Development and internal validation of a multivariable prediction model for biochemical failure after whole-gland salvage iodine-125 prostate brachytherapy for recurrent prostate cancer

M Peters; J R N van der Voort van Zyp; M A Moerland; C J Hoekstra; S van de Pol; H Westendorp; M Maenhout; R Kattevilder; H M Verkooijen; P S N van Rossum; H U Ahmed; T T Shah; M Emberton; M van Vulpen

doi:10.1016/j.brachy.2016.01.004

Development and internal validation of a multivariable prediction model for biochemical failure after whole-gland salvage iodine-125 prostate brachytherapy for recurrent prostate cancer

M Peters, J R N van der Voort van Zyp, M A Moerland, C J Hoekstra, S van de Pol, H Westendorp, M Maenhout, R Kattevilder, H M Verkooijen, P S N van Rossum, H U Ahmed, T T Shah, M Emberton, M van Vulpen

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

BACKGROUND: Localized recurrent prostate cancer after primary radiotherapy can be curatively treated using salvage iodine-125 ((125)I) brachytherapy. Selection is hampered by a lack of predictive factors for cancer control. This study aims to develop and internally validate a prognostic model for biochemical failure (BF) after salvage (125)I brachytherapy.

METHODS AND MATERIALS: Whole-gland salvage (125)I brachytherapy patients were treated between 1993 and 2010 in two radiotherapy centers in the Netherlands. Multivariable Cox regression was performed to assess the predictive value of clinical parameters related to BF (Phoenix-definition [prostate-specific antigen [PSA]-nadir + 2.0 ng/mL]). Missing data were handled by multiple imputation. The model's discriminatory ability was assessed with Harrell's C-statistic. Internal validation was performed using bootstrap resampling (2000 data sets). Goodness-of-fit was evaluated with calibration plots. All analyses were performed using the recently published TRIPOD (Transparent reporting of a multivariable prediction model for individual prognosis or diagnosis) statement.

RESULTS: After median followup of 74 months (range 5-138), 43 of a total 62 patients developed BF. In multivariable analysis, disease-free survival interval (DFSI) after primary therapy and pre-salvage prostate-specific antigen doubling time (PSADT) were predictors of BF: corrected hazard ratio (HR) 0.99 (95% confidence interval 0.97-0.999; p = 0.04) and 0.94 (95% confidence interval 0.89-0.99; p = 0.03), both for a 1-month increase (optimism-adjusted C-statistic 0.70). Calibration was accurate up to 36 months. Of patients with PSADT >30 months and DFSI >60 months, 36-month biochemical disease-free survival was >75%. Every 12-month increase in DFSI will allow 3-month decrease in PSADT while maintaining the same biochemical recurrence-free rates.

CONCLUSIONS: We have presented results from a cohort of patients undergoing salvage (125)I-brachytherapy. Our data show that better selection of patients is possible with the DFSI and PSADT.

Original language	English
Pages (from-to)	296-305
Number of pages	10
Journal	Brachytherapy
Volume	15
Issue number	3
DOIs	https://doi.org/10.1016/j.brachy.2016.01.004
Publication status	Published - 8 Mar 2016

Keywords

Whole-gland salvage
Prostate cancer
125I brachytherapy
Prediction model
Biochemical failure

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10.1016/j.brachy.2016.01.004

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Peters, M., van der Voort van Zyp, J. R. N., Moerland, M. A., Hoekstra, C. J., van de Pol, S., Westendorp, H., Maenhout, M., Kattevilder, R., Verkooijen, H. M., van Rossum, P. S. N., Ahmed, H. U., Shah, T. T., Emberton, M., & van Vulpen, M. (2016). Development and internal validation of a multivariable prediction model for biochemical failure after whole-gland salvage iodine-125 prostate brachytherapy for recurrent prostate cancer. Brachytherapy, 15(3), 296-305. https://doi.org/10.1016/j.brachy.2016.01.004

