ESTRO 36 Abstract Book

S372 ESTRO 36 _______________________________________________________________________________________________

treatment MRI was checked in all patients 3 months after CCRT completion. Out of the 545 patients, 53 with residual cervical cancer based on MRI following definitive CCRT were included in this analysis. Results Thirty-two patients were disease-free at the last follow- up. Of them, 31 had a residual tumor size of ≤ 2 cm. Of these 32 women, 30 showed spontaneous regression of residual tumor during follow-up without salvage treatments, whereas the remaining two were alive with no evidence of disease after salvage surgery and chemotherapy. Disease progression was observed in 21 patients, including 7 local, 8 distant and 6 local and distant failures. Of these 21 women, 13 died of disease, 6 were alive with disease, and 2 remained disease-free after salvage treatments. Initial and residual tumor sizes were significant prognostic factors for overall survival; only residual tumor size was significant for local progression- free survival. Conclusion About 60% of patients with residual disease detected on post-treatment MRI remained disease-free without further disease progression. Careful observation without immediate salvage treatments might be feasible in selected patients with a residual tumor size ≤ 2 cm. PO-0710 Concurrent chemoradiotherapy in locally advanced cancer cervix: Systematic review and meta- analysis N.R. Datta 1 , E. Stutz 1 , M. Liu 1 , S. Rogers 1 , A. Siebenhüner 2 , D. Klingbiel 3 , S. Singh 4 , S. Bodis 1 1 Kantonsspital Aarau, Radio-Onkologie, Aarau, Switzerland 2 University Hospital Zurich, Oncology, Zurich, Switzerland 3 Swiss Group of Clinical Cancer Research SAKK Coordinating Centre, Biostatistics, Bern, Switzerland 4 Sanjay Gandhi Postgraduate Institute of Medical Sciences, Radiotherapy, Lucknow, India Purpose or Objective Concurrent chemoradiotherapy (CTRT) is one of the preferred management strategies in cancer cervix. However, unlike early stage cancer cervix, the efficacy of CTRT in locally advanced cancer cervix (LACC) (stages IIB- IVA) has been contentious as the therapeutic benefit has not been consistently shown in various randomized clinical trials. A systematic review and meta-analysis was therefore conducted exclusively in LACC to explore the therapeutic efficacy of concurrent CTRT vs. radiotherapy (RT) for the endpoints - complete response (CR), long- term loco-regional control (LRC), overall survival (OS), grade III/IV acute and late toxicities. Material and Methods Six databases - Cochrane Library, PubMed, EMBASE, SCOPUS, Google Scholar and Web of Science were searched as per the PRISMA guidelines using MeSH words, 'Uterine cervical neoplasms” AND 'Radiotherapy” AND 'Drug Therapy”. This was supplemented by hand-searching and last updated on 29.8.16. The selection criteria included (a) patients exclusively/predominantly in LACC (b) no surgical intervention (c) randomized trials with CTRT vs. RT and (d) full length publications in English. Odds ratio (OR), risk ratio (RR) and risk difference (RD) for each of the above endpoints were estimated along with their test for heterogeneity (I 2 ). Subgroup analysis (Q values) and meta-regression (using CT regimes as covariates) were performed for each endpoint to explore the differences in outcomes with different CTRT approaches. Results 14 articles from a pool of 1788 citations were considered for the final analysis. A total of 2445 patients (CTRT: n=1217; RT: n=1228) were included in these trials. 96.6%

of these patients were LACC. A mean teletherapy dose of 48.2Gy (SD:±2.9) was delivered along with brachytherapy. The brachytherapy doses were variable and depended on the high, medium or low dose-rates of the units as available in each institution. Eight studies used CDDP alone, 4 had multiple agents CT with CDDP (5FU/Taxanes/BLM/VCR) and 2 were based on MMC. The OR, RR and RD for each endpoint is summarized in the Table. CTRT improved the CR (+10.2%, p=0.027, I 2 =8.72), LRC (+8.4%, p<0.001, I 2 =0.0) and OS (+7.5%, p<0.001, I 2 =0.0, Fig.) over RT alone. However, a 10.4% higher incidence of acute toxicities (p<0.001, I 2 =77.8) was evident with CTRT. Late toxicities in both groups were equivocal. Subgroup analysis and meta-regression for each of the 5 endpoints did not reveal any significant difference in outcomes with the 3 different CTRT regimes.

Conclusion In LACC, although CTRT offers a significant benefit over RT alone, it also results in significantly higher grade III/IV acute toxicities. As no specific CT regime was found to be specifically advantageous, the choice of CT agents could be presently based on cost considerations both for primary treatment and management of acute toxicities. This assumes importance especially in most resource constrained developing countries with limited infrastructure and resources but faced with the highest burden of LACC. PO-0711 Risk factors for insufficiency fractures in cervix cancer following intensity modulated radiotherapy A. Ramlov 1 , E. Pedersen 2 , L. Røhl 2 , E. Worm 3 , L. Fokdal 1 , J. Lindegaard 1 , K. Tanderup 4 1 Aarhus University Hospital, Department of Oncology, Aarhus C, Denmark 2 Aarhus University Hospital, Department of Radiology, Aarhus C, Denmark 3 Aarhus University Hospital, Department of Medical Physics, Aarhus C, Denmark 4 Aarhus University Hospital, Department of Oncology and Department of Medical Physics, Aarhus C, Denmark Purpose or Objective To investigate incidence and risk factors of pelvic insufficiency fracture (PIF) after definitive chemo- radiotherapy for locally advanced cervical cancer (LACC). Material and Methods 101 patients with LACC treated from 2008-2014 were analysed. Patients received weekly Cisplatin, external beam radiotherapy with 45Gy/25fx (node-negative