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.
Treatment of Oligometastatic Parenchymal Lesions in Ovarian Cancer With Stereotactic Ablative Radiation Therapy: A Multicenter Prospective Phase 2 Trial (MITO RT3/RAD)
Ippolito, Edy;
2025-01-01
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
