Fitting NTCP models to bladder doses and acute urinary symptoms during post-prostatectomy radiotherapy

Mavroidis, Panayiotis; Pearlstein, Kevin A.; Dooley, John; Sun, Jasmine; Saripalli, S.; Das, Shiva K.; Wang, Andrew Z.; Chen, Ronald C.

doi:10.1186/s13014-018-0961-x

Cited by 23 publications

(25 citation statements)

References 48 publications

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“…Physical dose distributions were converted to equivalent doses of 2 Gy per fraction (EDQ 2Gy ) using an α/β value of 3 Gy [ 18 – 20 ]. For each organ, the corresponding generalized equivalent uniform doses were calculated (gEUD 2Gy ) [ 21 , 22 ].…”

Section: Methodsmentioning

confidence: 99%

“…For the two NTCP models, the parameter values and their 95% confidence intervals were determined using the maximum likelihood method [ 18 , 27 , 28 ]. The fitting calculations were performed through the use of a minimization package (MINOS) [ 29 ].…”

Section: Methodsmentioning

confidence: 99%

“…The confidence intervals of the model parameters were determined using the profile likelihood method. The ability of the NTCP models to distinguish patients with and without the examined symptoms was evaluated using the area under the curve (AUC) measure, which is used as a summary of the ROC curve [ 18 , 30 ]. The goodness-of-fit of the different NTCP models was assessed through the Hosmer–Lemeshow test [ 31 ].…”

Section: Methodsmentioning

confidence: 99%

“…The goodness-of-fit of the different NTCP models was assessed through the Hosmer–Lemeshow test [ 31 ]. Additionally, the Odds Ratio (OR) method was applied to identify NTCP thresholds beyond which the risk of toxicity increases significantly [ 18 , 32 ]. Those thresholds were identified in three steps.…”

Section: Methodsmentioning

confidence: 99%

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NTCP modeling and dose–volume correlations for acute xerostomia and dry eye after whole brain radiation

et al. 2021

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Background Whole brain radiation (WBRT) may lead to acute xerostomia and dry eye from incidental parotid and lacrimal exposure, respectively. We performed a prospective observational study to assess the incidence/severity of this toxicity. We herein perform a secondary analysis relating parotid and lacrimal dosimetric parameters to normal tissue complication probability (NTCP) rates and associated models. Methods Patients received WBRT to 25–40 Gy in 10–20 fractions using 3D-conformal radiation therapy without prospective delineation of the parotids or lacrimals. Patients completed questionnaires at baseline and 1 month post-WBRT. Xerostomia was assessed using the University of Michigan xerostomia score (scored 0–100, toxicity defined as ≥ 20 pt increase) and xerostomia bother score (scored from 0 to 3, toxicity defined as ≥ 2 pt increase). Dry eye was assessed using the Subjective Evaluation of Symptom of Dryness (SESoD, scored from 0 to 4, toxicity defined as ≥ 2 pt increase). The clinical data were fitted by the Lyman–Kutcher–Burman (LKB) and Relative Seriality (RS) NTCP models. Results Of 55 evaluable patients, 19 (35%) had ≥ 20 point increase in xerostomia score, 11 (20%) had ≥ 2 point increase in xerostomia bother score, and 13 (24%) had ≥ 2 point increase in SESoD score. For xerostomia, parotid V10Gy–V20Gy correlated best with toxicity, with AUC 0.68 for xerostomia score and 0.69–0.71 for bother score. The values for the D50, m and n parameters of the LKB model were 22.3 Gy, 0.84 and 1.0 for xerostomia score and 28.4 Gy, 0.55 and 1.0 for bother score, respectively. The corresponding values for the D50, γ and s parameters of the RS model were 23.5 Gy, 0.28 and 0.0001 for xerostomia score and 32.0 Gy, 0.45 and 0.0001 for bother score, respectively. For dry eye, lacrimal V10Gy–V15Gy were found to correlate best with toxicity, with AUC values from 0.67 to 0.68. The parameter values of the LKB model were 53.5 Gy, 0.74 and 1.0, whereas of the RS model were 54.0 Gy, 0.37 and 0.0001, respectively. Conclusions Xerostomia was most associated with parotid V10Gy–V20Gy, and dry eye with lacrimal V10Gy–V15Gy. NTCP models were successfully created for both toxicities and may help clinicians refine dosimetric goals and assess levels of risk in patients receiving palliative WBRT.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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NTCP modeling and dose–volume correlations for acute xerostomia and dry eye after whole brain radiation

et al. 2021

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“…Based on the literature [23][24][25] it was chosen to study specific endpoints for the OARs listed in Table 2.…”

