Multivariable model development and internal validation for prostate cancer specific survival and overall survival after whole-gland salvage Iodine-125 prostate brachytherapy

Peters, Max; Zyp, Jochem R.N. van der Voort van; Moerland, Marinus A.; Hoekstra, C.J.M.; Pol, S. van de; Westendorp, R.; Maenhout, M.; Kattevilder, Rob; Verkooijen, Helena M.; Rossum, Peter S.N. van; Ahmed, Hashim U.; Shah, Taimur T.; Emberton, Mark; Vulpen, Marco van

doi:10.1016/j.radonc.2016.02.002

Cited by 10 publications

(4 citation statements)

References 28 publications

(47 reference statements)

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“…In the patient with the salvage relapse, the interval between primary and salvage treatment was 2.5 years, but the PSA-DT was relatively short at 12.1 months. A short disease-free survival time and short PSA-DT may be predictors of subsequent treatment failure in whole-gland salvage iodine-125 BT, 31 which might explain the early progression in this patient.…”

Section: Discussionmentioning

confidence: 89%

Focal MRI-Guided Salvage High-Dose-Rate Brachytherapy in Patients With Radiorecurrent Prostate Cancer

Maenhout

Vulpen

Moerland

et al. 2017

Technol Cancer Res Treat

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Introduction:Whole-gland salvage treatment of radiorecurrent prostate cancer has a high rate of severe toxicity. The standard of care in case of a biochemical recurrence is androgen deprivation treatment, which is associated with morbidity and negative effects on quality of life. A salvage treatment with acceptable toxicity might postpone the start of androgen deprivation treatment, might have a positive influence on the patients’ quality of life, and might even be curative. Here, toxicity and biochemical outcome are described after magnetic resonance imaging–guided focal salvage high-dose-rate brachytherapy in patients with radiorecurrent prostate cancer.Materials and Methods:Seventeen patients with pathologically proven locally recurrent prostate cancer were treated with focal high-dose-rate brachytherapy in a single 19-Gy fraction using magnetic resonance imaging for treatment guidance. Primary radiotherapy consisted of external beam radiotherapy or low-dose-rate brachytherapy. Tumors were delineated with Ga-68–prostate-specific membrane antigen or F18-choline positron emission tomography in combination with multiparametric magnetic resonance imaging. All patients had a prostate-specific antigen level of less than 10 ng/mL at the time of recurrence and a prostate-specific antigen doubling time of ≥12 months. Toxicity was measured by using the Common Terminology Criteria for Adverse Events version 4.Results:Eight of 17 patients had follow-up interval of at least 1 year. At a median follow-up interval of 10 months (range 3-40 months), 1 patient experienced a biochemical recurrence according to the Phoenix criteria, and prostate-specific membrane antigen testing revealed that this was due to a distant nodal metastasis. One patient had a grade 3 urethral stricture at 2 years after treatment.Conclusion:Focal salvage high-dose-rate brachytherapy in patients with radiorecurrent prostate cancer showed grade 3 toxicity in 1 of 17 patients and a distant nodal metastasis in another patient. Whether this treatment option leads to cure in a subset of patients or whether it can successfully postpone androgen deprivation treatment needs further investigation.

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Section: Discussionmentioning

confidence: 89%

Focal MRI-Guided Salvage High-Dose-Rate Brachytherapy in Patients With Radiorecurrent Prostate Cancer

Maenhout

Vulpen

Moerland

et al. 2017

Technol Cancer Res Treat

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“…Based on the studies evaluated in this review, salvage LDR-BT appeared to have the potential for higher grade 3+ toxicity compared to HDR-BT ( 19 , 24 ). In a study which used PROMs, LDR-BT had a higher peak change in IPSS in the early post-implant period and a higher peak urinary symptom flare at 12 months compared with HDR-BT, although the majority of these scores returned to baseline 2-3 years post-treatment ( 40 ).…”

Section: Discussionmentioning

confidence: 99%

“…Four were multi-centre and 24 were single centre. Twelve BT studies used LDR only (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27), 11 used HDR only (28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39), 4 used LDR or HDR (40)(41)(42)(43) and 1 used PDR only (44). Twenty four studies used whole gland salvage treatments and 4 studies used focal salvage treatments (16,34,36,38).…”

Section: Treatment Detailsmentioning

confidence: 99%

Salvage Reirradiation Options for Locally Recurrent Prostate Cancer: A Systematic Review

