Efficacy and Safety of SBRT in Oligo-metastatic/Persistent/Recurrent Ovarian Cancer

Stereotactic Body Radiotherapy (SBRT) represents the cutting edge within high conformal and modulated radiotherapy techniques; it can provide high local control (LC) for curative-intent of low burden metastatic, persistent and metastatic lesions in face of minimal acute and late toxicities. SBRT is amenable even in patients who had already been managed by radiotherapy. In addition, SBRT has been shown to be active in chemoresistant disease, and potentially able to mount immune response through the release of tumor neoantigens after cell killing, thus allowing to synergize with immunotherapeutic approaches. SBRT has been widely adopted in the clinical setting of oligometastatic/persistent/recurrent (MPR) disease (up to <5 lesions) in several malignancies including also ovarian cancer (OC); the recently published retrospective, multicenter Italian study (MITO-RT1) has confirmed the activity and safety of SBRT in MPR OC, thus providing a model able to predict the higher chance of complete response of tumor lesions to SBRT, and local control rate.

The MITO-RT3/RAD trial is a prospective, Italian multicenter Phase II study aimed at evaluating the activity and safety of SBRT in MPR-OC patients. Clinical and imaging data, as well as SBRT technical parameters, would be analyzed with the aim to identify potential predictors of response to treatment and clinical outcome: in this context, additional insights into the tissue features of tumor lesions would be of clinical interest in the context of the personalized treatment, as testified by studies demonstrating that image-based quantitative features from pre-treatment imaging could predict clinical outcomes in several malignancies.

Furthermore, given the crucial role played by the mutational status of BRCA 1/2 genes in this disease, the assessment of BRCA gene status was considered mandatory, thus representing inclusion criteria.

The study will include patients with oligo-metastatic/persistent/recurrent lesions (MPR) from OC patients for which salvage surgery or other local therapies resulted not feasible, as per relative contraindication to further systemic therapy because of serious comorbidities, as per previous severe toxicity, unavailability of potentially active chemotherapy, or patient refusal of systemic therapy

Inclusion criteria

• diagnosis of ovarian cancer
• age >18 yrs,
• ECOG performance status 0-3,
• expected life expectancy >6 months,
• 1-5 synchronous lesions
• any site of disease,
• compulsory assessment of mutational status of BRCA1/2 genes (either germline or somatic),
• salvage surgery or other local therapies not feasible,
• relative contraindication to further systemic therapy because of serious comorbidities,
• previous severe systemic therapy toxicity
• unavailability of potentially active systemic therapy,
• patient refusal of systemic therapy,
• Re-treatment of lesions already treated with conventional external beam radiotherapy is allowed*

Exclusion criteria

• mucinous OC,
• borderline ovarian tumors,
• non-epithelial OC,
• previous radiotherapy severe toxicity
• co-morbidities and functional impairment considered clinically precluding the safe use of SBRT,
• pregnancy
• any psychological, sociological, or geographical issue potentially hampering compliance with the study,
• lesion diameter larger than 5 centimeters