Bladder spatial-dose descriptors correlate with acute urinary toxicity after radiation therapy for prostate cancer

Ilaria Improta, F Palorini, C Cozzarini, T Rancati, B Avuzzi, P. Franco, Claudio Degli Esposti, E. Del Mastro, G. Girelli, C Iotti, Virna Vavassori, R Valdagni, C Fiorino

Research output: Contribution to journalArticle

Abstract

PURPOSE: To assess bladder spatial-dose parameters predicting acute urinary toxicity after radiotherapy for prostate cancer (PCa) through a pixel-wise method for analysis of bladder dose-surface maps (DSMs).

MATERIALS & METHODS: The final cohort of a multi-institutional study, consisting of 539 patients with PCa treated with conventionally (CONV:1.8-2Gy/fr) or moderately hypo-fractionated radiotherapy (HYPO:2.2-2.7Gy/fr) was considered. Urinary toxicity was evaluated through the International Prostate Symptoms Score (IPSS) administered before and after radiotherapy. IPSS increases ⩾10 and 15 points at the end of radiotherapy (ΔIPSS⩾10 and ΔIPSS⩾15) were chosen as endpoints. Average DSMs (corrected into 2Gy-equivalent doses) of patients with/without toxicity were compared through a pixel-wise method. This allowed the extraction of selected spatial descriptors discriminating between patients with/without toxicity. Previously logistic models based on dose-surface histograms (DSH) were considered and replaced with DSM descriptors. Discrimination power, calibration and log-likelihood were considered to evaluate the impact of the inclusion of spatial descriptors.

RESULTS: Data of 375/539 patients were available. ΔIPSS⩾10 was recorded in 76/375 (20%) patients, while 30/375 (8%) experienced ΔIPSS⩾15. The posterior dose at 12mm from the bladder base (roughly corresponding to the trigone region) resulted significantly associated to toxicity in the whole/HYPO populations. The cranial extension of the 75Gy isodose along the bladder central axis was the best DSM-based predictor in CONV patients. Multi-variable models including DSM descriptors showed better discrimination (AUC=0.66-0.77) when compared to DSH-based models (AUC=0.58-0.71) and higher log-likelihoods.

CONCLUSION: DSMs are correlated with the risk of acute GU toxicity. The incorporation of spatial descriptors improves discrimination and log-likelihood of multi-variable models including dosimetric and clinical parameters.

Original languageEnglish
Pages (from-to)1681-1689
Number of pages9
JournalPhysica Medica
Volume32
Issue number12
DOIs
Publication statusPublished - Dec 2016

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bladder
toxicity
radiation therapy
Prostatic Neoplasms
Urinary Bladder
Radiotherapy
cancer
dosage
Area Under Curve
Prostate
discrimination
histograms
Calibration
pixels
Logistic Models
logistics
Population
inclusions

Keywords

  • Journal Article

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Bladder spatial-dose descriptors correlate with acute urinary toxicity after radiation therapy for prostate cancer. / Improta, Ilaria; Palorini, F; Cozzarini, C; Rancati, T; Avuzzi, B; Franco, P.; Degli Esposti, Claudio; Del Mastro, E.; Girelli, G.; Iotti, C; Vavassori, Virna; Valdagni, R; Fiorino, C.

In: Physica Medica, Vol. 32, No. 12, 12.2016, p. 1681-1689.

Research output: Contribution to journalArticle

Improta, Ilaria ; Palorini, F ; Cozzarini, C ; Rancati, T ; Avuzzi, B ; Franco, P. ; Degli Esposti, Claudio ; Del Mastro, E. ; Girelli, G. ; Iotti, C ; Vavassori, Virna ; Valdagni, R ; Fiorino, C. / Bladder spatial-dose descriptors correlate with acute urinary toxicity after radiation therapy for prostate cancer. In: Physica Medica. 2016 ; Vol. 32, No. 12. pp. 1681-1689.
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abstract = "PURPOSE: To assess bladder spatial-dose parameters predicting acute urinary toxicity after radiotherapy for prostate cancer (PCa) through a pixel-wise method for analysis of bladder dose-surface maps (DSMs).MATERIALS & METHODS: The final cohort of a multi-institutional study, consisting of 539 patients with PCa treated with conventionally (CONV:1.8-2Gy/fr) or moderately hypo-fractionated radiotherapy (HYPO:2.2-2.7Gy/fr) was considered. Urinary toxicity was evaluated through the International Prostate Symptoms Score (IPSS) administered before and after radiotherapy. IPSS increases ⩾10 and 15 points at the end of radiotherapy (ΔIPSS⩾10 and ΔIPSS⩾15) were chosen as endpoints. Average DSMs (corrected into 2Gy-equivalent doses) of patients with/without toxicity were compared through a pixel-wise method. This allowed the extraction of selected spatial descriptors discriminating between patients with/without toxicity. Previously logistic models based on dose-surface histograms (DSH) were considered and replaced with DSM descriptors. Discrimination power, calibration and log-likelihood were considered to evaluate the impact of the inclusion of spatial descriptors.RESULTS: Data of 375/539 patients were available. ΔIPSS⩾10 was recorded in 76/375 (20{\%}) patients, while 30/375 (8{\%}) experienced ΔIPSS⩾15. The posterior dose at 12mm from the bladder base (roughly corresponding to the trigone region) resulted significantly associated to toxicity in the whole/HYPO populations. The cranial extension of the 75Gy isodose along the bladder central axis was the best DSM-based predictor in CONV patients. Multi-variable models including DSM descriptors showed better discrimination (AUC=0.66-0.77) when compared to DSH-based models (AUC=0.58-0.71) and higher log-likelihoods.CONCLUSION: DSMs are correlated with the risk of acute GU toxicity. The incorporation of spatial descriptors improves discrimination and log-likelihood of multi-variable models including dosimetric and clinical parameters.",
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T1 - Bladder spatial-dose descriptors correlate with acute urinary toxicity after radiation therapy for prostate cancer

