Contribution of intraoperative radiotherapy (IORT) for therapeutic de-escalation in early breast cancer: Report of a single institution's experience.

The spread of systematic screening and the emergence of oncoplastic techniques allow more breast conservative treatment associating lumpectomy and external beam radiation therapy. In order to furthermore facilitate the patient's treatment, intraoperative radiation therapy (IORT) has been developed. The oncological safety of this technique has been studied, and is considered acceptable. Many questions remain unsolved in regard of the toxicity of this procedure as well as the patient's selection criteria. In this study, we present the first results and complications rate of patients treated by IORT in a single French institution. Between 2012 and 2015, all patients with breast cancer treated in a one-step procedure associating lumpectomy and IORT were retrospectively included in a monocentric cohort. Acute and long-term toxicities were evaluated using CTCAE v4.0 classification. 280 breast cancers were treated using IORT procedure. Additional external beam radiation therapy was requested for 45.7% patients. The acute complications rate was 14.6%, with 5 surgical revisions needed (1.78%). With a median follow up of 911 days, the long-term grade-3 toxicity rate was 1.1%. The only risk factor for local fibrosis was external beam radiation therapy (EBRT) (OR = 1.99; IC95 [1.05-3.81], P = 0.036). Three patients (1.07%) were diagnosed with local recurrence. The results from this cohort confirm the low complication and recurrence rate of IORT procedure. A good selection of patients is necessary in order to lower the EBRT rate and allow therapeutic de-escalation. The classification of tumors into IHC subsets seems a good selection gate. Intraoperative radiation therapy appears to have a low toxicity rate with an acceptable local recurrence risk, and should therefore be considered as an option in the treatment of early breast cancer.

[Start of activity with the MRIdian® system: The first 200 patients treated at the Institut Paoli-Calmettes]. / Retour d'expérience clinique à propos des 200 premiers patients traités au MRIdian® à l'Institut Paoli-Calmettes.

INTRODUCTION: Several centers have recently been equipped with MRI-guided radiotherapy systems, including the Paoli-Calmettes Institute which was the first French center to start this activity. We report in this article our early experience. METHODS: Data related to patients treated on the MRIdian® (Viewray®) were prospectively collected. Procedures concerning the implementation of the system and internal organizational issues were summarized. RESULTS: Between February 2019 and March 2020, 201 patients were treated: 40% of treatments were normofractionated (n=70) and 60% used hypofractionation (n=105). The reported monthly occupancy rate at one, six and twelve months was 30%, 62%, and 90%. The distribution of normofractionated treatments was dominated by prostatic (29%) and pancreatic (26%) cancers, followed by abdomino-pelvic irradiations for gynecological cancers (12%) or lymph node diseases (12%) and boosts for rectal or vaginal cancers (11%). Regarding treatments with moderate hypofractionation (dose by fraction between 3 and 5Gy), they corresponded mainly to integrated boost for abdomino-pelvic lymph nodes (38%), while the stereotaxic treatments primarily concerned hepatic lesions (15%), bones (30%). DISCUSSION: The MRIdian® was initially used widely in our service corresponding to a learning curve for MRI guidance. This new tool for image-guided radiotherapy helped us to secure our practice providing solutions for both inter and intra-fraction movements making it possible to reduce the additional margin in order to better protect the organs at risk. The main technical difference with conventional accelerators is the possibility of performing adaptive radiotherapy in real time, the start of which was more gradual.

External validation of a published nomogram for prediction of brain metastasis in patients with extra-cerebral metastatic breast cancer and risk regression analysis.

BACKGROUND: Survival of patients with metastatic breast cancer (MBC) suffering from brain metastasis (BM) is limited and this event is usually fatal. In 2010, the Graesslin's nomogram was published in order to predict subsequent BM in patients with breast cancer (BC) with extra-cerebral metastatic disease. This model aims to select a patient population at high risk for BM and thus will facilitate the design of prevention strategies and/or the impact of early treatment of BM in prospective clinical studies. PATIENTS AND METHODS: Nomogram external validation was retrospectively applied to patients with BC and later BM between January 2005 and December 2012, treated in our institution. Moreover, risk factors of BM appearance were studied by Fine and Gray's competing risk analysis. RESULTS: Among 492 patients with MBC, 116 developed subsequent BM. Seventy of them were included for the nomogram validation. The discrimination is good (area under curve = 0.695 [95% confidence interval, 0.61-0.77]). Risk factors of BM appearance are: human epidermal growth factor receptor 2 (HER2) overexpression/amplification, triple-negative BC and number of extra-cerebral metastatic sites (>1). With a competing risk model, we highlight the nomogram interest for HER2+ tumour subgroup exclusively. CONCLUSION: Graesslin's nomogram external validation demonstrates exportability and reproducibility. Importantly, the competing risk model analysis provides additional information for the design of prospective trials concerning the early diagnosis of BM and/or preventive treatment on high risk patients with extra-cerebral metastatic BC.