Updated results of high-dose rate brachytherapy and external beam radiotherapy for locally and locally advanced prostate cancer using the RTOG-ASTRO Phoenix definition

A comparative study of high-dose-rate brachytherapy boost combined with external beam radiation therapy versus external beam radiation therapy alone for high-risk prostate cancer

We aimed to compare the outcomes of high-dose-rate brachytherapy (HDR-BT) boost and external beam radiation therapy (EBRT) alone for high-risk prostate cancer. This was a single-center, retrospective and observational study. Consecutive patients who underwent initial radical treatment by HDR-BT boost or EBRT alone from June 2009 to May 2016 at the Niigata University Medical and Dental Hospital, Japan were included. A total of 96 patients underwent HDR-BT boost, and 61 underwent EBRT alone. The prescription dose of HDR-BT boost was set to 18 Gy twice a day with EBRT 39 Gy/13 fractions. The dose for EBRT alone was mostly 70 Gy/28 fractions. The high-risk group received >6 months of prior androgen deprivation therapy. Overall survival, biochemical-free survival, local control and distant metastasis-free survival rates at 5 years were analyzed. The incidence of urological and gastrointestinal late adverse events of Grade 2 and above was also summarized. In the National Comprehensive Cancer Network (NCCN) high-risk calssification, HDR-BT boost had a significantly higher biochemical-free survival rate at 5 years (98.9% versus 90.7%, P = 0.04). Urethral strictures were more common in the HDR-BT boost group. We will continuously observe the progress of the study patients and determine the longer term results.

Brachytherapy boost (BT-boost) or stereotactic body radiation therapy boost (SBRT-boost) for high-risk prostate cancer (HR-PCa)

Systematic review for the treatment of high-risk prostate cancer (HR-PCa, D'Amico classification risk system) with external body radiation therapy (EBRT)+brachytherapy-boost (BT-boost) or with EBRT+stereotactic body RT-boost (SBRT-boost). In March 2020, 391 English citations on PubMed matched with search terms "high risk prostate cancer boost". Respectively 9 and 48 prospective and retrospective studies were on BT-boost and 7 retrospective studies were on SBRT-boost. Two SBRT-boost trials were prospective. Only one study (ASCENDE-RT) directly compared the gold standard treatment [dose-escalation (DE)-EBRT+androgen deprivation treatment (ADT)] versus EBRT+ADT+BT-boost. Biochemical control rates at 9 years were 83% in the experimental arm versus 63% in the standard arm. Cumulative incidence of late grade 3 urinary toxicity in the experimental arm and in the standard arm was respectively 18% and 5%. Two recent studies with HR-PCa (National Cancer Database) demonstrated better overall survival with BT-boost (low dose rate LDR or high dose rate HDR) compared with DE-EBRT. These recent findings demonstrate the superiority of EBRT+BT-boost+ADT versus DE-EBRT+ADT for HR-PCa. It seems that EBRT+BT-boost+ADT could now be considered as a gold standard treatment for HR-PCa. HDR or LDR are options. SBRT-boost represents an attractive alternative, but the absence of randomised trials does not allow us to conclude for HR-PCa. Prospective randomised international phase III trials or meta-analyses could improve the level of evidence of SBRT-boost for HR-PCa.

Building a High-Dose-Rate Prostate Brachytherapy Program With Real-Time Ultrasound-Based Planning: Initial Safety, Quality, and Outcome Results

Purpose

Growing evidence supports the efficacy and safety of high-dose-rate (HDR) brachytherapy as a boost or monotherapy in prostate cancer treatment. We initiated a new HDR prostate brachytherapy practice in April 2014. Here, we report the learning experiences, short-term safety, quality, and outcome.

Methods and Materials

From April 2014 to December 2017, 164 men were treated with HDR brachytherapy with curative intent. Twenty-eight men (17.1%) underwent HDR brachytherapy as monotherapy, receiving 25 to 27 Gy in 2 fractions. Men treated with HDR brachytherapy as a boost received 19 to 21 Gy in 2 fractions. Fifty-two men (31.7%) had high-risk disease. HDR procedure times, dosimetry, and response were recorded and analyzed. Genitourinary (GU) and gastrointestinal (GI) toxicities were recorded according to the toxicity criteria of the Radiation Therapy Oncology Group.

