapy, six found obesity to have a negative impact on patients' QOL (especially urinary, sexual, and bowel-related QOL). Thirteen studies assessed the QOL of patients who underwent radical prostatectomy, with a BMI > 25 kg/m² having no observed impact. In obese patients under 65 years of age and without comorbidities, nerve-sparing surgery appeared to limit the deterioration of QOL. Four studies on brachytherapy found discordant results. One study showed greater QOL impairment in obese patients receiving first-generation hormone therapy than in those with normal or decreased BMI. No study evaluated the QOL of overweight or obese patients receiving other types of systemic treatment.

CONCLUSION

Based on the published data, the level of evidence for an association between QOL and overweight or obesity in patients treated for PCa is not high. Prospective cohort studies including this type of patient population are warranted to answer this topical public health issue.

Better preservation of erectile function in localized prostate cancer patients with modern proton therapy: Is it cost-effective?

BACKGROUND

Stereotactic body radiation therapy (SBRT) has gradually been recognized as favorable curative treatment for localized prostate cancer (PC). However, the high rate of erectile dysfunction (ED) after traditional photon-based SBRT remains an ongoing challenge that greatly impacts the quality of life of PC survivors. Modern proton therapy allows higher conformal SBRT delivery and has the potential to reduce ED occurrence but its cost-effectiveness remains uninvestigated.

METHODS

A Markov decision model was designed to evaluate the cost-effectiveness of proton SBRT versus photon SBRT in reducing irradiation-related ED. Base-case evaluation was performed on a 66-year-old (median age of PC) localized PC patient with normal pretreatment erectile function. Further, stratified analyses were performed for different age groups (50, 55, 60, 65, 70, and 75 years) and threshold analyses were conducted to estimate cost-effective scenarios. A Chinese societal willingness-to-pay (WTP) threshold (37,653 US dollars [$])/quality-adjusted life-year [QALY]) was adopted.

RESULTS

For the base case, protons provided an additional 0.152 QALY at an additional cost of $7233.4, and the incremental cost-effectiveness ratio was $47,456.5/QALY. Protons was cost-effective for patients ≤62-year-old at the WTP of China (≤66-year-old at a WTP of $50,000/QALY; ≤73-year-old at a WTP of $100,000/QALY). For patients at median age, once the current proton cost ($18,000) was reduced to ≤$16,505.7 or the patient had a life expectancy ≥88 years, protons were cost-effective at the WTP of China.

CONCLUSIONS

Upon assumption-based modeling, the results of current study support the use of proton SBRT in younger localized PC patients who are previously potent, for better preservation of erectile function. The findings await further validation using data from future comparative clinical trials.

Ejaculatory Function Following Stereotactic Body Radiation Therapy for Prostate Cancer

BACKGROUND

Ejaculatory dysfunction is an important male quality of life issue which has not yet been studied in the setting of prostate stereotactic body radiation therapy (SBRT).

AIM

The purpose of this study is to evaluate ejaculatory function following SBRT for prostate cancer.

METHODS

Two hundred and thirty-one patients on a prospective quality of life study with baseline ejaculatory capacity treated with prostate SBRT from 2013 to 2019 were included in this analysis. Ejaculation was assessed via the Ejaculation Scale (ES-8) from the Male Sexual Health Questionnaire. Patients completed the questionnaire at 1, 3, 6, 9, 12, 18, and 24 months post-SBRT. Elderly patients (Age > 70) and those who received hormonal therapy were excluded from analysis. Patients were treated to 35-36.25 Gy in 5 fractions delivered with the CyberKnife Radiosurgical System (Accuray).

OUTCOMES

Ejaculatory function was assessed by ES-8 scores (range 4-40) with lower values representing increased interference or annoyance.

