ESTRO 38 Abstract book

S817 ESTRO 38

EQD2 ≥85Gy improves CR, OS and DFS in patients with cervical cancer treated with dCRT independent of other risk factors. EP-1509 “Young adult” and “geriatric” locally advanced cervix cancer in Alberta: same but different? S. Menon 1 , S. Ghosh 2,3 , N. Vawda 3,4 , G. Menon 2,3 , M. Roumeliotis 1,5 , C. Doll 1,5 , E. Wiebe 3,4 , F. Huang 3,4 1 University of Calgary, Oncology, Calgary, Canada ; 2 Cross Cancer Institute, Oncology, Edmonton, Canada ; 3 University of Alberta, Oncology, Edmonton, Canada ; 4 Cross Cancer Institute, Radiation Oncology, Edmonton, Canada ; 5 Tom Baker Cancer Centre, Oncology, Calgary, Canada Purpose or Objective To review cervix cancer (CC) outcomes after radical (chemo(CH))radiotherapy (RT) including brachytherapy (BT), among women considered, in oncologic terms, younger and older. Material and Methods Of all CC patients seen in the province of AB (Canada), 01/2013–12/2015, for radical RT, including BT, we identified those aged <40 (young adult, YA) and >65 (geriatric, GA) at diagnosis. We excluded BT-alone cases. Health records were reviewed, abstracting demographic, clinicopathologic, patient-reported, treatment and outcomes data. Statistical analyses, descriptive and actuarial, were undertaken. Results N=30 YA women (median age 35.7 [23.6–39.1]) and n=26 GA (median age 71.1 [65.2–82.8]), 96% ECOG 0-1, were included. 40% of YA and 69% of GA were within 50 km of their treatment centre. Of the 9 coming from > 350 km away, 8 were YA. Four (all YA) did not live in AB. Age- adjusted Charlson Co-morbidity Index was 0 in all but n=3 YA (score ≤2); median was 3 [1–5] for GA. Most YA (73.3%) and GA (80.8%) had squamous histology, but adenocarcinoma was more common among YA (26.7%, vs. 11.5% for GA, p=0.15; a difference more pronounced between those aged <35 vs. ≥70). Older women had more advanced clinical tumor stage: (YA/GA) 46.7/30.8% IB, 13.3/19.2% IIA, 33.3/19.2% IIB, 0/11.5% IIIA, 6.6/11.5% IIIB, 0/7.7% IVA. YA and GA had similar (60% and 57.7%, respectively) pelvic and/or para-aortic (PA) nodal extent. Clinical/radiological distant metastasis was rare (2 YA, 1 GA). More YA had PET scan workup (76.7%, vs. 57.7%, p=0.13); more GA, EUA (61.5%, vs. 40.0%, p=0.11); MRI rates were similar. 93.3% YA (80.8% GA) received CHRT (pelvic±PA external beam (EB)RT with weekly cisplatin, and intracavitary±interstitial BT). 2 YA also had neoadjuvant CH. N=5 (all >70 years) had no CH; for those >70 who did, median 4 cycles [2–5]. Few had <3 cycles (3 YA, 2 GA). EBRT (40-50 Gy in 22-25 fractions, extra phase pre/post in 21.4%) preceded HDR-BT (3 fractions; less in n=4) or 1-fraction PDR-BT. BT complications were rare: all GA (3 procedural, 1 stroke). Overall treatment time (CHRT+BT) was 45.5 days median [41.0–84.0] in YA, GA not significantly different (51 [38–112]). Median HR-CTV D90 (Gy EQD2 10 ) was 90.2 [53.4–107.1] for YA, 86.0 [54.6– 105.5] for GA, p=0.30. Salvage surgery (1 YA, 2 GA) or RT (1 GA) were rare; palliative RT (4 YA, 4 GA) or CH (4 YA, 1 GA) more common. Patient reported outcomes (Table 1) evolved, pre-RT vs. at 6 months post-treatment. For a median 26 months [3–54] follow-up, 2-year overall (OS) for YA was 79.5% and for GA, 57.3% (p=0.473). Two-year cause-specific survival (CSS) was 74.5% for YA and 59.6% for GA (p=0.631) in this small cohort.

Conclusion CC seems more advanced in older women, who received less intense treatment in our provincial cohort. Patterns of care in primary RT for CC in AB differ in few but important ways among “oncologically” younger and older populations. How cancer outcomes might be improved by addressing the unique needs of each is not known. EP-1510 Phase I Trial of Stereotactic MR-guided Online Adaptive Radiotherapy for Ovarian Oligometastases L. Henke 1 , O. Green 1 , A. Curcuru 1 , S. Mutic 1 , S. Markovina 1 , J. Schwarz 1 , P. Grigsby 1 , C. Robinson 1 , A. Chundury 1 1 Washington University/Barnes Jewish Hospital, Radiation Oncology, Saint Louis- MO, USA Purpose or Objective Delivery of ablative radiation dose using SBRT within the central thorax, abdomen, and pelvis risks toxicity due to target proximity to organs-at-risk (OARs). Stereotactic MR- guided online adaptive radiotherapy (SMART) has been previously shown to improve the therapeutic index of SBRT for abdominal cancers. The feasibility and safety of this approach to treat ovarian oligometastases has not been evaluated. We report the results of a Phase I prospective trial investigating the feasibility and safety of SMART for patients with oligometastatic ovarian cancer. Material and Methods 10 patients with oligometastatic ovarian cancer were enrolled in a phase I trial (NCT02582931) between 9/2016 to 5/2018. All included patients had prior abdominopelvic resection and had received prior chemotherapy, including intraperitoneal chemotherapy in 5/10. Patients were treated with SMART using a 0.35T integrated MR-IGRT unit. 17 lesions were treated, at sites including the central thorax (3), the abdomen (5), and pelvis (9). The prescription was 35 Gy/5 fractions (goal of 95% PTV coverage), with optional dose escalation (DE) up to 50Gy/5 fractions, subject to strict maximum point dose (0.5cc) OAR constraints. During each fraction, physicians re-segmented a daily volumetric setup MRI. Initial plans were applied to daily anatomy to evaluate for OAR constraint violation, or if dose escalation (DE) > 7 Gy/fraction was possible. If either criterion existed, online re-optimization, QA, and delivery of a new plan were performed while the patient remained on-table. Feasibility of SMART was defined as delivery of >80% of planned fractions. Local control was evaluated by RECIST and acute toxicity (within 6 months of treatment) was evaluated by CTCAE v4.3 criteria. Results 100% of SMART fractions were delivered, with a median on-table time of 63 minutes. Each patient received at least 1 adapted fraction and 38/65 (58%) of fractions were adapted, primarily for abdominal and pelvic sites (37/38).