A comparative study of quality of life in patients with localized prostate cancer treated at a single institution: Stereotactic ablative radiotherapy or external beam+high dose rate brachytherapy boost

A Systematic Review of the Efficacy and Toxicity of Brachytherapy Boost Combined with External Beam Radiotherapy for Nonmetastatic Prostate Cancer

CONTEXT

The optimum use of brachytherapy (BT) combined with external beam radiotherapy (EBRT) for localised/locally advanced prostate cancer (PCa) remains uncertain.

OBJECTIVE

To perform a systematic review to determine the benefits and harms of EBRT-BT.

EVIDENCE ACQUISITION

Ovid MEDLINE, Embase, and EBM Reviews-Cochrane Central Register of Controlled Trials databases were systematically searched for studies published between January 1, 2000 and June 7, 2022, according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. Eligible studies compared low- or high-dose-rate EBRT-BT against EBRT ± androgen deprivation therapy (ADT) and/or radical prostatectomy (RP) ± postoperative radiotherapy (RP ± EBRT). The main outcomes were biochemical progression-free survival (bPFS), severe late genitourinary (GU)/gastrointestinal toxicity, metastasis-free survival (MFS), cancer-specific survival (CSS), and overall survival (OS), at/beyond 5 yr. Risk of bias was assessed and confounding assessment was performed. A meta-analysis was performed for randomised controlled trials (RCTs).

EVIDENCE SYNTHESIS

Seventy-three studies were included (two RCTs, seven prospective studies, and 64 retrospective studies). Most studies included participants with intermediate-or high-risk PCa. Most studies, including both RCTs, used ADT with EBRT-BT. Generally, EBRT-BT was associated with improved bPFS compared with EBRT, but similar MFS, CSS, and OS. A meta-analysis of the two RCTs showed superior bPFS with EBRT-BT (estimated fixed-effect hazard ratio [HR] 0.54 [95% confidence interval {CI} 0.40-0.72], p < 0.001), with absolute improvements in bPFS at 5-6 yr of 4.9-16%. However, no difference was seen for MFS (HR 0.84 [95% CI 0.53-1.28], p = 0.4) or OS (HR 0.87 [95% CI 0.63-1.19], p = 0.4). Fewer studies examined RP ± EBRT. There is an increased risk of severe late GU toxicity, especially with low-dose-rate EBRT-BT, with some evidence of increased prevalence of severe GU toxicity at 5-6 yr of 6.4-7% across the two RCTs.

CONCLUSIONS

EBRT-BT can be considered for unfavourable intermediate/high-risk localised/locally advanced PCa in patients with good urinary function, although the strength of this recommendation based on the European Association of Urology guideline methodology is weak given that it is based on improvements in biochemical control.

PATIENT SUMMARY

We found good evidence that radiotherapy combined with brachytherapy keeps prostate cancer controlled for longer, but it could lead to worse urinary side effects than radiotherapy without brachytherapy, and its impact on cancer spread and patient survival is less clear.

Stereotactic pelvic radiotherapy with HDR boost for dose escalation in intermediate and high-risk prostate cancer (SPARE): Efficacy, toxicity and quality of life

BACKGROUND

The ASCO/CCO guidelines recommend brachytherapy (BT) boost for eligible intermediate- (IR) or high-risk (HR) prostate cancer (PCa) patients. We present efficacy, toxicity and quality-of-life (QoL) outcomes in patients treated on a prospective protocol of MRI dose-painted high-dose-rate BT boost (HDR-BT) followed by 5-fraction pelvic radiotherapy (RT) and 6-18 months of androgen deprivation therapy (ADT).

METHODS

In this phase I/II study, IR or HR PCa patients received HDR-BT 15 Gy × 1 to prostate and up to 22.5 Gy to MRI nodule, followed by 25 Gy in 5, weekly fractions to pelvis. Toxicity was assessed using CTCAEv3.0, and QoL was captured using EPIC questionnaire. Biochemical failure (BF; nadir + 2.0), and proportion of patients with PSA < 0.4 ng/ml at 4-years (4yPSARR) were evaluated. A minimally clinically important change (MCIC) was recorded if QoL score decreased >0.5 standard deviation of baseline scores.