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title = "Development and internal validation of a multivariable prediction model for biochemical failure after whole-gland salvage iodine-125 prostate brachytherapy for recurrent prostate cancer",

abstract = "BACKGROUND: Localized recurrent prostate cancer after primary radiotherapy can be curatively treated using salvage iodine-125 ((125)I) brachytherapy. Selection is hampered by a lack of predictive factors for cancer control. This study aims to develop and internally validate a prognostic model for biochemical failure (BF) after salvage (125)I brachytherapy.METHODS AND MATERIALS: Whole-gland salvage (125)I brachytherapy patients were treated between 1993 and 2010 in two radiotherapy centers in the Netherlands. Multivariable Cox regression was performed to assess the predictive value of clinical parameters related to BF (Phoenix-definition [prostate-specific antigen [PSA]-nadir + 2.0 ng/mL]). Missing data were handled by multiple imputation. The model's discriminatory ability was assessed with Harrell's C-statistic. Internal validation was performed using bootstrap resampling (2000 data sets). Goodness-of-fit was evaluated with calibration plots. All analyses were performed using the recently published TRIPOD (Transparent reporting of a multivariable prediction model for individual prognosis or diagnosis) statement.RESULTS: After median followup of 74 months (range 5-138), 43 of a total 62 patients developed BF. In multivariable analysis, disease-free survival interval (DFSI) after primary therapy and pre-salvage prostate-specific antigen doubling time (PSADT) were predictors of BF: corrected hazard ratio (HR) 0.99 (95% confidence interval 0.97-0.999; p = 0.04) and 0.94 (95% confidence interval 0.89-0.99; p = 0.03), both for a 1-month increase (optimism-adjusted C-statistic 0.70). Calibration was accurate up to 36 months. Of patients with PSADT >30 months and DFSI >60 months, 36-month biochemical disease-free survival was >75%. Every 12-month increase in DFSI will allow 3-month decrease in PSADT while maintaining the same biochemical recurrence-free rates.CONCLUSIONS: We have presented results from a cohort of patients undergoing salvage (125)I-brachytherapy. Our data show that better selection of patients is possible with the DFSI and PSADT.",

keywords = "Whole-gland salvage, Prostate cancer, 125I brachytherapy, Prediction model, Biochemical failure",

author = "M Peters and {van der Voort van Zyp}, {J R N} and Moerland, {M A} and Hoekstra, {C J} and {van de Pol}, S and H Westendorp and M Maenhout and R Kattevilder and Verkooijen, {H M} and {van Rossum}, {P S N} and Ahmed, {H U} and Shah, {T T} and M Emberton and {van Vulpen}, M",

year = "2016",

month = mar,

day = "8",

doi = "10.1016/j.brachy.2016.01.004",

language = "English",

volume = "15",

pages = "296--305",

journal = "Brachytherapy",

issn = "1538-4721",

publisher = "Elsevier",

number = "3",

}

Peters, M, van der Voort van Zyp, JRN, Moerland, MA, Hoekstra, CJ, van de Pol, S, Westendorp, H, Maenhout, M, Kattevilder, R, Verkooijen, HM, van Rossum, PSN, Ahmed, HU, Shah, TT, Emberton, M & van Vulpen, M 2016, 'Development and internal validation of a multivariable prediction model for biochemical failure after whole-gland salvage iodine-125 prostate brachytherapy for recurrent prostate cancer', Brachytherapy, vol. 15, no. 3, pp. 296-305. https://doi.org/10.1016/j.brachy.2016.01.004

Development and internal validation of a multivariable prediction model for biochemical failure after whole-gland salvage iodine-125 prostate brachytherapy for recurrent prostate cancer. / Peters, M; van der Voort van Zyp, J R N; Moerland, M A et al.
In: Brachytherapy, Vol. 15, No. 3, 08.03.2016, p. 296-305.

Research output: Contribution to journal › Article › Academic › peer-review

TY - JOUR

T1 - Development and internal validation of a multivariable prediction model for biochemical failure after whole-gland salvage iodine-125 prostate brachytherapy for recurrent prostate cancer

