TY - JOUR
T1 - Inclusion of clinical risk factors into NTCP modelling of late rectal toxicity after high dose radiotherapy for prostate cancer
AU - Rancati, Tiziana
AU - Fiorino, Claudio
AU - Fellin, Gianni
AU - Vavassori, Vittorio
AU - Cagna, Emanuela
AU - Casanova Borca, Valeria
AU - Girelli, Giuseppe
AU - Menegotti, Loris
AU - Monti, Angelo Filippo
AU - Tortoreto, Francesca
AU - Delle Canne, Stefania
AU - Valdagni, Riccardo
PY - 2011/7
Y1 - 2011/7
N2 - Background and purpose: To fit an NTCP model including clinical risk factors to late rectal toxicities after radiotherapy for prostate cancer. Methods and materials: Data of 669 patients were considered. The probability of late toxicity within 36 months (bleeding and incontinence) was fitted with the original and a modified Logit-EUD model, including clinical factors by fitting a subset specific TD 50s: the ratio of TD 50s with and without including the clinical variable was the dose-modifying factor (D mod). Results: Abdominal surgery (surg) was a risk factor for G2-G3 bleeding, reflecting in a TD 50 = 82.7 Gy and 88.4 Gy for patients with and without surg (D mod = 0.94; 0.90 for G3 bleeding); acute toxicity was also an important risk factor for G2-G3 bleeding (D mod = 0.93). Concerning incontinence, surg and previous diseases of the colon were the clinical co-factors. D mod(surg) and D mod(colon) were 0.50 and 0.42, respectively for chronic incontinence and 0.73 and 0.64, respectively for mean incontinence score ≥1. Best-fit n values were 0.03-0.05 and 1 for bleeding and incontinence, respectively. The inclusion of clinical factors always improved the predictive value of the models. Conclusions: The inclusion of predisposing clinical factors improves NTCP estimation; the assessment of other clinical and genetic factors will be useful to reduce parameter uncertainties.
AB - Background and purpose: To fit an NTCP model including clinical risk factors to late rectal toxicities after radiotherapy for prostate cancer. Methods and materials: Data of 669 patients were considered. The probability of late toxicity within 36 months (bleeding and incontinence) was fitted with the original and a modified Logit-EUD model, including clinical factors by fitting a subset specific TD 50s: the ratio of TD 50s with and without including the clinical variable was the dose-modifying factor (D mod). Results: Abdominal surgery (surg) was a risk factor for G2-G3 bleeding, reflecting in a TD 50 = 82.7 Gy and 88.4 Gy for patients with and without surg (D mod = 0.94; 0.90 for G3 bleeding); acute toxicity was also an important risk factor for G2-G3 bleeding (D mod = 0.93). Concerning incontinence, surg and previous diseases of the colon were the clinical co-factors. D mod(surg) and D mod(colon) were 0.50 and 0.42, respectively for chronic incontinence and 0.73 and 0.64, respectively for mean incontinence score ≥1. Best-fit n values were 0.03-0.05 and 1 for bleeding and incontinence, respectively. The inclusion of clinical factors always improved the predictive value of the models. Conclusions: The inclusion of predisposing clinical factors improves NTCP estimation; the assessment of other clinical and genetic factors will be useful to reduce parameter uncertainties.
KW - Dose-volume effects
KW - NTCP models
KW - Prostate radiotherapy
KW - Rectal toxicity
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U2 - 10.1016/j.radonc.2011.06.032
DO - 10.1016/j.radonc.2011.06.032
M3 - Article
C2 - 21741721
AN - SCOPUS:80051799886
VL - 100
SP - 124
EP - 130
JO - Radiotherapy and Oncology
JF - Radiotherapy and Oncology
SN - 0167-8140
IS - 1
ER -