RESULTS

Thirty-one patients (NCCN 3.2% favorable IR, 48.4% unfavorable IR and 48.4% HR) completed treatment with a median follow-up of 61 months. Median D90 to MR nodule was 19.0 Gy and median prostate V100% was 96.5%. The actuarial 5-year BF rate was 18.2%, and the 4yPSARR was 71%. One patient died of PCa. Acute grade 2 and 3 toxicities: GU: 50%, 7%, and GI: 3%, none, respectively. Late grade 2 and 3 toxicities were: GU: 23%, 3%, and GI: 7%, none, respectively. Proportion of patients with MCIC was 7.7% for urinary domain and 32.0% for bowel domain.

CONCLUSIONS

This novel treatment protocol incorporating MRI dose-painted HDR-BT boost and 5-fraction pelvic RT with ADT is well tolerated.

Prostate high dose-rate brachytherapy as monotherapy for prostate cancer: Late toxicity and patient reported outcomes from a randomized phase II clinical trial

BACKGROUND AND PURPOSE

Long-term toxicity of high dose-rate brachytherapy as monotherapy for prostate cancer is not well defined. We report late toxicity and health related quality of life (HRQOL) changes from a randomized phase II clinical trial of two different fractionation schemes.

MATERIALS AND METHODS

Eligible patients had NCCN low or intermediate risk prostate cancer. 170 patients were randomized to receive either a single 19 Gy or two-fractions of 13.5 Gy one week apart. Toxicity was measured using Common Terminology for Adverse Events (CTCAE) v4.0, and HRQOL was measured using the Expanded Prostate Index Composite (EPIC).

RESULTS

Median follow-up was 63 months. The 5-year cumulative incidence of Grade 2 or higher genitourinary (GU) and gastrointestinal (GI) toxicity was 62% and 12% in the single-fraction arm, and 47% and 9% in the two-fraction arm, respectively. Grade 3 GU toxicity was only seen in the single fraction arm with a cumulative incidence of 2%. The 5-year prevalence of Grade 2 GU toxicity was 29% and 21%, in the single- and two-fraction arms, respectively, with Grade 2 GI toxicity of 1% and 2%. Beyond the first year, no significant differences in mean urinary HRQOL were seen compared to baseline in the two-fraction arm, in contrast to the single-fraction arm where a decline in urinary HRQOL was seen at 4 and 5 years. Sexual HRQOL was significantly reduced in both treatment arms at all timepoints, with no changes in the bowel domain.

CONCLUSIONS

HDR monotherapy is well tolerated with minimal impact on HRQOL.

Stereotactic Ablative Body Radiotherapy for Intermediate- or High-Risk Prostate Cancer

Stereotactic ablative radiotherapy (SABR) is a relatively novel form of high precision radiotherapy. For low- and intermediate risk patients, ultrahypofractionation (UHF - more than 5 Gy per day) has been compared to conventionally fractionated or moderately hypofractionated radiotherapy in two large randomized studies. A third smaller randomized study examined the question of the optimal frequency of treatments. The results of these studies will be reviewed. SABR for high risk prostate cancer has been shown to be feasible and is well tolerated with careful planning and setup techniques. However, there is currently insufficient data supporting its use for high-risk patients to offer SABR outside of a clinical trial. SABR costs less to the radiotherapydepartments and, the patient, as well as increasing system capacity. Therefore, it has the potential to be widely adopted in the next few years.

Evaluating the Tolerability of a Simultaneous Focal Boost to the Gross Tumor in Prostate SABR: A Toxicity and Quality-of-Life Comparison of Two Prospective Trials

PURPOSE

Dose-escalated stereotactic ablative radiotherapy (SABR) to the whole prostate may be associated with better outcomes but has a risk of increased toxicity. An alternative approach is to focally boost the dominant intraprostatic lesion (DIL) seen on magnetic resonance imaging. We report the toxicity and quality-of-life (QOL) outcomes of 2 phase 2 trials of prostate and pelvic SABR, with or without a simultaneous DIL boost.

METHODS AND MATERIALS

The first trial treated patients with high-risk prostate cancer to a dose of 40 Gy to the prostate and 25 Gy to the pelvis in 5 fractions. The second trial treated patients with intermediate-risk and high-risk prostate cancer to a dose of 35 Gy to the prostate, 25 Gy to the pelvis, and a DIL boost up to 50 Gy in 5 fractions. Acute toxicities, late toxicities, and QOL were assessed.