AU - Peters, M

AU - van der Voort van Zyp, J R N

AU - Moerland, M A

AU - Hoekstra, C J

AU - van de Pol, S

AU - Westendorp, H

AU - Maenhout, M

AU - Kattevilder, R

AU - Verkooijen, H M

AU - van Rossum, P S N

AU - Ahmed, H U

AU - Shah, T T

AU - Emberton, M

AU - van Vulpen, M

PY - 2016/3/8

Y1 - 2016/3/8

N2 - BACKGROUND: Localized recurrent prostate cancer after primary radiotherapy can be curatively treated using salvage iodine-125 ((125)I) brachytherapy. Selection is hampered by a lack of predictive factors for cancer control. This study aims to develop and internally validate a prognostic model for biochemical failure (BF) after salvage (125)I brachytherapy.METHODS AND MATERIALS: Whole-gland salvage (125)I brachytherapy patients were treated between 1993 and 2010 in two radiotherapy centers in the Netherlands. Multivariable Cox regression was performed to assess the predictive value of clinical parameters related to BF (Phoenix-definition [prostate-specific antigen [PSA]-nadir + 2.0 ng/mL]). Missing data were handled by multiple imputation. The model's discriminatory ability was assessed with Harrell's C-statistic. Internal validation was performed using bootstrap resampling (2000 data sets). Goodness-of-fit was evaluated with calibration plots. All analyses were performed using the recently published TRIPOD (Transparent reporting of a multivariable prediction model for individual prognosis or diagnosis) statement.RESULTS: After median followup of 74 months (range 5-138), 43 of a total 62 patients developed BF. In multivariable analysis, disease-free survival interval (DFSI) after primary therapy and pre-salvage prostate-specific antigen doubling time (PSADT) were predictors of BF: corrected hazard ratio (HR) 0.99 (95% confidence interval 0.97-0.999; p = 0.04) and 0.94 (95% confidence interval 0.89-0.99; p = 0.03), both for a 1-month increase (optimism-adjusted C-statistic 0.70). Calibration was accurate up to 36 months. Of patients with PSADT >30 months and DFSI >60 months, 36-month biochemical disease-free survival was >75%. Every 12-month increase in DFSI will allow 3-month decrease in PSADT while maintaining the same biochemical recurrence-free rates.CONCLUSIONS: We have presented results from a cohort of patients undergoing salvage (125)I-brachytherapy. Our data show that better selection of patients is possible with the DFSI and PSADT.

AB - BACKGROUND: Localized recurrent prostate cancer after primary radiotherapy can be curatively treated using salvage iodine-125 ((125)I) brachytherapy. Selection is hampered by a lack of predictive factors for cancer control. This study aims to develop and internally validate a prognostic model for biochemical failure (BF) after salvage (125)I brachytherapy.METHODS AND MATERIALS: Whole-gland salvage (125)I brachytherapy patients were treated between 1993 and 2010 in two radiotherapy centers in the Netherlands. Multivariable Cox regression was performed to assess the predictive value of clinical parameters related to BF (Phoenix-definition [prostate-specific antigen [PSA]-nadir + 2.0 ng/mL]). Missing data were handled by multiple imputation. The model's discriminatory ability was assessed with Harrell's C-statistic. Internal validation was performed using bootstrap resampling (2000 data sets). Goodness-of-fit was evaluated with calibration plots. All analyses were performed using the recently published TRIPOD (Transparent reporting of a multivariable prediction model for individual prognosis or diagnosis) statement.RESULTS: After median followup of 74 months (range 5-138), 43 of a total 62 patients developed BF. In multivariable analysis, disease-free survival interval (DFSI) after primary therapy and pre-salvage prostate-specific antigen doubling time (PSADT) were predictors of BF: corrected hazard ratio (HR) 0.99 (95% confidence interval 0.97-0.999; p = 0.04) and 0.94 (95% confidence interval 0.89-0.99; p = 0.03), both for a 1-month increase (optimism-adjusted C-statistic 0.70). Calibration was accurate up to 36 months. Of patients with PSADT >30 months and DFSI >60 months, 36-month biochemical disease-free survival was >75%. Every 12-month increase in DFSI will allow 3-month decrease in PSADT while maintaining the same biochemical recurrence-free rates.CONCLUSIONS: We have presented results from a cohort of patients undergoing salvage (125)I-brachytherapy. Our data show that better selection of patients is possible with the DFSI and PSADT.

KW - Whole-gland salvage

KW - Prostate cancer

KW - 125I brachytherapy

KW - Prediction model

KW - Biochemical failure

U2 - 10.1016/j.brachy.2016.01.004

DO - 10.1016/j.brachy.2016.01.004

M3 - Article

C2 - 26948662

SN - 1538-4721

VL - 15

SP - 296

EP - 305

JO - Brachytherapy

JF - Brachytherapy

IS - 3

ER -

Development and internal validation of a multivariable prediction model for biochemical failure after whole-gland salvage iodine-125 prostate brachytherapy for recurrent prostate cancer

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Keywords

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