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Article of the month: Long‐term oncological and functional follow‐up in low‐dose‐rate brachytherapy for PCa: results from the prospective nationwide Swiss registry

Every month, the Editor-in-Chief selects an Article of the Month from the current issue of BJUI. The abstract is reproduced below and you can click on the button to read the full article, which is freely available to all readers for at least 30 days from the time of this post.

In addition to this post there is also an Editorial written by a prominent member of the urological community and a visual abstract created by Cora Griffin at King’s College London. We invite you to use the comment tools at the bottom of each post to join the conversation. 

If you only have time to read one article this month, we recommend this one. 

Long‐term oncological and functional follow‐up in low‐dose‐rate brachytherapy for prostate cancer: results from the prospective nationwide Swiss registry

Pascal Viktorin-Baier*, Paul M. Putora‡§, Hans-Peter Schmid*, Ludwig Plasswilm‡§, Christoph Schwab*, Armin Thoeni, Werner Hochreiter**, Ladislav Prikler††, Stefan Suter‡‡, Patrick Stucki, Michael Müntener§§, Nadja Blick§§, Hans Schiefer, Sabine Güsewell¶¶, Karin Zürn* and Daniel Engeler*

*Department of Urology, St. Gallen Cantonal Hospital, St. Gallen, Urology Clinic, Cantonal Hospital Lucerne, Lucerne, Department of Radiation Oncology, St. Gallen Cantonal Hospital, St. Gallen, §Department of Radiation Oncology, University of Berne, Clinic for Radiation-Oncology, Lindenhof Hospital Berne, Berne, **Urology Clinic, Hirslanden Clinic Aarau, Aarau, ††Urology Clinic, Uroviva Clinic Buelach, Buelach, ‡‡Urology Clinic Zug, Zug, §§Urology Clinic, Triemli Hospital, Zurich, and ¶¶Clinical Trial Unit, St. Gallen Cantonal Hospital, St. Gallen, Switzerland

Abstract

Objective

To evaluate the long‐term oncological, functional and toxicity outcomes of low‐dose‐rate brachytherapy (LDR‐BT) in relation to risk factors and radiation dose in a prospective multicentre cohort.

Patients and Methods

Data of patients from 12 Swiss centres undergoing LDR‐BT from September 2004 to March 2018 were prospectively collected. Patients with a follow‐up of ≥3 months were analysed. Functional and oncological outcomes were assessed at ~6 weeks, 6 and 12 months after implantation and annually thereafter. LDR‐BT was performed with 125I seeds. Dosimetry was done 6 weeks after implantation based on the European Society for Radiotherapy and Oncology recommendations. The Kaplan–Meier method was used for biochemical recurrence‐free survival (BRFS). A prostate‐specific antigen (PSA) rise above the PSA nadir + 2 was defined as biochemical failure. Functional outcomes were assessed by urodynamic measurement parameters and questionnaires.

Results

Of 1580 patients in the database, 1291 (81.7%) were evaluable for therapy outcome. The median (range) follow‐up was 37.1 (3.0–141.6) months. Better BRFS was found for Gleason score ≤3+4 ( = 0.03, log‐rank test) and initial PSA level of <10 ng/mL ( < 0.001). D’Amico Risk groups were significantly associated with BRFS ( < 0.001), with a hazard ratio of 2.38 for intermediate‐ and high‐risk patients vs low‐risk patients. The radiation dose covering 90% of the prostate volume (D90) after 6 weeks was significantly lower in patients with recurrence. Functional outcomes returned close to baseline levels after 2–3 years. A major limitation of these findings is a substantial loss to follow‐up.

Conclusion

Our results are in line with other studies showing that LDR‐BT is associated with good oncological outcomes together with good functional results.

Editorial: Low-dose-rate brachytherapy for prostate cancer stands the test of time – the Swiss experience

The clinical results from 12 Swiss centres reaffirm the benefits of Low Dose Rate Brachytherapy (LDR-BT) for the treatment of localised prostate cancer [1]. The authors are to be commended for collating and analysing prospective, countrywide, long-term data. This is an excellent example of Good Clinical Practice for the urology community, patients, commissioning groups and for governance purposes. Prostate brachytherapy offers suitable men with prostate cancer a high chance of long-term cure but with a low risk of urinary incontinence and most retaining erectile dysfunction [2].

Two thirds of the patients reported in the Swiss series had low-risk cancer who would now more commonly be offered active surveillance as an initial treatment option. However our own and other large mature series have shown similar treatment efficacy of LDR-BT, either as monotherapy as in the Swiss study, or as a boost to external-beam radiotherapy, for the treatment of patients with intermediate and high risk of disease relapse [3, 4]. Indeed the ASCENDE-RT trial recently showed that men with unfavourable intermediate or high-risk prostate cancer randomised to an LDR-BT boost arm, relative to a dose-escalated external-beam radiotherapy boost, were twice as likely to be free of biochemical failure at a median follow-up of 6.5 years. A slight increase in urinary toxicity was observed which may have been an issue related to implant technique [5].

