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Background: Breast-conserving surgery (BCS) followed by postoperative radiation therapy (RT) to the residual breast represents the current standard of care for most women affected by early breast cancer. However, standard postoperative regimens are characterized by postsurgical waiting time and potential acute and late locoregional adverse events. Several studies suggested that breast cancer cells can be more sensitive to high doses administered in short intervals. Preoperative robotic stereotactic radiotherapy (SBRT) followed by BCS may yield potential advantages in selected patients. An exploratory phase II study (ROCK trial – NCT03520894) was conducted in our institution. Materials: Women with histologically proven unifocal invasive hormonal receptors positive, HER2 negative breast cancer, sized less than 25 mm, with negative clinical nodal status, aged 50+ and eligible for BCS were enrolled. Fiducial markers were introduced in peri/ intralesional position. Magnetic resonance imaging (MRI) was used in addition to standard CT-based planning. Patients received 21 Gy in single fraction with CyberKnife® followed by BCS two weeks after preoperative SBRT. The primary endpoint was the acute skin toxic effect rate. Secondary objectives were the pathological response rate and the late adverse events rate. Echocardiography and spirometry were performed before preoperative SBRT and yearly thereafter. Translational research was conducted to identify correlations between radiogenomic, immunological and biochemical biomarkers with treatment-related response and toxicity. Results: From August 2018 to September 2021, a total of 70 patients were screened on mammography; 29 of them were eligible following inclusion criteria. Seven were excluded due to multiple foci disease at basal MRI, and 22 patients were successfully treated. All required dosimetric parameters and normal tissue constraints were met in all cases. Median age at diagnosis was 68 years (range 50-86) and median tumor size was 13 mm (range 7.5-25). All treated patients received surgery within 14 days from preoperative SBRT without any delay or complication. No patients experienced acute skin toxicity of grade (G) 2 or higher; only one patient had a G1 erythema one month after BCS. Two patients reported a pathological complete response, according to Chevallier’s classification. At a median follow up of 18 months, no patients experienced locoregional recurrence or distant metastases. No clinically meaningful changes were observed regarding left-ventricular ejection fraction and spirometric parameters. Conclusion: Results from the ROCK trial showed that single fraction preoperative robotic SBRT is a feasible technique in selected breast cancer patients with a good safety profile and encouraging activity. This new approach warrants further investigations. [ABSTRACT FROM AUTHOR]

Differentiated thyroid cancer is usually associated with a good prognosis. The development of metastases in Iodine-refractory thyroid cancer adversely affect patients’ quality of life and survival. The advent of tyrosine-kinase inhibitors drugs (TKI) allowed a great improvement of patients’ outcome but, in case of oligometastatic disease, a locoregional ablative approach such as Stereotactic Radiation Therapy (SRT) could effectively control tumour progression and possibly defer the need of systemic therapies. In our study, we analysed the effectiveness of SRT in oligometastatic Iodine-refractory thyroid cancer patients. Methods: We retrospectively analysed patients with differentiated oligometastatic thyroid cancer treated with SRT in our Radiation Oncology Unit from 2011 to 2020. We collected demographics and treatment-related characteristics. Local Control (LC), Progression Free Survival (PFS) and Overall Survival (OS) rates were evaluated. Patients with anaplastic histology, incomplete treatment or without follow-up information were excluded. Results: We retrospective analysed a cohort of 15 patients, aged between 47 and 72 years old (median 63,3). 8 (53,3%) patients were males and 7 (46,7%) were females. A total of 42 lesions were treated: 19 were located in bones (45,2%), 11 in lymph nodes (26,2%), 3 visceral (7.1%), 7 in the brain (16,7%) and 2 in the lungs (4,8%). SBRT was delivered in 1-8 fractions, with a median dose of 30Gy (range 14-60Gy). Median followup from the date of the first SRT was 47,7 months (range 14,4–105 months). After SRT we observed a complete response in 21 lesions (50%), partial response in 13 (31%), stable disease in 7 (16,7%) and only 1 progressive lesion (2,4%). We observed 9 local recurrences (21,4%) with an actuarial LC of 95% and 89,9% at 12 and 24 months respectively, while PFS was 45.6% and 32,9% at 12 and 24 months respectively. The OS at 12, 24, 48 months was 93,3%, 86,2% and 79%, respectively. A total number of 10 patients (66,7%) underwent TKI treatment (4 Sunitinib and 5 Lenvatinib) for progressive disease: median time to first systemic treatment from the SBRT was 17,7 months (range 1-47,7 months). At the end of this analysis, 5 patients (33.3%) were still without systemic therapy, showing a good disease control after a median follow-up of 50,6 months (range 35.3-57). Conclusions: In our experience, SRT yields satisfying local control rates in oligometastatic Iodine-refractory thyroid cancer, allowing for a deferral of systemic therapies. [ABSTRACT FROM AUTHOR]