Developing a multivariable normal tissue complication probability model to predict late rectal bleeding following intensity-modulated radiation therapy

Abstract

Purpose : To develop a multivariable normal tissue complication probability (NTCP) model to predict moderate to severe late rectal bleeding following intensity-modulated radiation therapy (IMRT). Methods and materials : Sixty-eight patients with localized prostate cancer treated by IMRT from 2008 to 2011 were enrolled. The median follow-up time was 56 months. According to the criteria of D'Amico risk classifications, there were 9, 20 and 39 patients in low, intermediate and high-risk groups, respectively. Forty-two patients were combined with androgen deprivation therapy. Fifteen patients had suffered from grade 2 or more (grade 2+) late rectal bleeding. The numbers of predictors for a multivariable logistic regression NTCP model were determined by the least absolute shrinkage and selection operator (LASSO). Results : The most important predictors for late rectal bleeding ranked by LASSO were platelet count, risk group and the relative volume of rectum receiving at least 65 Gy (V 65 ). The NTCP model of grade 2+ rectal bleeding was as follows: S = -17.49 + Platelets (1000/μL) * (-0.025) + Risk group * Corresponding coefficient (low-risk group = 0; intermediate-risk group = 19.07; high-risk group = 20.41) + V 65 * 0.045. Conclusions : A LASSO-based multivariable NTCP model comprising three important predictors (platelet count, risk group and V 65 ) was established to predict the incidence of grade 2+ late rectal bleeding after IMRT.

Prostat Kanserinde Normal Doku Komplikasyon Olasılığının Hesaplanması ve Geç Yan Etkiler

“…Konformal radyoterapi tekniklerinin kullanımıyla üç boyutlu olarak görülebilen tümör ve çevre organ volümlerinde, tedavi planı ile elde edilen organlara ait doz ve volüm ilişkisini gösteren histogramlar klinisyenlere doz dağılımlarını ayrıntılı inceleme olanağı sağlamıştır. Bir çok araştırmacı elde edilen bu doz ve volüm parametreleri ile risk altında kalan çevre organlardaki normal doku hasarı arasında ilişki kurarak çeşitli modeller geliştirmişlerdir (10,18,(25)(26)(27). Bu modeller fiziksel ve matematiksel parametrelerden faydalanılarak kesin olmayan organ tolerans tahminlerine dayandırılmaktadır.…”

“…Tedavilere bağlı komplikasyonlar, olguların uzun yaşam süreleri nedeniyle daha önemli hale gelmiştir. Radyoterapi, lokalize prostat kanseri tedavisinde ana tedavi modalitelerindendir (10). Radyoterapide, son yıllardaki teknik gelişmeler sayesinde daha düşük komplikasyon oranları ve daha yüksek tümör kontrolü hedefi sağlanabilmektedir.…”

Normal tissue complication probability models for prospectively scored late rectal and urinary morbidity after proton therapy of prostate cancer

“…This again indicates that EUD may not be a good predictor of rectal bleeding in this study. Several recent NTCP models have used a logistic regression where more and different predictors have been included (in particular clinical predictors) [16,[36][37][38][39][40][41][42][43] often resulting in better AUC values.…”

Salvage Radiotherapy Plus Androgen Deprivation Therapy for High-Risk Prostate Cancer with Biochemical Failure after High-Intensity Focused Ultrasound as Primary Treatment

“…All patients received SRT by using the technique of intensity modulated technique (IMRT). The technique of IMRT for prostate cancer in the institute has been published [ 11 ]. Sequential two treatment phases were given.…”