STEREOTACTIC ABLATIVE RADIOTHERAPY FOR OLIGOMETASTATIC OVARIAN CANCER LYMPH NODE DISEASE: THE MITO-RT3/RAD PHASE II TRIAL: stereotactic radiotherapy for ovarian cancer nodal metastases

• Published in: International journal of radiation oncology, biology, physics
• Main Authors: Macchia, Gabriella, Campitelli, Maura, Pezzulla, Donato, Lucci, Simona, Fodor, Andrei, Russo, Donatella, Balcet, Vittoria, Bonome, Paolo, Durante, Stefano, Draghini, Lorena, Titone, Francesca, D'Agostino, Giuseppe Roberto, Tamburo, Marinella, Ferioli, Martina, Ippolito, Edy, Tortoreto, Francesca, Caravatta, Luciana, De Felice, Francesca, Stefano, Aida Di, Fanelli, Mara, Cilla, Savino, Cosentino, Francesco, Marchetti, Claudia, Salutari, Vanda, Boccia, Serena, Morganti, Alessio Giuseppe, Gambacorta, Maria Antonietta, Fagotti, Anna, Pignata, Sandro, Scambia, Giovanni, Ferrandina, Gabriella, Deodato, Francesco
• Format: Journal Article
• Language: English
• Published: United States 24.09.2024
• Subjects: Oligorecurrences; Stereotactic body radiotherapy; Metastases directed therapy; Oligometastasis; Personalized medicine; Lymph nodes; Ovarian cancer
• ISSN: 1879-355X

MITO-RT3/RAD (NCT04593381) is a prospective multicenter Phase II trial designed to assess the effectiveness and safety of stereotactic body 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. 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 (one-side) and a β error of 0.1. 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-months actuarial rates for PFS and for OS were 36.6% (CR 38.3% vs not-CR 18.8%; p: 0.022) and 97.2% (CR 97.8% vs not-CR 93.8%; p: 0.067), respectively. The 12-months actuarial rate for Treatment Free Interval was 52.7% (CR 58.4% vs not-CR 24.4%; p: 0.004). CR was substantially associated with higher PFS (p: 0.036) and TFI (p: 0.006) rates at the univariate analysis. Twenty-three patients (17.0%) experienced mild acute toxicity. Late toxicity was reported in 9 patients (6.7%), mostly Grade 1. 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.