RESULTS

Median age at the time of treatment was 65 years. Median follow up was 24 months (IQR 19-24.5 months). 64.5% of patients had ED at baseline (SHIM < 22). The 2-year anejaculation rate was 15%. Mean composite ES-8 scores showed a decline in the first month following treatment then stabilized: 30.4 (start of treatment); 26.5 (1 month); 27.6 (3 month); 27.0 (6 month); 26.2 (9 month); 25.4 (12 month); 25.0 (18 month) and 25.4 (24 month). White race, higher pre-treatment SHIM (≥22), and higher ES-8 (≥31) at treatment start were significantly associated with a decreased probability of a clinically significant decline. Patient-reported ejaculate volume was significantly reduced at all time points post-SBRT. Ejaculatory discomfort peaked at 1 month and 9 months post-SBRT. Prior to treatment, 8.0% of men reported that they were very to extremely bothered by their ejaculatory dysfunction. The number of patients reporting this concern increased to 14.4% at one year and dropped to 11% at 24-months post-SBRT.

CLINICAL TRANSLATION

Patients undergoing prostate SBRT may experience meaningful changes in ejaculatory function and should be counseled on the trajectory of these side effects.

STRENGTHS & LIMITATIONS

This was a retrospective analysis of a prospectively maintained database. Subjective questionnaire responses captured limited aspects of ejaculatory function in this cohort.

CONCLUSION

The high incidence of moderate to extreme bother in ejaculatory function before and after SBRT suggests a need for novel approaches to improving ejaculation. Sholklapper T, Creswell M, Cantalino J, et al. Ejaculatory Function Following Stereotactic Body Radiation Therapy for Prostate Cancer. J Sex Med 2022;19:771-780.

Stereotactic Radiation Therapy versus Brachytherapy: Relative Strengths of Two Highly Efficient Options for the Treatment of Localized Prostate Cancer

Stereotactic body radiation therapy (SBRT) has become a valid option for the treatment of low- and intermediate-risk prostate cancer. In randomized trials, it was found not inferior to conventionally fractionated external beam radiation therapy (EBRT). It also compares favorably to brachytherapy (BT) even if level 1 evidence is lacking. However, BT remains a strong competitor, especially for young patients, as series with 10-15 years of median follow-up have proven its efficacy over time. SBRT will thus have to confirm its effectiveness over the long-term as well. SBRT has the advantage over BT of less acute urinary toxicity and, more hypothetically, less sexual impairment. Data are limited regarding SBRT for high-risk disease while BT, as a boost after EBRT, has demonstrated superiority against EBRT alone in randomized trials. However, patients should be informed of significant urinary toxicity. SBRT is under investigation in strategies of treatment intensification such as combination of EBRT plus SBRT boost or focal dose escalation to the tumor site within the prostate. Our goal was to examine respective levels of evidence of SBRT and BT for the treatment of localized prostate cancer in terms of oncologic outcomes, toxicity and quality of life, and to discuss strategies of treatment intensification.

[Radiation-induced sexual toxicity]

Oncosexuality has recently become a new supportive care mission. Sexual morbidity is, routinely, underestimated and must be questioned. We report here the most frequent disorders for men and for women, how to prevent them and how to treat them.

[Ultra-hypofractionated radiotherapy for the treatment of localized prostate cancer: Results, limits and prospects]

Still an emerging approach a few years ago, stereotactic body radiation therapy (SBRT) has ranked as a valid option for the treatment of localized prostate cancer. Inherent properties of prostatic adenocarcinoma (low α/β) make it the perfect candidate. We propose a critical review of the literature trying to put results into perspective to identify their strengths, limits and axes of development. Technically sophisticated, the stereotactic irradiation of the prostate is well tolerated. Despite the fact that median follow-up of published data is still limited, ultra-hypofractionated radiotherapy seems very efficient for the treatment of low and intermediate risk prostate cancers. Data seem satisfying for high-risk cancers as well. New developments are being studied with a main interest in treatment intensification for unfavorable intermediate risk and high-risk cancers. Advantage is taken of the sharp dose gradient of stereotactic radiotherapy to offer safe reirradiation to patients with local recurrence in a previously irradiated area.

