Long-Term Outcomes of Dose-Escalated Pelvic Lymph Node Intensity-Modulated Radiation Therapy (IMRT) With a Simultaneous Hypofractionated Boost to the Prostate for Very High-Risk Adenocarcinoma of the Prostate: A Prospective Phase II Clinical Trial

PURPOSE

There remains limited data as to the feasibility, safety, and efficacy of higher doses of elective radiation therapy to the pelvic lymph nodes in men with high-risk prostate cancer. We conducted a phase II study to evaluate moderate dose escalation to the pelvic lymph nodes using a simultaneous integrated boost to the prostate.

METHODS AND MATERIALS

Patients were eligible with biopsy-proven adenocarcinoma of the prostate, a calculated lymph node risk of at least 25%, Karnofsky performance scale ≥70, and no evidence of M1 disease. Acute and late toxicity were prospectively collected at each follow-up using Common Terminology Criteria for Adverse Events version 4.0 (CTCAE v4.0). The pelvic lymph nodes were treated to a dose of 56 Gy over 28 fractions with a simultaneous integrated boost to the prostate to a total dose of 70 Gy over 28 fractions using intensity-modulated radiation therapy.

RESULTS

Thirty patients were prospectively enrolled from October 2010 to August 2014. Median patient age was 70 years (57-83), pretreatment prostate-specific antigen was 11.5 ng/mL (3.23-111.5), T stage was T2c (T1c-T3b), and Gleason score was 9 (6-9). CTCAE v4.0 rate of any grade 1 or 2 genitourinary and gastrointestinal toxicity were 55% and 44%, respectively, and there was 1 reported acute grade 3 genitourinary and gastrointestinal toxicity, both unrelated to protocol therapy. With a median follow-up of 6.4 years, the biochemical failure free survival rate was 80.2%, and mean biochemical progression free survival was 8.3 years (95% confidence interval [CI], 7.2-9.4). The prostate cancer specific survival was 95.2%, and mean prostate cancer specific survival was 8.7 years (95% CI, 8.0-9.4). Five-year distant metastases free survival was 96%. Medians were not reached.

CONCLUSIONS

In this single arm, small, prospective feasibility study, nodal radiation therapy dose escalation was safe, feasible, and seemingly well tolerated. Rates of progression free survival are highly encouraging in this population of predominately National Comprehensive Cancer Network very high-risk patients.

Comparative Effectiveness of Different Radical Radiotherapy Treatment Regimens for Prostate Cancer: A Population-Based Cohort Study

Background

It is unclear which radiotherapy technique and dose fractionation scheme is most effective in decreasing the risk of prostate cancer death.

Methods

We conducted a population-based cohort study among 15 164 men in the Prostate Cancer database Sweden (version 4.0) treated with primary radical radiotherapy for prostate cancer in Sweden from 1998 to 2016. We calculated hazard ratios with 95% confidence intervals (CIs) of the association between the following exposure groups and outcome: conventionally fractionated external beam radiotherapy (EBRT) to 78 Gy (39 × 2 Gy), EBRT combined with high dose-rate brachytherapy (HDR-BT) (25 × 2 Gy + 2 × 10 Gy), conventionally fractionated EBRT to 70 Gy (35 × 2 Gy), and moderately hypofractionated (M-HF) dose-escalated EBRT (29 × 2.5 Gy or 22 × 3 Gy).

Results

Of the men, 7296 received conventionally fractionated EBRT to 78 Gy, 4657 EBRT combined with HDR-BT, 1672 conventionally fractionated EBRT to 70 Gy, and 1539 M-HF EBRT. Using EBRT to 78 Gy as the reference, the multivariable hazard ratios (95% CIs) of prostate cancer death was 0.64 (0.53 to 0.78) for EBRT combined with HDR-BT, 1.00 (0.80 to 1.27) for EBRT to 70 Gy, and 1.51 (0.99 to 2.32) for M-HF EBRT. The multivariable hazard ratios (95% CIs) for death from any cause were 0.79 (0.71 to 0.88), 0.99 (0.87 to 1.14), and 1.12 (0.88 to 1.42), respectively. The lower risk of prostate cancer death comparing EBRT combined with HDR-BT with conventionally fractionated EBRT to 78 Gy was more pronounced for men with high-risk or poorly differentiated tumors.

Conclusions

In this study, EBRT combined with HDR-BT was the most effective radiotherapy treatment regimen, especially for poorly differentiated tumors. Randomized trials comparing EBRT combined with HDR-BT with dose-escalated EBRT should be a priority.

Ultra-hypofractionated radiation therapy for unfavourable intermediate-risk and high-risk prostate cancer is safe and effective: 5-year outcomes of a phase II trial

OBJECTIVES

To report toxicity (primary endpoint) and biochemical disease-free survival (BDFS) outcomes of a phase II trial evaluating ultra-hypofractionated radiation therapy (UHRT), focusing on patients with unfavourable intermediate-risk and high-risk prostate cancer (PCa).

PATIENTS AND METHODS

From 2012 to 2017, 154 patients (92 with unfavourable intermediate-risk or high-risk PCa) were treated with helical TomoTherapy delivering 43.8-45.2 Gy in eight fractions over 3 weeks. Of these, 73% received hormonotherapy (51% neoadjuvant).

RESULTS

The median (range) follow-up was 48 (19-84) months. For the whole series, crude BDFS and 5-year BDFS rates were 97.4% and 94.3%, respectively. The corresponding figures for unfavourable intermediate-risk and high-risk PCa were 96.7% and 90%, respectively. The crude metastasis-free survival rate was 98% for the unfavourable intermediate-risk and high-risk group. For the whole series, the 5-year cumulative urinary/intestinal grade 2+ late toxicity was 17.8/7.4%. No grade 4-5 toxicity was observed. One patient experienced late grade 3 toxicity (urinary).

