Session Item

To compare outcomes and toxicity of salvage extended nodal radiotherapy (ENRT) versus Stereotactic body radiotherapy (SBRT) on lymph nodal (LN) relapse in oligometastatic gynecological cancer patients (pts).

From 03/2007 to 10/2021, 53 gynecological cancer patients with LN relapse after previous radical therapies were treated with fluoro-deoxy-glucose positron emission tomography/computed tomography (PET/CT) guided-salvage RT in our Institution: 28 with ENRT+SiB on positive PET/TC LN (group 1) and 25 with SBRT (group 2) on positive PET/TC LN. Primary histology was: ovarian in 20pts, endometrial in 18pts, cervix in 11pts and others in 3pts, almost equally distributed in the two groups. In group 1 two target were defined: the first one included the lymph-nodal chain of interest (pelvic, para-aortic or mediastinal) as clinical target volume (CTV1), adding a 7mm isometric margin to obtain the planning target volume (PTV1). The PTV2 was obtained adding a 5mm isometric margin to GTV-PET. In group 2 the PTV was obtained adding 3 mm isometric margin to GTV-PET. The prescription dose was 50.4Gy/28 fractions (fr) to PTV1 and median dose of 61.01 (50.4-65.5)Gy to PTV2 in group 1, while in group 2 the median dose to PTV was 36 (30-45)Gy in 3-5 fr (6-12Gy/fr). The treatment was delivered with TomoTherapy® or RapidArc® (Varian Medical Systems, Palo Alto, CA) in group 1 and CyberKnife®(Accuray, Sunnyvale, CA) in group 2.

Median follow-up was 32.2 (3.4 – 142.4) and 14.67 (3.2-39.11) months for group 1 and 2, respectively. Acute toxicity were almost negligible in SBRT and mild, in the ENRT group, (see table 1). Loco-regional relapse was registered in 4/28 pts in group 1, while in group 2 relapse in lymph-nodal chain was registered in and 2/25 pts and no recurrence occurred in the single lymph-node treated with SBRT. Systemic progression was observed in 50% of pts in both group (53% vs 48%). Kaplan Meier estimates of 12 months OS were 88% vs 93% (p=0,21), while 12-months DFS was 54 vs 58 % (p=0,99).

In oligometastatic pts lymph-node PET-guided radiotherapy is feasible ensuring good (88.7%) local control. Even considering the limitation due to the difference between the median follow-up, of the two groups, the results seem similar in terms of DFS and OS. ENRT+ SIB toxicity was acceptable but SBRT toxicity was lower. Longer follow-up is necessary to confirm these results.