Results

Mean HDR procedure times decreased yearly from 179 minutes in 2014 to 115 minutes in 2017. Median follow-up was 18.6 months (range, 3-55 months). At last review, 79% of patients reported returning to baseline GU status, and 100% of patients noted no change in GI status from their baseline. Four patients experienced acute urinary retention. Treatment planning target volume (PTV) was defined as prostate with margins. Dosimetrically, 97.5% of all HDR implants had PTV D90 ≥100%, 81.5% had PTV V100 ≥95%, 73.6% had maximal urethral doses ≤120%, and 77.5% had rectal 1 mL dose ≤70% (all but one ≤10.8 Gy). The estimated 3-year overall survival was 98.7% (95% confidence interval, 91.4%-99.8%), and disease-free survival was 96.2% (95% confidence interval, 89.5%-98.7%).

Conclusions

The low incidence of GU and GI complications in our cohort demonstrates that a HDR brachytherapy program can be successfully developed as a treatment option for patients with localized prostate cancer.

High dose-rate brachytherapy in the treatment of prostate cancer

High dose-rate (HDR) brachytherapy involves delivery of a high dose of radiation to the cancer with great sparing of surrounding organs at risk. Prostate cancer is thought to be particularly sensitive to radiation delivered at high dose-rate or at high dose per fraction. The rapid delivery and high conformality of dose results in lower toxicity than that seen with low dose-rate (LDR) implants. HDR combined with external beam radiotherapy results in higher cancer control rate than external beam only, and should be offered to eligible high and intermediate risk patients. While a variety of dose and fractionations have been used, a single 15 Gy HDR combined with 40-50 Gy external beam radiotherapy results in a disease-free survival of over 90% for intermediate risk and 80% for high risk. HDR monotherapy in two or more fractions (e.g., 27 Gy in 2 fractions or 34.5 Gy in 3) is emerging as a viable alternative to LDR brachytherapy for low and low-intermediate risk patients, and has less toxicity. The role of single fraction monotherapy to a dose of 19-20 Gy is evolving, with some conflicting data to date. HDR should also be considered as a salvage approach for recurrent disease following previous external beam radiotherapy. A particular advantage of HDR in this setting is the ease of delivering focal treatments, which combined with modern imaging allows focal dose escalation with minimal toxicity. Trans-rectal ultrasound (TRUS) based planning is replacing CT-based planning as the technique of choice as it minimizes or eliminates the need to move the patient between insertion, planning and treatment delivery, thus ensuring high accuracy and reproducibility of treatment.

High-dose-rate brachytherapy boost for prostate cancer: rationale and technique

High-dose-rate brachytherapy (HDR) is a method of conformal dose escalation to the prostate. It can be used as a local boost in combination with external beam radiotherapy, with a high degree of efficacy and low rate of long term toxicity. Data consistently reports relapse free survival rates of greater than 90% for intermediate risk patients and greater than 80% for high risk. Results are superior to those achieved with external beam radiotherapy alone. A wide range of dose and fractionation is reported, however, we have found that a single 15 Gy HDR combined with hypofractionated radiotherapy to a dose of 37.5 Gy in 15 fractions is well tolerated and is associated with a long term relapse-free survival of over 90%. Either CT-based or trans-rectal ultrasound-based planning may be used. The latter enables treatment delivery without having to move the patient with risk of catheter displacement. We have found it to be an efficient and quick method of treatment, allowing catheter insertion, planning, and treatment delivery to be completed in less than 90 minutes. High-dose-rate boost should be considered the treatment of choice for many men with high and intermediate risk prostate cancer.

High-dose-rate brachytherapy and hypofractionated external beam radiotherapy combined with long-term hormonal therapy for high-risk and very high-risk prostate cancer: outcomes after 5-year follow-up

The purpose of this study was to report the outcomes of high-dose-rate (HDR) brachytherapy and hypofractionated external beam radiotherapy (EBRT) combined with long-term androgen deprivation therapy (ADT) for National Comprehensive Cancer Network (NCCN) criteria-defined high-risk (HR) and very high-risk (VHR) prostate cancer. Data from 178 HR (n = 96, 54%) and VHR (n = 82, 46%) prostate cancer patients who underwent (192)Ir-HDR brachytherapy and hypofractionated EBRT with long-term ADT between 2003 and 2008 were retrospectively analyzed. The mean dose to 90% of the planning target volume was 6.3 Gy/fraction of HDR brachytherapy. After five fractions of HDR treatment, EBRT with 10 fractions of 3 Gy was administered. All patients initially underwent ≥ 6 months of neoadjuvant ADT, and adjuvant ADT was continued for 36 months after EBRT. The median follow-up was 61 months (range, 25-94 months) from the start of radiotherapy. The 5-year biochemical non-evidence of disease, freedom from clinical failure and overall survival rates were 90.6% (HR, 97.8%; VHR, 81.9%), 95.2% (HR, 97.7%; VHR, 92.1%), and 96.9% (HR, 100%; VHR, 93.3%), respectively. The highest Radiation Therapy Oncology Group-defined late genitourinary toxicities were Grade 2 in 7.3% of patients and Grade 3 in 9.6%. The highest late gastrointestinal toxicities were Grade 2 in 2.8% of patients and Grade 3 in 0%. Although the 5-year outcome of this tri-modality approach seems favorable, further follow-up is necessary to validate clinical and survival advantages of this intensive approach compared with the standard EBRT approach.