Section: Dosimetric and Radiobiological Comparisonmentioning

confidence: 99%

Dosimetric and radiobiological evaluation of four radiation techniques in preoperative rectal cancer radiotherapy

et al. 2020

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Purpose: To compare tumour dose distribution, conformality, homogeneity, normal tissue avoidance, tumour control probability (TCP) and normal tissue complication probability (NTCP) using 3D conformal radiation therapy (3DCRT), 3- and 4-field intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) in patients with locally advanced rectal cancer. Materials and methods: Twenty-four patients staged T1–3N+M0 with locally advanced rectal cancer underwent neoadjuvant chemoradiation therapy. Four different radiotherapy plans were prepared for each patient: 3DCRT, 3- and 4-field IMRT and VMAT are evaluated for target distribution using CI and homogeneity index (HI), normal tissue avoidance using Dmax, V45, V40, V50 and TCP and NTCP using the Lyman–Kutcher–Burman model. Results: VMAT has better HI (HI = 1·32) and 3DCRT exhibited better conformality (CI = 1·05) than the other radiotherapy techniques. With regard to normal tissue avoidance, all radiotherapy plans met the constraints. Dmax in the 3DCRT plans was statistically significant (p = 0·04) for bladder and no significant differences in V40 and V50. In the bowel bag, no significant differences in Dmax for any radiotherapy plan and V40 was lower in 3DCRT than VMAT (p = 0·024). In the case of femoral heads, 3DCRT has a statistically significant lower dose on Dmax than 4-field IMRT (p = 0·00 « 0·05). VMAT has the biggest TCP (80·76%) than the other three radiotherapy plans. With regard to normal tissue complications, probabilities were shown to be very low, of the order of 10-14 and 10-41 for bowel bag and femoral heads respectively. Conclusions: It can be concluded that 3DCRT plan improves conformity and decreases radiation sparing in the organ at risks, but the VMAT plan exhibits better homogeneity and greater TCP.

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Evaluation of the clinical impact of the differences between planned and delivered dose in prostate cancer radiotherapy based on CT‐on‐rails IGRT and patient‐reported outcome scores

Hammers

Lindsay

Narayanasamy

et al. 2022

J Applied Clin Med Phys

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Purpose To estimate the clinical impact of differences between delivered and planned dose using dose metrics and normal tissue complication probability (NTCP) modeling. Methods Forty‐six consecutive patients with prostate adenocarcinoma between 2010 and 2015 treated with intensity‐modulated radiation therapy (IMRT) and who had undergone computed tomography on rails imaging were included. Delivered doses to bladder and rectum were estimated using a contour‐based deformable image registration method. The bladder and rectum NTCP were calculated using dose–response parameters applied to planned and delivered dose distributions. Seven urinary and gastrointestinal symptoms were prospectively collected using the validated prostate cancer symptom indices patient reported outcome (PRO) at pre‐treatment, weekly treatment, and post‐treatment follow‐up visits. Correlations between planned and delivered doses against PRO were evaluated in this study. Results Planned mean doses to bladder and rectum were 44.9 ± 13.6 Gy and 42.8 ± 7.3 Gy, while delivered doses were 46.1 ± 13.4 Gy and 41.3 ± 8.7 Gy, respectively. D 10cc for rectum was 64.1 ± 7.6 Gy for planned and 60.1 ± 9.3 Gy for delivered doses. NTCP values of treatment plan were 22.3% ± 8.4% and 12.6% ± 5.9%, while those for delivered doses were 23.2% ± 8.4% and 9.9% ± 8.3% for bladder and rectum, respectively. Seven of 25 patients with follow‐up data showed urinary complications (28%) and three had rectal complications (12%). Correlations of NTCP values of planned and delivered doses with PRO follow‐up data were random for bladder and moderate for rectum (0.68 and 0.67, respectively). Conclusion Sensitivity of bladder to clinical variations of dose accumulation indicates that an automated solution based on a DIR that considers inter‐fractional organ deformation could recommend intervention. This is intended to achieve additional rectum sparing in cases that indicate higher than expected dose accumulation early during patient treatment in order to prevent acute severity of bowel symptoms.

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Fitting NTCP models to bladder doses and acute urinary symptoms during post-prostatectomy radiotherapy

Cited by 23 publications

References 48 publications

NTCP modeling and dose–volume correlations for acute xerostomia and dry eye after whole brain radiation

NTCP modeling and dose–volume correlations for acute xerostomia and dry eye after whole brain radiation

Dosimetric and radiobiological evaluation of four radiation techniques in preoperative rectal cancer radiotherapy

Evaluation of the clinical impact of the differences between planned and delivered dose in prostate cancer radiotherapy based on CT‐on‐rails IGRT and patient‐reported outcome scores

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