Phase II trial of robotic stereotactic radiosurgery (SBRT) in patients with recurrent gynecologic malignancies.

Abstract

5102 Background: Ablative radiation dose delivered by a robotic SBRT platform has shown progression-free survival benefit in two limited case series among patients with recurrent gynecological malignancies. The therapeutic impact of SBRT on disease progression (PD) was evaluated in the recurrent setting in this phase II trial. Methods: Fifty patients with recurrent and measurable gynecologic malignancy were treated with SBRT. The cohort included patients with recurrent ovarian (n =25), endometrial (n =14), cervical (n =9), or vulvar (n =2) cancer, 1 prior chemotherapy or radiation regimen, and GOG performance status 0, 1, 2. Patients underwent image-guided SBRT in 3 daily doses of 800 cGy = 2400 cGy. SBRT planning target volumes were determined by both the radiation and gynecologic oncologist using non-contrasted CT and 18F-FDG PET/CT overlays. The primary endpoints were 6-month clinical benefit rate (# complete response + # partial response + # stable disease without PD [by RECIST v1.0] / 50), and less than 30-day posttherapy toxicity. Results: Between July 2009 and September 2011, 50 patients were enrolled and have a median posttherapy follow-up of 9 months. At 3 months, 50% (n=25) had complete response, 46% (n=23) had partial response, and 4% (n=2) had stable disease in SBRT-targeted lesions. Twenty-six patients (52%) have had non-SBRT target PD and 18 (36%) have died of PD. Of the 50 patients, 33 had a PD-free interval of at least 6 months, for an overall clinical benefit rate of 66%. Less than 30-day posttherapy SBRT-related toxicities were grade 2 fatigue (n =9 [18%]), grade 2 nausea (n =3[6%], grade 3 nephropathy (n =2[4%]), and grade 4 hyperbilirubinemia (n =1[2%]). Conclusions: This is the first phase II clinical trial of SBRT showing a clinically relevant benefit of ablative radiation in the setting of recurrent gynecological disease. Despite excellent control of targeted lesions with minimal toxicity, non-SBRT target PD rates are high, spurring interest for future SBRT-chemotherapy clinical trials.