Purpose: The results of stereotactic body radiation therapy (SBRT) for parenchymal lesions in the setting of oligometastatic ovarian cancer are reported in the context of the prospective multicenter phase 2 MITO-RT3/RAD trial (NCT04593381). Methods and Materials: The primary endpoint was the complete response (CR) rate, secondary endpoints included local control (LC), progression-free survival, overall survival, treatment-free interval, and toxicity rates. Sample size was based on a previous study reporting an average 40.0% CR with SBRT. The study was powered to detect an improvement in the CR rate from 40.0% to 55.0%, with an α error of 0.05 (one-side) and a β error of 0.1. Results: The study met its primary endpoint of a statistically significant improvement of CR. A total of 88 patients with 127 lesions were enrolled across 15 institutions from May 2019 to November 2023. CRs were observed in 71 lesions (55.9%), partial response in 37 (29.1%), stable disease in 14 (11.0%), and progressive disease in 5 lesions (4.0%). The objective response rate was 85.0%, with an overall clinical benefit rate of 96.0%. The overall 12-month LC was 81.6%, with CR lesions exhibiting a significantly higher rate than partial or not responding lesions (12-month LC: 96.3% vs 61.4%, P < .001). The 12-month actuarial rates for progression-free survival and for overall survival were 34.9% and 91.5%, respectively. The median actuarial treatment-free interval was 9 months (range, 2.5-15.4 months), whereas the 12-month actuarial rate was 44.1%. No grade 3 or higher toxicity was reported. In particular, 15 (20.5%) patients experienced mild acute toxicity (≤grade 2). There were 12 grade 1 events and 6 grade 2 events, the latter mostly represented by pain flare (N = 2). Late toxicity was reported in 4 patients (4.5%) accounting for 4 events, mostly grade 1, except for one case of moderate asthenia (grade 2). Conclusions: Parenchymal oligometastatic lesions showed a high rate of CR and encouraging long-term outcomes for patients achieving CR, including a substantial period of systemic therapy-free survival after radiation therapy. The observed toxicity was minimal, strengthening the safety of ablative SBRT as a noninvasive alternative to surgical resection for parenchymal metastases in high-risk areas.
Macchia, G., Pezzulla, D., Campitelli, M., Lucci, S., Draghini, L., Russo, D., Fodor, A., D'Agostino, G. R., Balcet, V., Tamburo, M., Giaccherini, L., Tortoreto, F., Augurio, A., Ippolito, E., Stefano, A. D., Fanelli, M., Petrella, L., Cilla, S., Cosentino, F., Marchetti, C., Salutari, V., Morganti, A. G., Gambacorta, M. A., Fagotti, A., Pignata, S., Scambia, G., Ferrandina, M. G., Deodato, F., Treatment of Oligometastatic Parenchymal Lesions in Ovarian Cancer With Stereotactic Ablative Radiation Therapy: A Multicenter Prospective Phase 2 Trial (MITO RT3/RAD), <<INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS>>, 2025; 123 (1): 228-237. [doi:10.1016/j.ijrobp.2025.03.032] [https://hdl.handle.net/10807/326094]
Treatment of Oligometastatic Parenchymal Lesions in Ovarian Cancer With Stereotactic Ablative Radiation Therapy: A Multicenter Prospective Phase 2 Trial (MITO RT3/RAD)
Macchia, Gabriella;Campitelli, Maura;Cilla, Savino;Marchetti, Claudia;Salutari, Vanda;Morganti, Alessio Giuseppe;Gambacorta, Maria Antonietta;Fagotti, Anna;Scambia, Giovanni;Ferrandina, Maria Gabriella;Deodato, Francesco
2025
Abstract
Purpose: The results of stereotactic body radiation therapy (SBRT) for parenchymal lesions in the setting of oligometastatic ovarian cancer are reported in the context of the prospective multicenter phase 2 MITO-RT3/RAD trial (NCT04593381). Methods and Materials: The primary endpoint was the complete response (CR) rate, secondary endpoints included local control (LC), progression-free survival, overall survival, treatment-free interval, and toxicity rates. Sample size was based on a previous study reporting an average 40.0% CR with SBRT. The study was powered to detect an improvement in the CR rate from 40.0% to 55.0%, with an α error of 0.05 (one-side) and a β error of 0.1. Results: The study met its primary endpoint of a statistically significant improvement of CR. A total of 88 patients with 127 lesions were enrolled across 15 institutions from May 2019 to November 2023. CRs were observed in 71 lesions (55.9%), partial response in 37 (29.1%), stable disease in 14 (11.0%), and progressive disease in 5 lesions (4.0%). The objective response rate was 85.0%, with an overall clinical benefit rate of 96.0%. The overall 12-month LC was 81.6%, with CR lesions exhibiting a significantly higher rate than partial or not responding lesions (12-month LC: 96.3% vs 61.4%, P < .001). The 12-month actuarial rates for progression-free survival and for overall survival were 34.9% and 91.5%, respectively. The median actuarial treatment-free interval was 9 months (range, 2.5-15.4 months), whereas the 12-month actuarial rate was 44.1%. No grade 3 or higher toxicity was reported. In particular, 15 (20.5%) patients experienced mild acute toxicity (≤grade 2). There were 12 grade 1 events and 6 grade 2 events, the latter mostly represented by pain flare (N = 2). Late toxicity was reported in 4 patients (4.5%) accounting for 4 events, mostly grade 1, except for one case of moderate asthenia (grade 2). Conclusions: Parenchymal oligometastatic lesions showed a high rate of CR and encouraging long-term outcomes for patients achieving CR, including a substantial period of systemic therapy-free survival after radiation therapy. The observed toxicity was minimal, strengthening the safety of ablative SBRT as a noninvasive alternative to surgical resection for parenchymal metastases in high-risk areas.
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