External-beam radiation therapy and high-dose rate brachytherapy combined with long-term androgen deprivation therapy in high and very high prostate cancer: preliminary data on clinical outcome

PURPOSE

To determine the feasibility of combined long-term androgen deprivation therapy (ADT) and dose escalation with high-dose-rate (HDR) brachytherapy.

METHODS AND MATERIALS

Between 2001 and 2007, 200 patients with high-risk prostate cancer (32.5%) or very high-risk prostate cancer (67.5%) were prospectively enrolled in this Phase II trial. Tumor characteristics included a median pretreatment prostate-specific antigen of 15.2 ng/mL, a clinical stage of T2c, and a Gleason score of 7. Treatment consisted of 54 Gy of external irradiation (three-dimensional conformal radiotherapy [3DCRT]) followed by 19 Gy of HDR brachytherapy in four twice-daily treatments. ADT started 0-3 months before 3DCRT and continued for 2 years.

RESULTS

One hundred and ninety patients (95%) received 2 years of ADT. After a median follow-up of 3.7 years (range, 2-9), late Grade ≥2 urinary toxicity was observed in 18% of the patients and Grade ≥3 was observed in 5%. Prior transurethral resection of the prostate (p = 0.013) and bladder D(50) ≥1.19 Gy (p = 0.014) were associated with increased Grade ≥2 urinary complications; age ≥70 (p = 0.05) was associated with Grade ≥3 urinary complications. Late Grade ≥2 gastrointestinal toxicity was observed in 9% of the patients and Grade ≥3 in 1.5%. CTV size ≥35.8 cc (p = 0.007) and D(100) ≥3.05 Gy (p = 0.01) were significant for increased Grade ≥2 complications. The 5-year and 9-year biochemical relapse-free survival (nadir + 2) rates were 85.1% and 75.7%, respectively. Patients with Gleason score of 7-10 had a decreased biochemical relapse-free survival (p = 0.007).

CONCLUSIONS

Intermediate-term results at the 5-year time point indicate a favorable outcome without an increase in the rate of late complications.

Moderate dose escalation with single-fraction high-dose-rate brachytherapy boost for clinically localized intermediate- and high-risk prostate cancer: 5-year outcome of the first 100 consecutively treated patients

PURPOSE

To analyze the clinical outcome and toxicity data of the first 100 consecutive patients treated with a single-fraction high-dose-rate brachytherapy (HDR-BT) and external beam radiotherapy (EBRT).

METHODS AND MATERIALS

Two-hundred eighty patients have been treated with HDR-BT boost for localized intermediate- to high-risk prostate cancer. Among these, the outcome and toxicity of the first 100 patients treated with a single HDR-BT fraction were assessed. A median dose of 60Gy EBRT was given to the prostate and vesicles. Interstitial HDR-BT of 10Gy was performed during the course of EBRT.

RESULTS

Median followup time was 61.5 months. The 5-year actuarial rates of overall survival, cause-specific survival, disease-free survival, and biochemical no evidence of disease (bNED) for the entire cohort were 93.3%, 99.0%, 89.3%, and 85.5%, respectively. The 7-year actuarial rate of bNED was 84.2% for the intermediate-risk group and 81.6% for the high-risk group (p=0.8464). The 7-year actuarial rates of bNED for Grade 1, 2, and 3 tumors were 97.5%, 80.0%, and 67.1%, respectively. The 5-year probability for developing late Grade 3 gastrointestinal and genitourinary (GU) toxicity was 2.1% and 14.4%, respectively. Grade 3 GU complications occurred significantly more frequently in patients with a history of preirradiation transurethral resection (29.1% vs. 8.8%; p=0.0047).

CONCLUSIONS

Five-year outcome after 60Gy EBRT plus a single fraction of 10Gy HDR-BT boost is encouraging. Preradiation transurethral resection significantly increases the risk of late severe GU complications.