Multivariate normal tissue complication probability modeling of vaginal late toxicity after brachytherapy for cervical cancer

Abstract : PURPOSE: To explore the best variables combination for a predictive model of vaginal toxicity in cervical cancer patients undergoing brachytherapy (BT). METHODS AND MATERIALS: Clinical and 3-dimensional dosimetric parameters were retrospectively extracted from an institutional database of consecutive patients undergoing intracavitary BT after external beam radiation therapy from 2006 to 2013 for a cervical cancer. A least absolute shrinkage and selection operator selection procedure in Cox's proportional hazards regression model was performed to select a set of relevant predictors for a multivariate normal tissue complication probability model of Grade ≥2 vaginal late toxicity. Outcomes reliability was internally assessed by bootstrap resampling method. RESULTS: One hundred sixty-nine women were included in the present study with a median followup time of 3.8 years (interquartile range [IQR], 1.9-5.6 years). The 2 years and 5 years cumulative incidence rates of Grade ≥2 late vaginal toxicity were 19.9% and 27.5%, respectively. Among 31 metrics and six clinical factors extracted, the optimal model included two dosimetric variables: V70Gy and D5% (the percentage volume that received a dose greater or equal to 70 Gy and the minimum dose given to the hottest 5% volume, respectively). Area under the ROC curve at 2 and 5 years of followup were 0.85 and 0.91, respectively. Regarding internal validation, median area under the ROC curve of bootstrap predictions was 0.83 (IQR, 0.78-0.88) and 0.89 (IQR, 0.85-0.93) at 2 and 5 years of followup, respectively. CONCLUSIONS: A multivariate normal tissue complication probability model for severe vaginal toxicity based on two dosimetric variables (V70Gy and D5%) provides reliable discrimination capability in a cohort of cervical cancer treated with external beam radiation therapy and BT.
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https://www.hal.inserm.fr/inserm-02088828
Contributor : Christine Dupuis <>
Submitted on : Wednesday, April 3, 2019 - 11:15:25 AM
Last modification on : Friday, April 5, 2019 - 1:14:41 AM

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Pierre Annede, Hugues Mailleux, Patrick Sfumato, Marjorie Ferré, Aurélie Autret, et al.. Multivariate normal tissue complication probability modeling of vaginal late toxicity after brachytherapy for cervical cancer. Brachytherapy, Elsevier, 2018, 17 (6), pp.922-928. ⟨10.1016/j.brachy.2018.07.005⟩. ⟨inserm-02088828⟩

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