正常组织并发症概率（NTCP）模型对于估计乳腺保留手术（BCS）和放疗（RT）后纤维化风险具有一定的实用性。然而，这些模型存在不确定性。我们研究了轮廓变化对于纤维化预测的影响。我们纳入了280例接受BCS-RT治疗的乳腺癌患者。针对每位患者创建了九个临床靶体积（CTV）轮廓：i）CTV_crop（参考），从皮肤上裁剪5mm；ii）CTV_skin，未裁剪且包括皮肤；iii）分割95%等剂量（Iso95%）；iv）三个不同的自动分割辅助图集生成未裁剪和裁剪的轮廓（Atlas_skin/Atlas_crop）。为了说明轮廓变化对NTCP估计的影响，我们分别将两个方程（基于Lyman-Kutcher-Burman（LKB）和相对序列（RS）模型）应用于每个轮廓，以预测5年内纤维化分级≥2。使用重复测量ANOVA进行了差异评估。为了完整起见，还使用logistic回归评估了观察到的纤维化事件与NTCP估计之间的关联。在相同的轮廓方法（裁剪和未裁剪）下，轮廓之间的差异很小。与CTV_crop相比，CTV_skin和Atlas_skin轮廓的NTCP估计较低（-3.92%，IQR 4.00，p <0.05）。与CTV_crop相比，Atlas_crop和Iso95%轮廓没有显著差异。对于整个队列，根据所选轮廓的不同，LKB模型的NTCP估计值在5.3%至49.5%之间变化，RS模型的NTCP估计值在2.2%至49.6%之间变化。个体患者的NTCP估计值最多相差四倍。来自“皮肤”轮廓的估计值与观察到的事件之间显示出更高的一致性。轮廓变异可能导致乳腺纤维化的NTCP估计值存在显著差异，凸显了在开发和/或应用NTCP模型之前标准化乳腺轮廓的重要性。版权所有 © 2023 Elsevier Ltd. 发布。

Normal tissue complication probability (NTCP) models can be useful to estimate the risk of fibrosis after breast-conserving surgery (BCS) and radiotherapy (RT) to the breast. However, they are subject to uncertainties. We present the impact of contouring variation on the prediction of fibrosis.280 breast cancer patients treated BCS-RT were included. Nine Clinical Target Volume (CTV) contours were created for each patient: i) CTV_crop (reference), cropped 5 mm from the skin and ii) CTV_skin, uncropped and including the skin, iii) segmenting the 95% isodose (Iso95%) and iv) 3 different auto-contouring atlases generating uncropped and cropped contours (Atlas_skin/Atlas_crop). To illustrate the impact of contour variation on NTCP estimates, we applied two equations predicting fibrosis grade ≥ 2 at 5 years, based on Lyman-Kutcher-Burman (LKB) and Relative Seriality (RS) models, respectively, to each contour. Differences were evaluated using repeated-measures ANOVA. For completeness, the association between observed fibrosis events and NTCP estimates was also evaluated using logistic regression.There were minimal differences between contours when the same contouring approach was followed (cropped and uncropped). CTV_skin and Atlas_skin contours had lower NTCP estimates (-3.92%, IQR 4.00, p < 0.05) compared to CTV_crop. No significant difference was observed for Atlas_crop and Iso95% contours compared to CTV_crop. For the whole cohort, NTCP estimates varied between 5.3% and 49.5% (LKB) or 2.2% and 49.6% (RS) depending on the choice of contours. NTCP estimates for individual patients varied by up to a factor of 4. Estimates from "skin" contours showed higher agreement with observed events.Contour variations can lead to significantly different NTCP estimates for breast fibrosis, highlighting the importance of standardising breast contours before developing and/or applying NTCP models.Copyright © 2023. Published by Elsevier Ltd.