Localized and Locally Advanced Prostate Cancer: Treatment Options

BACKGROUND

There are many treatment options for localized and locally advanced prostate cancer with radiotherapy and surgery representing the main local therapeutic strategies.

SUMMARY

Depending on the risk of disease recurrence, we can stratify patients into low-, intermediate- and high-risk groups, which will guide patients' treatment. For low-risk patients, active surveillance is an option. Brachytherapy is also an option for low- and intermediate-risk patients and can be used as a boost following external beam radiotherapy for high-risk patients. For intermediate- and high-risk patients, radical prostatectomy and radiotherapy should be considered. Moreover, in addition to radiotherapy, concomitant androgen deprivation therapy may be needed. Finally, after radical prostatectomy and depending on pathological, biological and clinical factors, radiotherapy ± androgen deprivation therapy can be proposed as an adjuvant or salvage treatment. Key Messages: With radiotherapy and surgery being well-established treatment options for localized prostate cancer patients with equally good overall survival rates, priority must be given to patients' choice concerning the logistics and the toxicity profile of each option.

Dosimetric feasibility of neurovascular bundle-sparing stereotactic body radiotherapy with periprostatic hydrogel spacer for localized prostate cancer to preserve erectile function

Objective:

We aim to test the hypothesis that neurovascular bundle (NVB) displacement by rectal hydrogel spacer combined with NVB delineation as an organ at risk (OAR) is a feasible method for NVB-sparing stereotactic body radiotherapy.

Methods:

Thirty-five men with low- and intermediate-risk prostate cancer who underwent rectal hydrogel spacer placement and pre-, post-spacer prostate MRI studies were treated with prostate SBRT (36.25 Gy in five fractions). A prostate radiologist contoured the NVB on both the pre- and post-spacer T2W MRI sequences that were then registered to the CT simulation scan for NVB-sparing radiation treatment planning. Three SBRT treatment plans were developed for each patient: (1) no NVB sparing, (2) NVB-sparing using pre-spacer MRI, and (3) NVB-sparing using post-spacer MRI. NVB dose constraints include maximum dose 36.25 Gy (100%), V34.4 Gy (95% of dose) <60%, V32Gy <70%, V28Gy <90%.

Results:

Rectal hydrogel spacer placement shifted NVB contours an average of 3.1 ± 3.4 mm away from the prostate, resulting in a 10% decrease in NVB V34.4 Gy in non-NVB-sparing plans (p < 0.01). NVB-sparing treatment planning reduced the NVB V34.4 by 16% without the spacer (p < 0.01) and 25% with spacer (p < 0.001). NVB-sparing did not compromise PTV coverage and OAR endpoints.

Conclusions:

NVB-sparing SBRT with rectal hydrogel spacer significantly reduces the volume of NVB treated with high-dose radiation. Rectal spacer contributes to this effect through a dosimetrically meaningful displacement of the NVB that may significantly reduce RiED. These results suggest that NVB-sparing SBRT warrants further clinical evaluation.

Advances in knowledge:

This is a feasibility study showing that the periprostatic NVBs can be spared high doses of radiation during prostate SBRT using a hydrogel spacer and nerve-sparing treatment planning.

Prostate Stereotactic Body Radiation Therapy: An Overview of Toxicity and Dose Response

PURPOSE

Ultrahypofractionationed radiation therapy for prostate cancer is increasingly studied and adopted. The American Association of Physicists in Medicine Working Group on Biological Effects of Hypofractionated Radiotherapy therefore aimed to review studies examining toxicity and quality of life after stereotactic body radiation therapy (SBRT) for prostate cancer and model its effect.

METHODS AND MATERIALS

We performed a systematic PubMed search of prostate SBRT studies published between 2001 and 2018. Those that analyzed factors associated with late urinary, bowel, or sexual toxicity and/or quality of life were included and reviewed. Normal tissue complication probability modelling was performed on studies that contained detailed dose/volume and outcome data.