The authors show LDR-BT affords excellent disease control that associates with post-implant dosimetry in keeping with current treatment guidelines. They also report an association between biochemical control and seed loss. It therefore becomes unclear the extent to which implant quality or implant technique, i.e. the use of loose or stranded seeds, influenced the oncological outcome, as it would appear that more than one brachytherapy technique has been used.

In this series no prostate cancer-related deaths were reported. However the median follow-up length of 37 months is relatively short. Examples from more mature series show longer follow-up is needed to begin to document the low rates of prostate cancer-related deaths following LDR-BT. Lazarev et al [6] in a similar risk group distribution to the Swiss population, reported 97% prostate cancer-specific survival at 17-years with all deaths occurring more than 10 years after treatment. Morris et al [4] reported 99.1% cause-specific survival at 10 years with death events 9 years after treatment in low and intermediate-risk disease. Our own series showed 98% prostate-cancer-specific survival at 7 and 9 years post-implantation in high-risk (as defined by NICE) patients treated with monotherapy [3].

Treatment-related toxicity assessments in the Swiss series showed that baseline values are crucial to understand the impact of treatment on patient-reported outcomes. Higher post-implant scores were consistently observed in those patients with higher baseline scores. The patient-reported outcomes were similar to those from our series where sexual potency was preserved in 70-80% of men who were ≤60 years old at time of implant [7].

Salvage therapies are seldom given after LDR-BT as the local failure rate is low and the surgery complex. It was undertaken in only two patients in the Swiss series. In the era of mp-MRI and PSMA PET/CT scans and targeted biopsies, tumour recurrence can be better assessed.  Salvage surgery has been offered to approximately 0.5% (27/4200) of our patients, by either robotic-assisted radical prostatectomy or seminal vesiculectomy if the recurrence is localised to the seminal vesicle alone.

This nation-wide report from the 12 Swiss centres is a welcome addition to the extensive body of evidence that attests to the excellent results and generalisability of prostate LDR-BT. The treatment is efficacious and convenient for patients with a low toxicity profile. It is a cost effective option that should be offered to all suitable patients with localised prostate cancer.

by Stephen Langley

References

1. Viktorin-Baier P, Putora PM, Schmid HP, et al. Long-term oncological and functional follow-up in low-dose-rate brachytherapy for prostate cancer: results from the prospective nationwide Swiss registry. BJU Int 2020: 125(6).

2. Punnen S, Cowan JE, Chan JM, Carroll PR, Cooperberg MR. Long-term health-related quality of life after primary treatment for localized prostate cancer: results from the CaPSURE registry. European urology 2015; 68: 600-608.

3. Laing R, Uribe J, Uribe-Lewis S, et al. Low-dose-rate brachytherapy for the treatment of localised prostate cancer in men with a high risk of disease relapse. BJU Int 2018; 122: 610-617.

4. Morris WJ, Keyes M, Spadinger I, et al. Population-based 10-year oncologic outcomes after low-dose-rate brachytherapy for low-risk and intermediate-risk prostate cancer. Cancer 2013; 119: 1537-1546.

5. Morris WJ, Tyldesley S, Rodda S, et al. Androgen Suppression Combined with Elective Nodal and Dose Escalated Radiation Therapy (the ASCENDE-RT Trial): An Analysis of Survival Endpoints for a Randomized Trial Comparing a Low-Dose-Rate Brachytherapy Boost to a Dose-Escalated External Beam Boost for High- and Intermediate-risk Prostate Cancer. Int J Rad Onc Bio Phys 2017; 98: 275-285.

6. Lazarev S, Thompson MR, Stone NN, Stock RG. Low-dose-rate brachytherapy for prostate cancer: outcomes at >10 years of follow-up. BJU Int 2018; 121: 781-790.

7. Langley SEM, Soares R, Uribe J, et al. Long-term oncological outcomes and toxicity in 597 men aged ≤60 years at time of low-dose-rate brachytherapy for localised prostate cancer. BJU Int 2018; 121: 38-45.

Article of the Week: Oncological outcomes and toxicity for LDR prostate brachytherapy

Every Week the Editor-in-Chief selects an Article of the Week from the current issue of BJUI. The abstract is reproduced below and you can click on the button to read the full article, which is freely available to all readers for at least 30 days from the time of this post.

In addition to the article itself, there is an accompanying editorial written by a prominent member of the urological community. This blog is intended to provoke comment and discussion and we invite you to use the comment tools at the bottom of each post to join the conversation.