AU - Improta, Ilaria

AU - Palorini, F

AU - Cozzarini, C

AU - Rancati, T

AU - Avuzzi, B

AU - Franco, P.

AU - Degli Esposti, Claudio

AU - Del Mastro, E.

AU - Girelli, G.

AU - Iotti, C

AU - Vavassori, Virna

AU - Valdagni, R

AU - Fiorino, C

N1 - Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

PY - 2016/12

Y1 - 2016/12

N2 - PURPOSE: To assess bladder spatial-dose parameters predicting acute urinary toxicity after radiotherapy for prostate cancer (PCa) through a pixel-wise method for analysis of bladder dose-surface maps (DSMs).MATERIALS & METHODS: The final cohort of a multi-institutional study, consisting of 539 patients with PCa treated with conventionally (CONV:1.8-2Gy/fr) or moderately hypo-fractionated radiotherapy (HYPO:2.2-2.7Gy/fr) was considered. Urinary toxicity was evaluated through the International Prostate Symptoms Score (IPSS) administered before and after radiotherapy. IPSS increases ⩾10 and 15 points at the end of radiotherapy (ΔIPSS⩾10 and ΔIPSS⩾15) were chosen as endpoints. Average DSMs (corrected into 2Gy-equivalent doses) of patients with/without toxicity were compared through a pixel-wise method. This allowed the extraction of selected spatial descriptors discriminating between patients with/without toxicity. Previously logistic models based on dose-surface histograms (DSH) were considered and replaced with DSM descriptors. Discrimination power, calibration and log-likelihood were considered to evaluate the impact of the inclusion of spatial descriptors.RESULTS: Data of 375/539 patients were available. ΔIPSS⩾10 was recorded in 76/375 (20%) patients, while 30/375 (8%) experienced ΔIPSS⩾15. The posterior dose at 12mm from the bladder base (roughly corresponding to the trigone region) resulted significantly associated to toxicity in the whole/HYPO populations. The cranial extension of the 75Gy isodose along the bladder central axis was the best DSM-based predictor in CONV patients. Multi-variable models including DSM descriptors showed better discrimination (AUC=0.66-0.77) when compared to DSH-based models (AUC=0.58-0.71) and higher log-likelihoods.CONCLUSION: DSMs are correlated with the risk of acute GU toxicity. The incorporation of spatial descriptors improves discrimination and log-likelihood of multi-variable models including dosimetric and clinical parameters.

AB - PURPOSE: To assess bladder spatial-dose parameters predicting acute urinary toxicity after radiotherapy for prostate cancer (PCa) through a pixel-wise method for analysis of bladder dose-surface maps (DSMs).MATERIALS & METHODS: The final cohort of a multi-institutional study, consisting of 539 patients with PCa treated with conventionally (CONV:1.8-2Gy/fr) or moderately hypo-fractionated radiotherapy (HYPO:2.2-2.7Gy/fr) was considered. Urinary toxicity was evaluated through the International Prostate Symptoms Score (IPSS) administered before and after radiotherapy. IPSS increases ⩾10 and 15 points at the end of radiotherapy (ΔIPSS⩾10 and ΔIPSS⩾15) were chosen as endpoints. Average DSMs (corrected into 2Gy-equivalent doses) of patients with/without toxicity were compared through a pixel-wise method. This allowed the extraction of selected spatial descriptors discriminating between patients with/without toxicity. Previously logistic models based on dose-surface histograms (DSH) were considered and replaced with DSM descriptors. Discrimination power, calibration and log-likelihood were considered to evaluate the impact of the inclusion of spatial descriptors.RESULTS: Data of 375/539 patients were available. ΔIPSS⩾10 was recorded in 76/375 (20%) patients, while 30/375 (8%) experienced ΔIPSS⩾15. The posterior dose at 12mm from the bladder base (roughly corresponding to the trigone region) resulted significantly associated to toxicity in the whole/HYPO populations. The cranial extension of the 75Gy isodose along the bladder central axis was the best DSM-based predictor in CONV patients. Multi-variable models including DSM descriptors showed better discrimination (AUC=0.66-0.77) when compared to DSH-based models (AUC=0.58-0.71) and higher log-likelihoods.CONCLUSION: DSMs are correlated with the risk of acute GU toxicity. The incorporation of spatial descriptors improves discrimination and log-likelihood of multi-variable models including dosimetric and clinical parameters.

KW - Journal Article

U2 - 10.1016/j.ejmp.2016.08.013

DO - 10.1016/j.ejmp.2016.08.013

M3 - Article

C2 - 27570122

VL - 32

SP - 1681

EP - 1689

JO - Physica Medica

JF - Physica Medica

SN - 1120-1797

IS - 12

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