Late hepatic toxicity after breast cancer intensity-modulated radiotherapy using helicoidal tomotherapy

Purpose. - Helical tomotherapy (HT) is a rotational intensity-modulated radiation therapy (IMRT) tech-nique that allows target conformal irradiation and efficient organs at risk (OAR) sparing in the case of complex target volumes and specific anatomic considerations, but increases the "low-dose bath" to non -target volumes. The aim of this study was to analyze the delayed hepatotoxicity after rotational IMRT (HT) radiation therapy for non-metastatic breast cancer. Patients and methods. - This single-center retrospective study included all non-metastatic breast cancer patients with a normal pre-radiotherapy biological hepatic function who were treated with tomotherapy between January 2010 and January 2021 and for whom the dosimetric parameters for the whole liver were assessable. A logistic regression analysis was employed. The selected covariates for the multivariate analysis were those with a P-value that was less or equal to 0.20 in the univariate analysis. Results. - Forty-nine patients were included in this study: 11 patients (22%) received Trastuzumab for 1 year in tumors with an HER2-expression; 27 patients (55%) received radiation therapy for cancer of the right or bilateral breasts; 43 patients (88%) received lymph node irradiation and 41 patients (84%) received a tumor bed boost. Mean and maximum doses to the liver were 2.8 Gy [0.3-16.6] and 26.9 Gy [0.7-51.7], respectively. With a median follow-up after irradiation was 5.4 years (range, 6 to 115 months), 11 patients (22%) had developed delayed low grade biological hepatic abnormalities: all patients had grade 1 delayed hepatotoxicity; 3 patients (6%) had additional grade 2 delayed hepatotoxicity. There was no hepatotoxicity at grade 3 or higher. According to the univariate and multivariate analysis, Trastuzumab was a significant predictive variable of late biological hepatotoxicity (OR = 4.4 [1.01-20.18], P = 0.04). No other variable was statistically associated with delayed biological hepatotoxicity. Conclusion. - Delayed hepatotoxicity after multimodal non-metastatic breast cancer management includ-ing rotational IMRT was negligible. Consequently, the liver doesn't have to be considered like an organ-at-risk in the analysis of breast cancer radiotherapy but future prospectives studies are needed to confirm these findings. & COPY; 2023 Societe franc,aise de radiotherapie oncologique (SFRO). Published by Elsevier Masson SAS. All rights reserved.