RESULTS

Thirty patients were enrolled in each trial. In the focal boost cohort, the median DIL D90% was 48.3 Gy. There was no significant difference in acute grade ≥2 gastrointestinal or genitourinary toxicity between the 2 trials or in cumulative worst late gastrointestinal or genitourinary toxicity up to 24 months. There was no significant difference in QOL domain scores or minimally clinical important change between the 2 trials.

CONCLUSIONS

Prostate and pelvic SABR with a simultaneous DIL boost was feasible. Acute grade ≥2 toxicity, late toxicity, and QOL seemed to be comparable to a cohort that did not receive a focal boost. Further follow-up will be required to assess long-term outcomes, and randomized data are required to confirm these findings.

Two versus five stereotactic ablative radiotherapy treatments for localized prostate cancer: A quality of life analysis of two prospective clinical trials

PURPOSE

Stereotactic ablative radiotherapy (SABR) is appealing for prostate cancer (PCa) due to low α/β, and increasing the dose per fraction could improve the therapeutic index and lead to a better quality of life (QOL). Here we report the outcomes of a QOL comparison between two phase II clinical trials: two vs. five fraction prostate SABR.

METHODS

Patients had low or intermediate risk PCa. The doses prescribed were 26 Gy/2 and 40 Gy/5. Expanded prostate cancer index composite was collected. Urinary, bowel and sexual domains were analyzed. Minimal clinically important change (MCIC) was defined as >0.5 standard deviation.

RESULTS

30 and 152 patients were treated with 2-fraction and 5-fraction SABR. Median follow-up was 55 and 62 months. Five-year biochemical failure rate was 3.3% and 4.6%. The 2-fraction cohort had a significantly better mean QOL over time in the bowel domain (p = 0.0004), without a significant difference in the urinary or sexual domains. The 2-fraction cohort had a significantly lower rate of bowel MCIC (17.8% vs 42.3%, p = 0.01), but there was no difference in urinary (24.1% vs 35.7%) or sexual (15.3% vs 29.2%) MCIC. For MCIC x2 (moderate QOL change), the 2-fraction trial had significantly lower MCIC rates in both the bowel (7.1% vs 24%, p = 0.04) and sexual (0 vs 17.6%, p = 0.01) domains.

CONCLUSIONS

2-Fraction SABR is feasible to deliver and well tolerated, with significant signals of improved bowel and sexual QOL. A randomized trial of two vs. five fractions for prostate SABR is needed to confirm the promising findings of this study.

Results of a Prospective Dose Escalation Study of Linear Accelerator-Based Virtual Brachytherapy (BOOSTER) for Prostate Cancer; Virtual HDR Brachytherapy for Prostate Cancer

Purpose

To demonstrate feasibility and toxicity of linear accelerator–based stereotactic radiation therapy boost (SBRT) for prostate cancer, mimicking a high-dose-rate brachytherapy boost.

Methods and Materials

A phase 1 sequential dose escalation study of SBRT compared 20 Gy, 22 Gy, and 24 Gy to the prostate and 25 Gy, 27.5 Gy, and 30 Gy to the gross tumor volume in 2 fractions, combined with 46 Gy in 23 fractions of external beam radiation. Feasibility of dose escalation (volume receiving 125% and 150% of the dose) while meeting organ-at-risk dose constraints, grade 2 acute and late gastrointestinal and genitourinary toxicity, and freedom from biochemical failure were secondary endpoints.

Results

Thirty-six men with intermediate- and high-risk prostate cancer were enrolled with a median follow-up of 24 months. Sixty-four percent of patients had high-risk features. Nine men were enrolled to dose level 1, 6 to level 2, and 6 to level 3. Another 15 patients were treated at dose level 3 on the continuation study. Dose level 3 achieved superior 125% (23.75 Gy) and 150% (28.5 Gy) dose compared to dose levels 1 and 2, with minimal differences in organ-at-risk doses. Kaplan-Meier estimate of freedom from biochemical failure at 3 years was 93.3%. There were no late grade 2 or 3 gastrointestinal events. The late grade 2 genitourinary toxicity at 2 years was 19.3%. Prostate-specific membrane antigen positron emission tomography was performed at 2 years with no local recurrences.

