Pelvic radiotherapy in prostate cancer: an unresolved question

A prospective phase II study of prostate-specific antigen-guided salvage radiotherapy and 68Ga-PSMA-PET for biochemical relapse after radical prostatectomy - The PROPER 1 trial

Background and purpose

The treatment of biochemical recurrence (BCR) after prostatectomy is challenging as the site of the recurrence is often undetectable. Our aim was to test a personalised treatment concept for BCR based on PSA kinetics during salvage radiotherapy (SRT) combined with prostate-specific membrane antigen positron emission tomography (PSMA-PET).

Materials and methods

This phase II trial included 100 patients with BCR. PSMA-PET was performed at baseline. PSA was measured weekly during SRT. Initially, 70 Gy in 35 fractions was prescribed to the prostate bed. Radiotherapy was adapted after 50 Gy. Non-responders (PSA still ≥ 0.15 ng/mL) received sequential lymph node irradiation with a boost to PSMA-PET positive lesions, while responders (PSA < 0.15 ng/mL) continued SRT as planned. PET-findings were only taken into consideration for treatment planning in case of PSA non-response after 50 Gy.

Results

Data from 97 patients were eligible for analysis. Thirty-four patients were classified as responders and 63 as non-responders. PSMA-PET was positive in 3 patients (9%) in the responder group and in 22 (35%) in the non-responder group (p = 0.007). The three-year failure-free survival was 94% for responders and 68% for non-responders (median follow-up 38 months). There were no significant differences in physician-reported urinary and bowel toxicity. Patient-reported diarrhoea at end of SRT was more common among non-responders.

Conclusion

This new personalised treatment concept with intensified SRT based on PSA response demonstrated a high tumour control rate in both responders and non-responders. These results suggest a clinically significant effect with moderate side effects in a patient group with otherwise poor prognosis. PSMA-PET added limited value. The treatment approach is now being evaluated in a phase III trial.Clinical trial registration numbers: NCT02699424&ISRCTN45905321.

Long-Term Results of Moderate Hypofractionation to Prostate and Pelvic Nodes Plus Androgen Suppression in High-Risk Prostate Cancer

PURPOSE

Moderate hypofractionated radiation therapy (HypoRT) is an attractive alternative to conventionally fractionated radiation therapy for prostate cancer. However, most studies using HypoRT only included the prostate as the target volume. We report long-term outcomes of patients with high-risk prostate cancer treated with androgen deprivation therapy (ADT) and HypoRT to the prostate and nodal areas with a simultaneous integrated boost technique.

METHODS AND MATERIALS

Patients with localized, high-risk prostate cancer entered a prospective phase I/II study with a HypoRT regimen of 60 Gy/20 fractions (4 weeks) to the prostate volume while the nodal areas received 44 Gy in the same 20 fractions delivered with intensity modulated radiation therapy with a simultaneous integrated boost technique. ADT started 2 to 3 months before HypoRT. Toxicity was prospectively assessed according to the Common Terminology Criteria for Adverse Events v3. Outcomes rates were calculated by the actuarial method of Kaplan-Meier from the date of last radiation treatment until date of event.

RESULTS

We report on the first 105 patients treated between October 2010 and February 2014. Median follow-up was 74 months, with 97% of patients followed for more than 36 months. Median ADT duration was 18 months. The worst grade 2 or higher late gastrointestinal or genitourinary toxicity was seen in 7% and 9%, respectively. There was no grade 4 or 5 toxicity. At the last follow-up, the rates of grade ≥2 gastrointestinal or genitourinary toxicity were 2% and 3%, respectively, with no residual grade ≥3 toxicity. The 5- and 7-year actuarial overall survival and relapse free survival were 91% and 85% and 87% and 81%, respectively.

CONCLUSIONS

The longest follow-up report of moderate HypoRT (plus ADT) to the prostate and pelvic nodes shows that this approach is feasible, well tolerated, and effective. It is convenient for patients and the health system. A larger randomized trial using this approach is warranted.

