S1174
Clinical - Urology
ESTRO 2026
Material/Methods: A retrospective analysis was conducted on patients with biopsy-confirmed renal cancer treated with SMART between 2020 and 2025. All patients received ablative doses (total dose: 35–40 Gy) in 5 fractions (7-8 Gy/fr) , prescribed at 80% isodose level to renal lesions (PTV = GTV + 3mm), delivered using a hybrid MR-linac system. Adaptive planning, consisting in daily on-table replanning to control interfractional volume changes, and real-time motion management were used to optimize precision and minimize exposure to adjacent organs of interest. Radiological treatment response was assessed according to RECIST 1.1 criteria. As secondary outcome, acute adverse events were graded using CTCAE v5.0. Follow-up included serial clinical and imaging evaluations with contrast- enhanced CT. Results: Eleven patients with histologically confirmed renal cancer were included. Median age was 85 years (range: 78-90). At a median follow-up of 6 months (range 3–9), all patients achieved a partial response, with no evidence of local progression. The median tumor size reduction was 30% (range: 20–50%), as illustrated in Figure 1. Renal function remained stable with no significant decline in estimated glomerular filtration rate (eGFR) observed post-treatment. Acute adverse events were mild (Grade 1), including fatigue in 30% of patients and transient hematuria (10%); no Grade ≥ 3 side effects were reported.
consequence of a SM [HRPCa 110/155 (71.0%) vs IRPCa 91/138 (65.9%), p=0.35]. SM represents 24.9% (201/806) of all causes of death. SM occurred at a median age of 78.6 years (interquartile range (IQR): 73.6-82.5). From randomization, the median time to develop a SM was 7.6 years (IQR: 4.6 – 11.4) and was similar for both groups. Of the 201 pts who developed SM and died from it, 38,8% were of a respiratory origin, 29.4% gastrointestinal (GI) , 11.9% genitourinary, 9.5% hematologic, and 10.4% others. SM represent the most frequent cause of death followed by cardiovascular deaths in 12.8%, while 9.8% (121/1230) died from prostate cancer (HRPCa 13.3% vs IRPCa 6.2%, p<0.001). In a multivariate Cox regression analysis over the entire period of follow up time, the occurrence of SM was highly significant to predict time to death [HR (95% CI) = 1.67 (95% CI 1.44-1.94), p<0.001], in addition to older age [HR=1.06 (95% CI 1.05-1.07), p<0.001], HRPCa vs IRPCa [HR=1.37 (95% CI 1.19-1.58), p<0.001], Zubrod (p=0.004) and by the presence of medical comorbidities (p between 0.05 and <0.001). Conclusion: In localised prostate cancer, in pts treated with RT ± ADT , close to a quarter will die from a second malignancy, the leading cause of death. Considering this major impact on prostate cancer survivorship, appropriate surveillance, prevention and education strategies are needed. Keywords: Prostate cancer, second malignancies, death Digital Poster 1167 Stereotactic MR-guided ablative radiotherapy (SMART) for primary and recurrent renal lesions: a monoinstitutional retrospective study Alessandra Castelluccia 1,2 , Domenico Marchesano 1 , Gianmarco Grimaldi 1 , Giuseppina Chiarello 1 , Ivan Annessi 1 , Federico Bianciardi 1 , Annamaria Dipalma 1 , Maria Valentino 1 , Laura Verna 1 , Piercarlo Gentile 1 1 Radiotherapy, San Pietro FBF Hospital, Rome, Italy. 2 Radiotherapy, Perrino Hospital, Brindisi, Italy Purpose/Objective: Localized kidney cancer is primarly managed by surgical resection, the current standard of care. Advances in MR-guided radiotherapy have introduced a precise, non-invasive alternative that enables real- time visualization and motion management. Stereotactic MR-guided ablative radiotherapy (SMART) is an emerging technique providing high-dose radiation delivery with excellent targeting accuracy and optimal tissue sparing. This single-institution study evaluates the efficacy and safety of SMART for primary and recurrent renal tumor.
Conclusion: SMART appears to be a safe, feasible and effective non-invasive treatment option for patients with primary renal tumor, achieving promising short-term local control and minimal acute side effects. These preliminary results suggest that SMART allows for effective tumor ablation while preserving renal function, offering a potential non-surgical alternative, especially for elderly patients and those who are unfit for surgery. Prospective multicentre trials with longer follow-up are warranted to validate these preliminary results.
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