et al. 2021

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BackgroundReirradiation using brachytherapy (BT) and external beam radiation therapy (EBRT) are salvage strategies with locally radiorecurrent prostate cancer. This systematic review describes the oncologic and toxicity outcomes for salvage BT and EBRT [including Stereotactic Body Radiation Therapy (SBRT)].MethodsAn International Prospective Register of Systematic Reviews (PROSPERO) registered (#211875) study was conducted using Preferred Reporting Items for Systematic reviews and Meta-analyses (PRISMA) guidelines. EMBASE and MEDLINE databases were searched from inception to December 2020. For BT, both low dose rate (LDR) and high dose rate (HDR) BT techniques were included. Two authors independently assessed study quality using the 18-item Modified Delphi technique.ResultsA total of 39 eligible studies comprising 1967 patients were included (28 BT and 11 SBRT). In 35 studies (90%), the design was single centre and/or retrospective and no randomised prospective studies were found. Twelve BT studies used LDR only, 11 HDR only, 4 LDR or HDR and 1 pulsed-dose rate only. All EBRT studies used SBRT exclusively, four with Cyberknife alone and 7 using both Cyberknife and conventional linear accelerator treatments. Median (range) modified Delphi quality score was 15 (6-18). Median (range) follow-up was 47.5 months (13-108) (BT) and 25.4 months (21-44) (SBRT). For the LDR-BT studies, the median (range) 2-year and 5-year bRFS rates were 71% (48-89.5) and 52.5% (20-79). For the HDR-BT studies, the median (range) 2-year and 5-year bRFS rates were 74% (63-89) and 51% (45-65). For the SBRT studies, the median (range) 2-year bRFS for the SBRT group was 54.9% (40-80). Mean (range) acute and late grade≥3 GU toxicity rates for LDR-BT/HDR-BT/SBRT were 7.4%(0-14)/2%(0-14)/2.7%(0-8.7) and 13.6%(0-30)/7.9%(0-21.3%)/2.7%(0-8%). Mean (range) acute and late grade≥3 GI toxicity rates for LDR-BT/HDR-BT/SBRT were 6.5%(0-19)/0%/0.5%(0-4%) and 6.4%(0-20)/0.1%(0-0.9)/0.2%(0-1.5). One third of studies included Patient Reported Outcome Measures (PROMs).ConclusionsSalvage reirradiation of radiorecurrent prostate cancer using HDR-BT or SBRT provides similar biochemical control and acceptable late toxicity. Salvage LDR-BT is associated with higher late GU/GI toxicity. Challenges exist in comparing BT and SBRT from inconsistencies in reporting with missing data, and prospective randomised trials are needed.

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“…Rather than discard the observations or variables with missing information, it is suggested to impute any missing data, with sophisticated methods such as multiple imputation being advocated [4]. However, few published models implement imputation, particularly when considering survival outcomes [7][8][9]. Furthermore, the implications of multiple imputation on model development and validation are rarely discussed in publications, with the clinical impact of the model usually receiving more attention.…”

Section: Introductionmentioning

confidence: 99%

The development and validation of prognostic models for overall survival in the presence of missing data in the training dataset: a strategy with a detailed example

Royle

Cairns

2021

Diagn Progn Res

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Background The United Kingdom Myeloma Research Alliance (UK-MRA) Myeloma Risk Profile is a prognostic model for overall survival. It was trained and tested on clinical trial data, aiming to improve the stratification of transplant ineligible (TNE) patients with newly diagnosed multiple myeloma. Missing data is a common problem which affects the development and validation of prognostic models, where decisions on how to address missingness have implications on the choice of methodology. Methods Model building The training and test datasets were the TNE pathways from two large randomised multicentre, phase III clinical trials. Potential prognostic factors were identified by expert opinion. Missing data in the training dataset was imputed using multiple imputation by chained equations. Univariate analysis fitted Cox proportional hazards models in each imputed dataset with the estimates combined by Rubin’s rules. Multivariable analysis applied penalised Cox regression models, with a fixed penalty term across the imputed datasets. The estimates from each imputed dataset and bootstrap standard errors were combined by Rubin’s rules to define the prognostic model. Model assessment Calibration was assessed by visualising the observed and predicted probabilities across the imputed datasets. Discrimination was assessed by combining the prognostic separation D-statistic from each imputed dataset by Rubin’s rules. Model validation The D-statistic was applied in a bootstrap internal validation process in the training dataset and an external validation process in the test dataset, where acceptable performance was pre-specified. Development of risk groups Risk groups were defined using the tertiles of the combined prognostic index, obtained by combining the prognostic index from each imputed dataset by Rubin’s rules. Results The training dataset included 1852 patients, 1268 (68.47%) with complete case data. Ten imputed datasets were generated. Five hundred twenty patients were included in the test dataset. The D-statistic for the prognostic model was 0.840 (95% CI 0.716–0.964) in the training dataset and 0.654 (95% CI 0.497–0.811) in the test dataset and the corrected D-Statistic was 0.801. Conclusion The decision to impute missing covariate data in the training dataset influenced the methods implemented to train and test the model. To extend current literature and aid future researchers, we have presented a detailed example of one approach. Whilst our example is not without limitations, a benefit is that all of the patient information available in the training dataset was utilised to develop the model. Trial registration Both trials were registered; Myeloma IX-ISRCTN68454111, registered 21 September 2000. Myeloma XI-ISRCTN49407852, registered 24 June 2009.

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Multivariable model development and internal validation for prostate cancer specific survival and overall survival after whole-gland salvage Iodine-125 prostate brachytherapy

Cited by 10 publications

References 28 publications

Focal MRI-Guided Salvage High-Dose-Rate Brachytherapy in Patients With Radiorecurrent Prostate Cancer

Focal MRI-Guided Salvage High-Dose-Rate Brachytherapy in Patients With Radiorecurrent Prostate Cancer

Salvage Reirradiation Options for Locally Recurrent Prostate Cancer: A Systematic Review

The development and validation of prognostic models for overall survival in the presence of missing data in the training dataset: a strategy with a detailed example

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