ESTRO 2021 Abstract Book

S1064

ESTRO 2021

analyzed. Overall survival (OS), Local control rate (LC) and Disease free survival (DFS) were plotted using the Kaplan-Meier methods. The log-rank test and cox regression model were used to assess the differences in survival due to stage and pathological diagnosis. EQD2 dose to point A (α/β=10) and rectum (α/β=3) were also assessed to see the effect on dosing to point A and rectum in reference to efficacy of the treatment as well as late adverse effect. Results One hundred seventy-eight patients were evaluated. Their median age was 52 (range: 28-79) years. The median follow up time was 53.5 (range: 1-159) month. The number of patients with FIGO ≦ IIA and ≧ IIB were 29(16.3%) and 149(83.7%), respectively. The number of patients with squamous cell carcinoma (SCC), adenocarcinoma, adeno-squamous carcinoma, and other were 158 (88.8%), 13(7.3%), 5(2.8%), and 2(1.2%), respectively. One hundred thirty-three patients (74.7%) have completed the planned 5 courses of PF. Median EQD2 dose to point A (α/β=10) and rectum (α/β=3) were 71.3 (range: 55.8-91.1)Gy and 67 (range: 45.4-87.2) Gy, respectively. The 5-year OS, LC, and DFS in all patients were 75.6%, 91%, and 67%, respectively. The 5- year OS in patients with FIGO ≦ IIA and ≧ IIB were 90% and 72%, respectively. The 5-year OS in patients with SCC and other pathology were 78% and 57%, respectively. Multivariate analysis showed worse OS in patients with FIGO ≧ IIB (HR, 4.52; 95%CI, 1.09-18.8; p=0.04)and pathology other than SCC (HR, 3.44; 95%CI, 1.63-7.27; p<0.01). No relation in regard to EQD2 to point A and survival were captured. As for late adverse events, one patient has died of perforation of small intestine. She had rheumatism and was taking steroids for long. There were no other treatment related death. Only 3 (1.7%) patients had ≧ G3 rectum bleeding and 3 (1.7%) patients had ≧ G3 bladder bleeding. Conclusion In our study, we were able to control locally advanced cervical cancer even at relatively low doses (median EQD2 71Gy) to point A. The administration of high dose PF may have contributed to this result. In addition, SCC is actively treated with CRT at our hospital, which may also have contributed to this favorable result. PO-1292 Results of two interventional radiotherapy (brachytherapy) schedules for endometrial cancer V. Lancellotta 1 , G. Macchia 2 , A. Salvati 1 , L. Di Maio 1 , E. Placidi 1 , P. Cornacchione 3 , R. Autorino 1 , M. Campitelli 1 , B. Fionda 1 , A. Nardangeli 1 , C. Casà 1 , M. Ferioli 4 , N. Di Napoli 1 , G. Scambia 5 , L. Tagliaferri 1 1 Fondazione Policlinico Universitario “A. Gemelli” IRCCS, UOC Radioterapia Oncologica, Roma, Italy, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, Rome, Italy; 2 Gemelli Molise Hospital, Università Cattolica del Sacro Cuore, Campobasso, Italy., Radiation Oncology Unit, Campobasso, Italy; 3 Fondazione Policlinico Universitario “A. Gemelli” IRCCS, UOC Radioterapia Oncologica, Roma, Italy, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, rome, Italy; 4 Radiation Oncology Center, , DIMES Univerisity of Bologna, Bologna, Italy., Department of Experimental, Diagnostic and Specialty Medicine, Bologna, Italy; 5 Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy; , Department of Woman and Child Health and Public Health, Woman Health Area, Rome, Italy Purpose or Objective To evaluate the late toxicity rate and the clinical outcomes after two different high dose rate (HDR) vaginal interventional radiotherapy (IRT, brachytherapy) schedules in postoperative stage I-II endometrial cancer. Materials and Methods Between 2014 and 2020, 114 low-intermediate-risk Stage I and 3 Stage II patients, median age 62 (32-85) years, underwent surgery, with or without lymphadenectomy, and HDR-IRT: Group 1 was treated by 7 Gy prescribed at 5 mm depth from applicator surface, along 3 week (1 fraction/week) and Group 2 was treated by 6 Gy at 5 mm depth from applicator surface, along 4 week (1 fraction/week). Groups were well-matched with no differences in terms of HDR-IRT techniques, clinical target volumes and point prescription dose. Vaginal toxicity as well as other acute and late toxicities were registered during follow up evaluation according to CTCAE 5.0 scale. The impact of clinical covariates (age, lymphadenectomy, fractionation, stage) on toxicity was evaluated by Pearson correlation test and in multivariate fashion by logistic regression. Results Details on patient’s characteristics are reported in Table 1. The median follow up was 57 (range 40-76) and 17 (range 8-42) months for Group 1 and Group 2, respectively. Vaginal late toxicity was recorded in 40 patients (Group 1) and 15 patients (Group 2), respectively. In the Group 1, one vaginal stenosis G3, two G2, and 12 G1 were recorded, while 2 vaginal dryness G2 and 21 G1 were registered, respectively. Teleangectasia G1 was reported in 2 patients. In the Group 2, one vaginal stenosis G2, and one G1 were reported, while 9 vaginal dryness G1 and two G2 were registered, respectively. Teleangectasia G1 was reported in 2 patients. Univariate analysis of variables predicting vaginal toxicity showed that age, lymphadenectomy, and radiotherapy fractionation (p-value = 0.029, 0.006, 0.002) were significantly associated with a higher probability of develop late vaginal toxicity. After stepwise logistic regression only age and fractionation were found significantly correlated (p-value = 0.02, 0.001). One hundred-six patients were disease free, 10 had a relapse (5 in Group 1 and 5 in Group 2), 1 deceased from disease (Group 1), and 2 from other causes (Group 1). Four vaginal cuff (3.4%), 2 nodal (1.7%) and 6 (5.2%) distant recurrences were registered. The 3-year local-relapse free, distant metastasis-free and cause-specific survival for all patients were 96.6% (95% confidence interval [CI]: 88.1-96.7), 94.8% (95% CI: 93.2-99.3), and 99.1% (95% CI: 93.5-99.5). Conclusion The two brachytherapy schedules reported in the present study showed similar results in clinical outcomes, however the 6 Gy at 1 fraction/week schedule had the best outcome in terms of late vaginal toxicity. Further larger studies are needed to confirm the present results.