Article Text
Abstract
Introduction MITO-RT3/RAD(NCT04593381) is a prospective multicenter Phase II trial designed to assess the effectiveness and safety of stereotactic radiotherapy(SBRT) in patients diagnosed with oligometastatic ovarian cancer(oligo-MPR-OC).In this report, we provide the results of the trial in the setting of lymph node disease.
Methods The primary endpoint was the complete response(CR) rate,secondary endpoints included local control(LC), progression-free survival(PFS), overall survival(OS), treatment-free interval(TFI),and toxicity rates.Sample size was based on a previous study reporting an average 70.0% CR with SBRT.The study was powered to detect an improvement in the CR rate from 70.0% to 85.0%, with an α error of 0.05 (two-sided) and a β error of 0.1.
Results The study met its primary endpoint of a statistically significant improvement of CR.135 patients with 249 lesions were enrolled across fifteen Institutions from May 2019 to November 2023. CR were observed in 194 lesions(77.9%), PR in 40(16.1%), SD in 14(5.6%), and Progressive Disease(PD) in one lesion(0.4%).The ORR was 94%, with an overall clinical benefit rate of 99.6%. CR lesions exhibited a significantly higher LC rate than partial or not responding lesions(12-month LC: 92.7% vs. 63.1%, p<0.001).The 12- actuarial rates for PFS and for OS were 36.6% and 97.2%,respectively.The 12- actuarial rate for Treatment Free Interval was 52.7%.Twenty-three patients (17.0%) experienced mild acute toxicity. Late toxicity was reported in 9 patients (6.7%), mostly Grade 1.
Conclusion/Implications This trial confirms the efficacy of ablative SBRT, with minimal toxicity observed. SBRT offered a high CR rate, promising long-term outcomes and systemic-therapy-free survival rate for complete responders.