Conclusions

We have shown that a linear accelerator–based SBRT boost for prostate cancer is feasible and can achieve doses comparable to high-dose-rate boost up to the 150% isodose volumes. Rectal, bladder, and urethral doses remained low, and long-term toxicity was the same as or better than previous reports from high-dose-rate or low-dose-rate boost protocols.

Randomised Phase II Feasibility Trial of Image-guided External Beam Radiotherapy With or Without High Dose Rate Brachytherapy Boost in Men with Intermediate-risk Prostate Cancer (CCTG PR15/ NCT01982786)

AIMS

We conducted a multicentre feasibility study to assess the ability to randomise patients between image-guided radiotherapy (IGRT) and IGRT + high dose rate (HDR) brachytherapy boost and to adhere to appropriate radiation quality assurance standards.

MATERIALS AND METHODS

The primary end point was to determine the ability to randomise 60 patients over an 18 month period. Arm 1 (IGRT) patients received 78 Gy in 39 fractions or 60 Gy in 20 fractions (physician's preference), whereas arm 2 (IGRT + HDR) received 37.5 Gy in 15 fractions with HDR boost of 15 Gy. The secondary end points included >grade 3 acute genitourinary and gastrointestinal toxicity, using Common Terminology Criteria for Adverse Events version 4.0 at 3 months, validation of a prospectively defined radiation oncology quality assurance to assess treatment compliance. All analyses were descriptive; no formal comparisons between treatment arms were carried out.

RESULTS

Between April 2014 and September 2015, 57 National Comprehensive Cancer Network (NCCN)-defined intermediate-risk prostate cancer patients were randomised between IGRT alone (arm 1; n = 29) and IGRT plus HDR brachytherapy boost (arm 2; n = 28). Overall, 93% received the treatment as randomised. There were four patients (one on IGRT arm 1 and three patients on the IGRT + HDR arm 2) who were treated differently from randomisation assignment. For the 29 patients receiving IGRT (arm 1), there were 14 cases reported with minor deviations and three with major deviations. For patients on IGRT + HDR (arm 2), there were 18 cases reported with minor deviations and two with major deviations. At 3 months in the IGRT group (arm 1), one patient reported grade 3 diarrhoea, whereas in the IGRT + HDR group (arm 2), two patients reported grade 3 haematuria. No other gastrointestinal and genitourinary toxicities were reported.

CONCLUSION

The pilot study showed the feasibility of randomisation between treatment with IGRT alone versus IGRT + HDR boost. Treatment compliance was good, including adherence to quality assurance standards.

Stereotactic Body Radiotherapy for Primary Prostate Cancer

Prostate cancer is the most common non-cutaneous cancer in males. There are a number of options for patients with localized early stage disease, including active surveillance for low-risk disease, surgery, brachytherapy, and external beam radiotherapy. Increasingly, external beam radiotherapy, in the form of dose-escalated and moderately hypofractionated regimens, is being utilized in prostate cancer, with randomized evidence to support their use. Stereotactic body radiotherapy, which is a form of extreme hypofractionation, delivered with high precision and conformality typically over 1 to 5 fractions, offers a more contemporary approach with several advantages including being non-invasive, cost-effective, convenient for patients, and potentially improving patient access. In fact, one study has estimated that if half of the patients currently eligible for conventional fractionated radiotherapy in the United States were treated instead with stereotactic body radiotherapy, this would result in a total cost savings of US$250 million per year. There is also a strong radiobiological rationale to support its use, with prostate cancer believed to have a low α/β ratio and therefore being preferentially sensitive to larger fraction sizes. To date, there are no published randomized trials reporting on the comparative efficacy of stereotactic body radiotherapy compared to alternative treatment modalities, although multiple randomized trials are currently accruing. Yet, early results from the randomized phase III study of HYPOfractionated RadioTherapy of intermediate risk localized Prostate Cancer (HYPO-RT-PC) trial, as well as multiple single-arm phase I/II trials, indicate low rates of late adverse effects with this approach. In patients with low- to intermediate-risk disease, excellent biochemical relapse-free survival outcomes have been reported, albeit with relatively short median follow-up times. These promising early results, coupled with the enormous potential cost savings and implications for resource availability, suggest that stereotactic body radiotherapy will take center stage in the treatment of prostate cancer in the years to come.