RESULTS

We found 13 studies that examined urinary effects, 6 that examined bowel effects, and 4 that examined sexual effects. Most studies included patients with low-intermediate risk prostate cancer treated to 35-40 Gy. Most patients were treated with 5 fractions, with several centers using 4 fractions. Endpoints were heterogeneous and included both physician-scored toxicity and patient-reported quality of life. Most toxicities were mild-moderate (eg, grade 1-2) with a very low overall incidence of severe toxicity (eg, grade 3 or higher, usually <3%). Side effects were associated with both dosimetric and non-dosimetric factors.

CONCLUSIONS

Prostate SBRT appears to be overall well tolerated, with determinants of toxicity that include dosimetric factors and patient factors. Suggested dose constraints include bladder V(Rx Dose)Gy <5-10 cc, urethra Dmax <38-42 Gy, and rectum Dmax <35-38 Gy, though current data do not offer firm guidance on tolerance doses. Several areas for future research are suggested.

Risk of erectile dysfunction after modern radiotherapy for intact prostate cancer

BACKGROUND

Erectile dysfunction (ED) is a prevalent side effect of prostate cancer treatment. We hypothesized that the previously reported rates of ED may have improved with the advent of modern technology. The purpose of this project was to evaluate modern external beam radiotherapy and brachytherapy techniques to determine the incidence of radiotherapy (RT) induced ED.

METHODS

A systematic review of the literature published between January 2002 and December 2018 was performed to obtain patient reported rates of ED after definitive external beam radiotherapy, ultrafractionated stereotactic radiotherapy, and brachytherapy (BT) to the prostate in men who were potent prior to RT. Univariate and multivariate analyses of radiation dose, treatment strategy, and length of follow-up were analyzed to ascertain their relationship with RT-induced ED.

RESULTS

Of 890 articles reviewed, 24 met inclusion criteria, providing data from 2714 patients. Diminished erectile function status post RT was common and similar across all studies. The median increase in men reporting ED was 17%, 26%, 23%, and 23%, 3DCRT, IMRT, low dose rate BT, and SBRT, respectively, at 2-year median follow-up.

CONCLUSION

ED is a common side effect of RT. Risk of post-RT ED is similar for both LDR brachytherapy and external beam RT with advanced prostate targeting and penile-bulb sparing techniques utilized in modern RT techniques.

Stereotactic Body Radiotherapy for Prostate Cancer

Prostate cancer remains the most common and second most deadly cancer diagnosed amongst U.S. men. External beam radiotherapy is a standard-of-care definitive treatment option for localized prostate cancer and historically constituted an 8–9-week treatment course comprised of 39–45 doses of 1.8–2.0 Gy each (conventional fractionation, CF). Based on the notion that prostate cancer may respond favorably to a higher dose per day, considerable research efforts have been focused on characterizing the safety and efficacy profile of shorter and shorter radiation courses. Ultrahypofractionation (UHF) involves condensing the radiation course into just 5–7 treatments of 6–8 Gy each. When utilizing modern techniques that allow the precise sculpting of a dose distribution that delivers high doses to the prostate and lower doses to surrounding normal tissues over five or fewer treatments, this treatment is called stereotactic body radiotherapy (SBRT). Two randomized trials (HYPO-RT-PC and PACE-B) have compared UHF to longer radiation courses. The former demonstrated that UHF and CF have similar long-term toxicity and efficacy, while the latter demonstrated that modern SBRT has equivalent short-term toxicity as well. A separate report from a consortium of studies data provides prospective, albeit nonrandomized, data supporting the longer-term safety and efficacy of SBRT specifically. Thus, mounting high-level evidence suggests that SBRT is an acceptable standard care of option for men with localized prostate cancer.

Challenges in Reporting the Effect of Radiotherapy on Erectile Function

BACKGROUND

Erectile dysfunction (ED) is the most common side effect of prostate radiotherapy (RT), but reported rates over time and across modalities have varied widely.

AIM

To evaluate the published literature between 2002 and 2018 for high quality data utilizing prospectively gathered patient-reported ED, and to summarize the challenges in reporting of RT-induced ED (RIED).