Late toxicity and quality of life with prostate only or whole pelvic radiation therapy in high risk prostate cancer (POP-RT): A randomised trial

AIM

To report toxicity and quality of life (QOL) outcomes from a randomised trial of prostate only versus whole pelvic radiotherapy in high risk, node negative prostate cancer.

MATERIALS/METHODS

Patients with localised prostate adenocarcinoma and nodal involvement risk > 20%, were randomised to prostate only (PORT, 68 Gy/25# to prostate) and whole pelvis (WPRT, 68 Gy/25# to prostate and 50 Gy/25# to pelvis) arms with stratification for TURP, Gleason score, baseline PSA, and type of androgen deprivation therapy (ADT). Image guided intensity modulated radiotherapy (IG-IMRT) and two years of ADT were mandatory. Acute and late genitourinary (GU) and gastrointestinal (GI) toxicities were graded using RTOG grading. QOL was assessed using EORTC QLQ-C30 and PR-25 questionnaire pre-treatment and every 3-6 months post RT.

RESULTS

Total 224 patients were randomised (PORT 114, WPRT 110) from November 2011 to August 2017. Median follow up was 44.5 months. No RTOG grade IV toxicity was observed. Acute GI and GU toxicities were similar between both the arms. Cumulative ≥ grade II late GI toxicity was similar for WPRT and PORT (6.5% vs. 3.8%, p = 0.39) but GU toxicity was higher (17.7% vs. 7.5%, p = 0.03). Dosimetric analysis showed higher bladder volume receiving 30-40 Gy in the WPRT arm (V30, 60% vs. 36%, p < 0.001; V40, 41% vs. 25%, p < 0.001). There was no difference in QOL scores of any domain between both arms.

CONCLUSION

Pelvic irradiation using hypofractionated IG-IMRT resulted in increased grade II or higher late genitourinary toxicity as compared to prostate only RT, but the difference was not reflected in patient reported QOL. CLINICALTRIALS.GOV NCT02302105: Prostate Only or Whole Pelvic Radiation Therapy in High Risk Prostate Cancer (POP-RT).

Ten-Year Results From a Phase II Study on Image Guided, Intensity Modulated Radiation Therapy With Simultaneous Integrated Boost in High-Risk Prostate Cancer

Purpose

There is no consensus on how to treat high-risk prostate cancer, and long-term results from hypofractionated radiation therapy are lacking. We report 10-year results after image guided, intensity modulated radiation therapy with hypofractionated simultaneous integrated boost and elective pelvic field.

Methods and Materials

Between 2007 and 2009, 97 consecutive patients with high-risk prostate cancer were included, treated with 2.7 to 2.0 Gy × 25 Gy to the prostate, seminal vesicles, and elective pelvic field. Toxicity was scored according to Radiation Therapy Oncology Group criteria and biochemical disease-free survival (BFS) defined by the Phoenix definition. Patients were subsequently divided into 3 groups: high risk (HR; n = 32), very high risk (VHR; n = 50), and N+/s–prostate-specific antigen (PSA) ≥100 (n = 15). Differences in outcomes were examined using Kaplan-Meier analyses.

Results

BFS in the patients at HR and VHR was 64%, metastasis-free survival 80%, prostate cancer-specific survival 90%, and overall survival (OS) 72%. VHR versus HR subgroups demonstrated significantly different BFS, 54% versus 79% (P = .01). Metastasis-free survival and prostate cancer-specific survival in the VHR group versus HR group were 76% versus 87% (P = .108) and 74% versus 100% (P = .157). Patients reaching nadir PSA <0.1 (n = 80) had significantly better outcomes than the rest (n = 17), with BFS 70% versus 7% (P < .001). Acute grade 2 gastrointestinal tract (GI) and genitourinary tract (GU) toxicity occurred in 27% and 40%, grade 3 GI and GU toxicity in 1% and 3%. Late GI and GU grade 2 toxicity occurred in 1% and 8%.

Conclusions

High-risk prostate cancer patients obtained favorable 10-year outcomes with low toxicity. There were significantly better results in the HR versus the VHR group, both better than the N+/PSA ≥100 group. A nadir PSA value < 0.1 predicted good prognosis.