Stereotactic Ablative Radiotherapy (SABR) for Oligometastatic Gynecologic Malignancies: A Single Institution Experience

Abstract

<h3>Purpose/Objective(s)</h3> There is a paucity of data regarding use of SABR for gynecologic malignancies. This retrospective analysis was performed to evaluate the feasibility and efficacy of this treatment for this patient population. <h3>Materials/Methods</h3> 20 patients requiring 30 sites of treatment were treated at our institution. 10 patients had endometrial cancer (50%), 9 patients had ovarian cancer (45%) and 1 patient had cervical cancer (5%). 20 sites (67%) were treated with volumetric modulated arc therapy and 10 sites (33%) were treated with dynamic three-dimensional arc therapy. Sites treated included pelvic or abdominal lymph nodes (67%), neck or axillary nodes (13%), bone (10%), lung (7%), and mediastinal nodes (3%). Dose delivered was 30 Gy in 5 fractions (57%), 24-27 Gy in 3 fractions (33%), or 45-50 Gy in 5 fractions (10%). <h3>Results</h3> Median follow-up was 19 months. Grade 3-4 toxicity was not observed in any patients. Progression was defined as requiring a systemic treatment change or requiring another course of SABR. At the time of last follow-up, 10 patients (50%) had progressed. 6 patients (30%) required a change in systemic treatment. True in-field recurrence was not observed in any patients. Median progression free survival was 9.5 months. Median overall survival was not reached. 5 patients (25%) required no systemic therapy of any kind to maintain disease-free status. <h3>Conclusion</h3> SABR was well tolerated and associated with excellent local control. The use of SABR allowed many patients to delay change in systemic treatment, or to avoid systemic treatment altogether. The median progression free survival of 9.5 months in this cohort compares favorably to that expected with second- or third-line systemic therapy (4.1 and 1.7 months, respectively, for ovarian cancer). SABR should be strongly considered for patients with oligometastatic gynecologic malignancies.