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Stereotactic body radiation therapy (SBRT) is becoming the treatment of choice for oligometastatic patients (pts) thanks to its fast delivery, low toxicity and high local control rates. The purpose of this retrospective analysis is to evaluate SBRT for oligometastatic lymph-nodal relapses (LNM) in gynecological cancer pts in terms of local control (LC) and toxicity.

From February 2009 to November 2020, 39 LNM in 26 pts were treated with SBRT. Five LNM of 4 pts were treated with helical Image Guided- Intensity Modulated Radiotherapy (IG-IMRT) to a median dose of 54 (35-63) Gy in 6 (5-10) median fractions prescribed to 95% of the Planning Target Volume (PTV). Thirty-four LNM of 22 pts were treated with robotic SBRT to a median dose of 36 (30-45) Gy in a median of 5 (3-5) fractions prescribed at a median isodose of 79% (68-84%). Seven PTVs (18%) were in the same field of previous adjuvant or salvage radiotherapy performed with IG-IMRT with a median dose of 53.2 Gy. The primary cancer was: ovarian in 11 pts (42.3%), endometrial in 10 pts (38.5%), cervical cancer in 4 pts (15.4%) and fallopian tube carcinoma in 1 patient (3.8%). Seventeen (43,6%) LNM locations were periaortic, 8 (20.5%) mediastinal, 8 (20.5%) pelvic, and 6 (15.4%) in other sites (retroclavicular, supraclavicular, axillary, subcostal and inguinal). Gross tumor volume (GTV) was defined by the fusion of CT and PET/CT images in whole pts. Radiological/Nuclear Medicine imaging and clinical follow up were performed every 3 months. Toxicity was assessed using CTCAE version 4.03 criteria.

Median follow-up was 18 months (range 2.2–75.4). All pts completed the prescribed treatment. Nine pts (34.6%) presented grade (G) 1-2 acute toxicity, relative to the irradiate site, as follows: diarrhea (n=2, 7.7%), dysphagia (n=1, 3.8%), esophagitis (n=1, 3.8%) and nausea (n=1, 3,8%). No grade ≥3 acute toxicities was observed. One patient presented late toxicity, a G2 rib pain, persistent 28 months after the end of the treatment. A complete response was observed in 33 lesions (84.5%), partial response in 3 lesions (7.7 %) and progressive disease in 3 lesions (7.7 %), respectively. Three pts (11.5%) had local and distant disease progression, while 15 pts (57.7%) had distant disease progression whit local control.  Two pts died at a median of 70.8 months after the end of the treatment for progressive disease, and one patient died 8.5 months after the treatment due to a second cancer. Disease Free Survival (DFS) was 12.5 months (1.1-67.2).

SBRT in oligometastatic lymph nodal relapse of gynecological tumors showed good local control and a good toxicity profile. It might be an appealing alternative to other invasive local therapies as surgery and could delay or avoid systemic therapy. A longer follow up is needed to confirm these results.