METHODS

A PubMed search and literature review was performed to identify articles describing rates of ED before and after definitive external beam RT or brachytherapy without androgen deprivation.

OUTCOMES

Patient-reported ED, patient and treatment variables, and study follow-up constituted the main outcomes of this study.

RESULTS

24 articles were identified, reporting RIED rates between 17% and 90%. Variables contributing to this range included patient, treatment, and study characteristics known to impact ED reporting.

CLINICAL IMPLICATIONS

For future studies, we recommend the use of validated patient-reported questionnaires and reporting of baseline function and comorbidities, RT type and dose, and use of androgen deprivation therapy and erectile aids at the time of ED measurement. With sufficient follow-up to understand the late nature of RIED, these recommendations will improve comparison of results between studies and the applicability of results to patients undergoing pretreatment counseling regarding the risks of RIED.

STRENGTHS & LIMITATIONS

The literature search and formulation of results were based on a broad understanding of the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines and the literature, but because of the focus on data reporting, a comprehensive systematic review of all RIED literature was not performed.

CONCLUSION

Reported rates of ED after RT vary widely due to differences in patients' baseline reported erectile function, age, comorbidities, and characteristics of the treatment delivered. The methodology of ED measurement has significant impact on the applicability and comparability of results to other studies and clinical practice. Nukala V, Incrocci L, Hunt AA, et al. Challenges in Reporting the Effect of Radiotherapy on Erectile Function. J Sex Med 2020;17:1053-1059.

1.5 T MR-guided and daily adapted SBRT for prostate cancer: feasibility, preliminary clinical tolerability, quality of life and patient-reported outcomes during treatment

Background

Unity Elekta is a unique magnetic resonance (MR)-linac that conjugates a 1.5 Tesla MR unit with a 7 MV flattening filter free accelerator.A prospective observational study for the clinical use of Elekta Unity is currently ongoing in our department. Herein, we present our preliminary report on the feasibility, quality of life, and patient-reported outcomes measures (PROMs) for localized prostate cancer (PC) treated with stereotactic body radiotherapy (SBRT).

Methods

The SBRT protocol consisted of a 35 Gy schedule delivered in 5 fractions within 2 weeks. Toxicity and quality of life (QoL) were assessed at baseline and after treatment using the Common Terminology Criteria for Adverse Events v5.0, International Prostatic Symptoms Score (IPSS), ICIQ-SF, IIEF-5, and EORTC-QLQ-C30 and PR-25 questionnaires.

Results

Between October 2019 and January 2020, 25 patients with localized PC were recruited. The median age was 68 years (range, 54–82); 4 were low risk, 11 favorable intermediate risk (IR) and 10 unfavorable IR. Median iPSA was 6.8 ng/ml (range, 1–19), and 9 of these patients (36%) received concurrent androgen deprivation therapy. Median prostate volume was 36 cc (range, 20–61); median baseline IPSS was 5 (range, 0–10). Median time for fraction was 53 min (range, 34–86); adaptive strategy with daily critical structure and target re-contouring and daily replanning (adapt to shape) was performed in all cases. No grade ≥ 3 adverse event was observed, three patients (12%) reported grade 2 acute genitourinary toxicity (urinary frequency, urinary tract pain and urinary retention), while only one patient reported mild rectal pain. No relevant deteriorations were reported in PROMs.

Conclusion

To the best of our knowledge, this is the first experience reporting feasibility, clinician-reported outcome measurements, and PROMs for 1.5 T MR-guided adaptive SBRT for localized prostate cancer. The preliminary data collected here report optimal safety and excellent tolerability, as also confirmed by PROMs questionnaires. Moreover, the data on technical feasibility and timing of online daily adapted planning and delivery are promising. More mature data are warranted.

Trial registration

Date of approval April 2019 and numbered MRI/LINAC n°23,748.

Image-guided dose-escalated radiation therapy for localized prostate cancer with helical tomotherapy

PURPOSE

To evaluate treatment outcomes for patients with localized prostate cancer who were treated with dose-escalated primary image-guided radiation therapy (IGRT).