If you only have time to read one article this week, it should be this one.

Long-term oncological outcomes and toxicity in 597 men aged ≤60 years at time of low-dose-rate brachytherapy for localised prostate cancer

Stephen E. M. Langley, Ricardo Soares, Jennifer Uribe, Santiago Uribe-LewisJulian Money-Kyrle, Carla Perna, Sara Khaksar and Robert Laing

 

St Lukes Cancer Centre, Guildford, Surrey, UK

 

Objectives

To report oncological and functional outcomes of men treated with low-dose-rate (LDR) prostate brachytherapy aged ≤60 years at time of treatment.

Patients and Methods

Of 3262 patients treated with LDR brachytherapy at our centre up to June 2016, we retrospectively identified 597 patients aged ≤60 years at treatment with ≥3-years post-implantation follow-up and four prostate-specific antigen (PSA) measurements, of which one was at baseline. Overall survival (OS), prostate cancer-specific survival (PCSS) and relapse free survival (RFS) were analysed together with prospectively collected physician-reported adverse events and patient-reported symptom scores.

Results

The median (range) age was 57 (44-60) years, follow-up was 8.9 (1.5-17.2) years, and PSA follow-up 5.9 (0.8-15) years. Low-, intermediate- and high-risk disease represented 53%, 37% and 10% of the patients, respectively. At 10 years after implantation OS and PCSS were 98% and 99% for low-risk, 99% and 100% for intermediate-risk, and 93% and 95% for high-risk disease, respectively. At 10 years after implantation RFS, using the PSA level nadir plus 2 ng/mL definition, was 95%, 90% and 87% for low-, intermediate-, and high-risk disease, respectively. Urinary stricture was the most common genitourinary adverse event occurring in 19 patients (3.2%). At 5 years after implantation erectile function was preserved in 75% of the patients who were potent before treatment.

Conclusion

LDR brachytherapy is an effective treatment with long-term control of prostate cancer in men aged ≤60 years at time of treatment. It was associated with low rates of treatment-related toxicity and can be considered a first-line treatment for prostate cancer in this patient group.

Editorial: LDR prostate brachytherapy in younger men

Langley et al.1 report on the oncological and functional outcomes of men treated with low dose rate (LDR) prostate brachytherapy in men 60 years old or younger. 597 patients with a median (range) age of 57 (44-60) years had a median follow-up of 8.9 (1.5-17.2) years. The 10- year post-implant relapse free survival using the Phoenix definition for biochemical failure (nadir plus 2 ng/ml) was 95%, 90% and 87% for low, intermediate and high-risk disease, respectively. Potency was preserved in 75% of men potent before treatment. The authors concluded that LDR brachytherapy is an efficacious treatment with excellent long-term control of prostate cancer in men ≤60 years at time of treatment. While the results from this investigation are encouraging, enthusiasm should be tempered given the short follow up, long natural history of prostate cancer and the long-life expectancy for these younger patients.

Although the overall median follow-up was 8.9 years, the calculation of PSA-free failure was derived from a median follow-up of 5.9 years. As this investigation did not identify men who may also be at risk of failure because of a rising PSA and who have not yet reached the Phoenix threshold, I anticipate longer-follow up will further reduce their favorable results. Of the 597 men, 6 (1%) died from prostate cancer. The low incidence of prostate cancer mortality, while impressive, also reflects the short follow-up. Our group has previously reported that PCSM substantially increases between the 10th and 15th year post treatment. The experience of these physicians in prostate brachytherapy is demonstrated in their favorable dosimetry outcomes-the median D90 was 106.4% of the prescription (145 Gy). These results (median D90 154.3 Gy), which were determined and computed on the day of the implant would be 10-15% higher had the CT scans been done on day 30 as most centers do. We and others have reported that patients receiving higher dose implants have improved biochemical and cancer-specific outcomes. While these data help explain their favorable oncological outcomes, they should also serve as a guide to other brachytherapy programs where implant quality should be a primary objective. Erectile function was preserved in 75% of men. These data are consistent with other reports of younger men who were treated for prostate cancer with surgery or radiation. Because this was not a randomized study, it is not possible to make direct comparisons between surgery and brachytherapy. The selection of an IIEF score of > 11 as potent might be challenged as the 12-16 group is considered to have mild to moderate ED. Nonetheless, these data are still encouraging for younger men who are considering treatment for localized prostate cancer where sexual function preservation is important.

Nelson Stone

Mount Sinai Medical Center – Urology 350 E 72nd Street, New York, New York 10021 United States

Reference

  1. Langley SM, Soares R, Uribe J, et al. Long-term oncological outcomes and toxicity in 597 men ≤60 years of age at time of low dose rate brachytherapy for localised prostate cancer. BJU Int 2017

 

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