Stereotactic Body Radiotherapy versus Low Dose Rate Brachytherapy for Localised Prostate Cancer: a Cost-Utility Analysis

AIMS

To conduct a cost-utility analysis comparing stereotactic body radiotherapy (SBRT) with low dose rate brachytherapy (LDR-BT) for localised prostate cancer (PCa).

MATERIALS AND METHODS

A decision-analytic Markov model was developed from the healthcare payer perspective to simulate the history of a 66-year-old man with low-risk PCa. The model followed patients yearly over their remaining lifetimes. Health states included 'recurrence-free', 'biochemical recurrence' (BR), 'metastatic' and 'death'. Transition probabilities were based on a retrospective cohort analysis undertaken at our institution. Utilities were derived from the literature. Costs were assigned in 2015 Canadian dollars ($) and reflected Ontario's health system and departmental costs. Outcomes included quality-adjusted life years (QALYs), costs and incremental cost-effectiveness ratios. A willingness-to-pay threshold of $50 000/QALY was used.

RESULTS

SBRT was the dominant strategy with 0.008LYs and 0.029QALYs gained and a reduction in cost of $2615. Under base case conditions, our results were sensitive to the BR probability associated with both strategies. LDR-BT becomes the preferred strategy if the BR with SBRT is 1.3*[baseline BR_SBRT] or if the BR with LDR-BT is 0.76*[baseline BR_LDR-BT]. When assuming the same BR for both strategies, LDR-BT becomes marginally more effective with 0.009QALYs gained at a cost of $272 848/QALY.

CONCLUSIONS

SBRT represents an economically attractive radiation strategy. Further research should be carried out to provide longer-term follow-up and high-quality evidence.

Trends in targeted prostate brachytherapy: from multiparametric MRI to nanomolecular radiosensitizers

The treatment of localized prostate cancer is expected to become a significant problem in the next decade as an increasingly aging population becomes prone to developing the disease. Recent research into the biological nature of prostate cancer has shown that large localized doses of radiation to the cancer offer excellent long-term disease control. Brachytherapy, a form of localized radiation therapy, has been shown to be one of the most effective methods for delivering high radiation doses to the cancer; however, recent evidence suggests that increasing the localized radiation dose without bound may cause unacceptable increases in long-term side effects. This review focuses on methods that have been proposed, or are already in clinical use, to safely escalate the dose of radiation within the prostate. The advent of multiparametric magnetic resonance imaging (mpMRI) to better identify and localize intraprostatic tumors, and nanomolecular radiosensitizers such as gold nanoparticles (GNPs), may be used synergistically to increase doses to cancerous tissue without the requisite hazard of increased side effects.

Targeting tumour hypoxia to improve outcome of stereotactic radiotherapy

BACKGROUND

Hypoxia is a characteristic feature of solid tumours that significantly reduces the efficacy of conventional radiation therapy. In this study we investigated the role of hypoxia in a stereotactic radiation schedule by using a variety of hypoxic modifiers in a preclinical tumour model.

MATERIAL AND METHODS

C3H mammary carcinomas were irradiated with 3 × 15 Gy during a one-week period, followed three days later by a clamped top-up dose to produce a dose response curve; the endpoint was tumour control. The hypoxic modifiers were nimorazole (200 mg/kg), nicotinamide (120 mg/kg) and carbogen (95% O2 + 5% CO2) breathing, OXi4503 (10 mg/kg), and hyperthermia (41.5°C; 1 h).

RESULTS

The radiation dose controlling 50% of clamped tumours (TCD50) following 3 × 15 Gy was 30 Gy. Giving nimorazole or nicotinamide+ carbogen prior to the final 15 Gy fraction non-significantly (χ(2)-test; p < 0.05) reduced this TCD50 to 20-23 Gy; when administered with each 3 × 15 Gy fraction these values were significantly reduced to ≤ 2.5 Gy. Injecting OXi4503 or heating after irradiating significantly reduced the TCD50 to 9-12 Gy regardless of whether administered with one or all three 15 Gy fractions. Combining OXi4503 and heat with the final 15 Gy had a significantly larger effect (TCD50 = 2 Gy).

CONCLUSIONS

Clinically relevant modifiers of hypoxia effectively enhanced an equivalent stereotactic radiation treatment confirming the importance of hypoxia in such schedules.