CONCLUSION

This eight-fraction UHRT regimen can be safely delivered to patients with unfavourable intermediate-risk/high-risk PCa. Its relapse rates are similar to those reported for the combination of external beam radiotherapy plus brachytherapy, however, the observed toxicity profile is milder. The disease survival rates compare favourably with historical controls in some other forms of radiotherapy, with similar side effects. Since the low rate of biochemical/metastasis relapse is encouraging, further research to confirm these results is justified.

Prostate brachytherapy procedural training: incorporation of related procedures in resident training and competency assessment

Purpose

Inadequate procedural training is of increasing concern in resident training, especially in prostate brachytherapy (PB). Transperineal rectal spacer placement (TRSP) requires many of the same proficiencies as PB. This work describes the assessment of teaching techniques focusing on developing critical competencies for PB using related clinical procedures (TRSP).

Material and methods

For PB and TRSP, key competencies were identified: 9 for PB and 7 for TRSP; 4 are shared between PB and TRSP. "Comfort level" with these procedures was assessed prior to and following participation in TRSP.

Results

8 of 12 trainees at our institution participated in TRSP procedures. 2 of these trainees had prior experience with PB or related procedures and were excluded. Trainees self-reported "comfort levels" between 0 and 3 for four competency domains. Initial median comfort (MC) level for competency domains relevant to PB included: patient positioning (median 1, range 0-2), transrectal ultrasound imaging (median 1, range 0-1), fiducial placement (median 1, range 0-1), and hydrodissection (median 0, range 0-1). Median number of TRSP procedures performed by assessed trainees during the analysis period was 4 (range 1-6). Following TRSP procedure training, MC level increased: 2 points for patient positioning (median 3, range 1-3; p < 0.01), 1.5 points for transrectal ultrasound imaging (median 2.5, range 1.3, p < 0.001); 1 point for fiducial placement (median score 2, range 1-3; p < 0.001); and 1.5 points for hydrodissection (median score 2, range 1-3; p < 0.001).

Conclusions

Increasing trainee involvement in related procedures to develop core competencies may help facilitate increased comfort with common skills critical to the independent performance of PB.

The current state of randomized clinical trial evidence for prostate brachytherapy

Interstitial brachytherapy is one of several curative therapeutic options for the treatment of localized prostate cancer. In this review, we summarize all available randomized data to support the optimal use of prostate brachytherapy. Evidence from completed randomized controlled trials is the focus of this review with a presentation also of important ongoing trials. Gaps in knowledge are identified where future investigation may be fruitful with intent to inspire well-designed prospective studies with standardized treatment that focuses on improving oncological outcomes, reducing morbidity, or maintaining quality of life.

Correlation between real-time intraoperative and postoperative dosimetry and its implications on intraoperative planning

PURPOSE

The purpose of this study was to study the correlation between intraoperative and postimplant dosimetry. We investigated the correlation between prostate (V₁₅₀) and urethra (D₃₀, D₅) dose limits, and whether it is possible to increase prostate D₉₀ and V₁₀₀ in intraoperative planning without violating postimplant urethra and rectum dose limits.

METHODS AND MATERIALS

Seventy-nine patients who underwent real-time ultrasound-guided prostate implants using intraoperative planning from 2013 to 2017 were analyzed. Forty-one of the 79 implants were ¹²⁵I as monotherapy and the remainder was ¹⁰³Pd as boost to external beam radiation therapy or external beam radiation therapy plus androgen deprivation therapy. Prescriptions followed the guidelines of AAPM TG-137. The urethra was catheterized during intraoperative implantation and postimplant imaging to facilitate the urethra identification. T2-cubed MRI and CT were acquired on the same day and about 1 month after the low-dose-rate procedure, and MRI was later fused with the CT scan for accurate delineation of the prostate and postimplant dosimetry evaluation. An institutionally based peer-review process and document procedure were established based on national recommendations. Correlation of dose parameters: D₉₀, V₁₅₀, V₁₀₀ of prostate, D₃₀, D₅ of urethra, and V₁₀₀ of rectum between intraoperative and postimplant plans were evaluated.

RESULTS

D₉₀ and V₁₀₀ declined for all implants between intraoperative and postimplant dosimetry. On average, D₉₀ declined by 17.5% and 21.7% for ¹²⁵I and ¹⁰³Pb implants, respectively. V₁₀₀ declined for all implants between intraoperative and postimplant dosimetry but less pronounced. Prostate V₁₅₀ and urethra D₃₀ and D₅ also showed different tendency of decline. Of the 79 implants, 60 did not meet the postimplant dosimetry target for prostate (V₁₅₀ ≤ 50%), and 46 of the 60 implants met the optimal dosimetry targets for both D₃₀ (<125%) and D₅ (<150%), and the other 14 of the 60 implants failed to meet either the D₃₀ or the D₅ limits. All the implants met the postimplant target dose for rectum: V₁₀₀≤ 1.3 cc.

CONCLUSION

Intraoperative implant dosimetry could not accurately predict postimplant dosimetry; however, to avoid underdosage of prostate, intraoperative D₉₀ should be close to 120% of prescribed dose and V₁₀₀ needs to be close to 100% of prescribed dose. Prostate V₁₅₀> 50% does not necessarily indicate the violation of urethra D₃₀ and D₅ dose limits. For most of the implants, target intraoperative D₉₀ and V₁₀₀ could be raised without violating urethra D₃₀ and D₅ limits recommended by American Brachytherapy Society in postimplant evaluation.