Prostate irradiation with focal dose escalation to the intraprostatic dominant nodule: a systematic review

Abstract

Radiation therapy (RT) is a curative treatment option for localized prostate cancer. Prostate irradiation with focal dose escalation to the intraprostatic dominant nodule (IDN) is an emerging treatment option that involves the prophylactic irradiation of the whole prostate while increasing RT doses to the visible prostatic tumor. Because of the lack of large multicentre trials, a systematic review was performed in an attempt to get an overview on the feasibility and efficacy of focal dose escalation to the IDN.A bibliographic search for articles in English, which were listed in MEDLINE from 2000 to 2016 to identify publications on RT with focal directed boost to the IDN, was performed. The review was completed following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines.Twenty-two articles describing 1,378 patients treated with RT using focal boost were identified and fulfilled the selection criteria. Intensity-modulated radiation therapy (IMRT) was used in 720 patients (52.3%), volumetric modulated arc therapy was used in 45 patients (3.3%), stereotactic body radiation therapy (SBRT) in 113 patients (8.2%), and low–dose rate and high–dose rate brachytherapy (BT) were used in 305 patients (22.1%) and 195 patients (14.1%), respectively. Use of androgen deprivation therapy varied substantially among series. Biochemical disease-free survival at 5 years was reported for a cohort of 812 (58.9%) patients. The combined median biochemical disease-free survival for this group of patients was 85% (range: 78.8–100%; 95% confidence interval: 77.1–82.7%).The average occurrence of grade III or worse gastrointestinal and genitourinary late toxicity was, respectively, 2.5% and 3.1% for intensity-modulated RT boost, 10% and 6% for stereotactic body RT, 6% and 2% for low–dose rate BT, and 4% and 4.3% for high–dose rate BT.This review shows encouraging results for focal dose escalation to the IDN with acceptable short- to medium-term side effects and biochemical disease control rates. However, owing to the heterogeneity of patient population and the short follow-up, the results should be interpreted with caution. Considering that the clinical endpoint in the studies was biochemical recurrence, the use and duration of androgen deprivation therapy administration should be carefully considered before driving definitive conclusions. Randomized trials with long-term follow-up are needed before this technique can be generally recommended.

50-Gy Stereotactic Body Radiation Therapy to the Dominant Intraprostatic Nodule: Results From a Phase 1a/b Trial

“…7 Despite the strong level-1 scientific evidence supporting the use of ADT with conventional EBRT in intermediate-and high-risk patients, a recent systemic review reported that only 27.8% of the patients treated in the context of prostate dose escalation received ADT. 48 According to the current evidence, it is difficult to rule out that dose escalation to the DIN could provide a benefit for local tumor control in the same magnitude as the addition of ADT. Certainly the lack of use of ADT in our study limits generalizability of our results because according to the standard approach, these patients should have all received ADT.…”

“…Mature prostate SBRT trials have been summarized in a recent review. 48 7 Katz reported 10-year biochemical control of 93% for low-risk patients who received 35 to 36.25 Gy in 5 daily fractions. 49 A Canadian trial recently reported 5-year biochemical control rate of 97% in patients at low-to intermediate risk who were treated with 40 Gy in 5 fractions delivered over 29 days (once-a-week treatment).…”

Stereotactic radiotherapy with focal boost for intermediate and high-risk prostate cancer: Initial results of the SPARC trial

“…A systematic review of 2036 prostate SABR patients showed pooled late grade 3+ GU and GI toxicity to be 2% and 1% respectively [23] . Studies incorporating a DIL boost report slightly higher grade 3+ toxicity; between 2 and 6% for IMRT and brachytherapy boost techniques, and up to 10% for SABR boosts [8] but long term follow up is lacking.…”

“…Evidence to support dose escalation to the DIL is increasing, with the hypo-FLAME trial recently reporting favourable results [22] . A recent systematic review identified 22 trials of prostate radiation therapy with focal dose escalation to the intraprostatic dominant nodule [8] , a term used interchangeably with DIL. Biochemical control was achieved in 80–100% of cases.…”

“…As this nodule often exhibits the most aggressive biological behaviour in multifocal disease, it can dictate the overall clinical prognosis [7] . Data supporting dose escalation to the DIL is growing in both external beam and brachytherapy literature [8] , with randomised studies currently underway.…”