METHODS

We retrospectively analyzed 88 consecutive patients treated using helical tomotherapy with daily megavoltage CTs (MVCT). Patients were prescribed daily doses of 1.8 Gy to the planning target volume (PTV) and 2 Gy to the clinical target volume (CTV). Low- and favorable intermediate-risk patients received a minimum total dose of 72 Gy to the PTV and up to 80 Gy to the CTV. Unfavorable intermediate-risk and high-risk patients received a minimum total dose of 75.6 Gy to the PTV and up to 84 Gy to the CTV. We assessed freedom from biochemical relapse (FFBF), 5‑year biochemical recurrence-free survival (5-bRFS), distant metastasis-free survival (5-dMFS), and cancer-specific survival (5-CSS) as well as acute and late genitourinary (GU) and gastrointestinal (GI) toxicity.

RESULTS

Among our cohort, 11.4% were low-risk, 50% intermediate-risk, and 38.6% high-risk patients according to the D'Amico criteria. Median follow-up was 66 months (range 8-83 months). FFBF was 100%, 97.7%, and 90.7%; 5‑bRFS was 100%, 92.8%, and 70.4%; 5‑dMFS was 100%, 92.7%, and 70.4%; and 5‑CSS was 100%, 97.4%, and 89.8% for low-, intermediate-, and high-risk patients, respectively. Grades 2 and 3 toxicity occurred at the following rates: acute GU toxicity 39.8% and 1.1%, acute GI toxicity 12.5% and 0%, late GU toxicity 19.3% and 4.5%, and late GI toxicity 4.5% and 1.1% of patients, respectively. No toxicity >grade 3 was observed.

CONCLUSION

Risk-adapted dose-escalated IGRT with helical tomotherapy of up to 84 Gy is a feasible and well-tolerable treatment scheme with promising oncological results.

Testosterone Levels and Sexual Quality of Life After Stereotactic Body Radiation Therapy for Prostate Cancer: A Multi-Institutional Analysis of Prospective Trials

PURPOSE

The impact of higher scatter doses per fraction on testicular function and quality of life after prostate stereotactic body radiation therapy (SBRT) is poorly studied.

METHODS AND MATERIALS

Six hundred thirty-six patients treated with SBRT for low- to intermediate-risk prostate cancer from 2009 to 2014 were included. Changes in testosterone and in sexual and hormonal domain scores on the Expanded Prostate Cancer Index Composite-26 (EPIC) questionnaire over a 24-month period were evaluated via a 1-sided t test. EPIC score changes were evaluated in comparison with a distribution-based minimal clinically important difference threshold, wherein changes of greater than one half or greater than one third of the standard deviation in each domain were considered as medium-sized or small-sized effects, respectively.

RESULTS

Median and mean percent changes in testosterone at the 3- to 6-month, 7- to 12-month, 13- to 18-month, and 19- to 24-month time periods were -13.41% and -4.49% (P = .02); -12.23% and -2.77% (P = .13); -11.20% and -0.29% (P = .47); -5.00% and + 1.20% (P = .65). When analyzed after dividing the cohort into 3 groups based on baseline testosterone values using tertiles, testosterone tended to increase in patients in the first group and decrease in patients in the third group. Overall, the decline in EPIC hormonal domain scores never exceeded the threshold for a small-sized effect, though the decline in EPIC sexual domain scores did pass this threshold at the 19- to 24-month time period (mean 10.90 point decline). This decline was not present when groups were examined individually.

CONCLUSIONS

In this large cohort of prospectively followed patients, there was a transient decline in testosterone shortly after SBRT that normalized by 24 months posttreatment. There was no significant change in EPIC hormonal domain scores. A significant decline in EPIC sexual domain scores, consistent with a small-sized clinically detectable difference, manifested between 19 and 24 months of follow-up. These results are consistent with testosterone decline patterns and sexual function changes seen after other forms of photon-based radiation therapy.