Abstract Book

S203

ESTRO 37

OC-0396 Late, persistent, substantial and treatment related symptoms (LAPERS): a new metric for late effects K. Tanderup 1 , R. Pötter 2 , R. Nout 3 , J. Lindegaard 4 , N. Jensen 4 , L. Fokdal 4 , A. Vittrup 4 , C. Kirisits 2 , S. Bentzen 5 , K. Kirchheiner 2 1 Aarhus University Hospital, Department of Oncology, Aarhus C, Denmark 2 Medical University of Vienna, Department of Radiation Oncology, Vienna, Austria 3 Leiden University Medical Center, Department of Radiation Oncology, Leiden, The Netherlands 4 Aarhus University Hospital, Department of Oncology, Aarhus, Denmark 5 University of Maryland School of Medicine, Department of Epidemiology and Public Health, Baltimore, USA Purpose or Objective In longitudinal analysis of late side effects after radiotherapy, different statistical methods can be applied to summarize the outcome. Crude incidence rates, actuarial estimates and prevalence rates are well known approaches. These methods characterize specific aspects of the time-evolution of morbidity. None of these metrics capture the duration of a given symptom at the level of an individual patient. A novel approach based on a stepwise selection of patients with late, persistent, substantial and treatment-related symptoms (LAPERS) is introduced to identify patients with substantial and persisting symptoms, which are likely treatment-related. Material and Methods Patient-reported symptoms (EORTC-QLQ) were analyzed for patients enrolled in the prospective, observational, and longitudinal study on MRI image-guided, adaptive brachytherapy in locally advanced cervical cancer (EMBRACE study). Patients with at least 3 late follow up assessments (6 months and ongoing) and information at baseline and early morbidity were selected for analysis. A LAPERS event for an individual patient was defined if the median grading over late follow up observations of a given symptom was at least “Quite a bit” or “Very much” (substantial symptoms). Baseline morbidity was taken into account by requiring the median to be worse than the minimum of baseline or early assessment scoring. The LAPERS approach was applied in four relevant patient- reported symptoms on urinary and bowel function. Results Within the EMBRACE cohort, 581 out of 1416 patients (41%) fulfilled the selection criteria for this analysis. Median follow-up was 36 months (IQR 24-54). Table 1 presents the outcome, based on the different methods of reporting. The crude incidence is nearly twice as high as the highest prevalence rate. The actuarial probabilities for substantial symptoms, based on the estimation for remaining patients at risk, are around 4-5% higher than crude incidence. The proportion of patients with LAPERS events is 4-5 times lower than crude incidence, indicating that in some cases symptoms are persistent. Conclusion Many symptoms after radiotherapy are fluctuating, transient or successfully treated. Incidence methods capture the (first) occurrence of an event and cannot discriminate whether patients suffer from chronic or transient treatment-related morbidity. The novel LAPERS metric for analyzing longitudinal symptoms aims to identify patients with late, persistent, substantial and treatment-related symptoms. Expectedly, the proportion of LAPERS events is substantially lower than the well- established crude incidence, prevalence rates and actuarial estimates in cervix cancer patients after radiochemotherapy. The LAPERS estimates will be further tested and validated within the EMBRACE study and beyond, as it seems to be sensitive in terms of quantifying the proportion of patients with persistent, clinically relevant symptom burden.

Proffered Papers: BT 4 - Brachytherapy rectum and breast

OC-0397 Single Institute Experience of HDR Intraluminal brachytherapy for rectal cancers with chemoradiation M. Rafi 1 , B. Intakhab 1 , S. Ahmed 1 , S. Rashid ul Ameen 1 , A. Maqbool 1 , A. Shehzad 1 , G. Sultan 1 , R. Mohsin 1 , A. Hashmi 1 , S. Adeeb ul hasan rizvi 1 1 Sindh Institute of urology and Transplantation SIUT, Radiation Oncology, Karachi, Pakistan Purpose or Objective Objective: To determine the feasibility and safety of high dose rate intraluminal brachytherapy (HDR-ILBT) boost during preoperative chemo-radiation for rectal cancer. Material and Methods Patients referred to our department between 2008 and 2013 were selected when they met the eligibility criteria. total of 150 patients were included in this study. patients with locally advanced rectal cancer (≥ T3 or N+), were treated initially with concurrent capecitabine (825 mg/m2 oral twice daily) and pelvic external beam radiotherapy (EBRT) (45 Gy in 25 fractions), then were randomized to group A; HDR ILBT group (n = 75) to receive 5.5-7 Gy × 2 to gross tumor volume (GTV) and group B; EBRT group (n = 75) to receive 5.4 Gy × 3 fractions to GTV with EBRT. All patients underwent total mesorectal excision Results Grade 3 acute toxicities were registered in 53 patients in group A and 32 in group B. Complete pathologic response of T stage (ypT0) in group A was registered in 44 patients and in group B, 12 patients had ypT0 (P < 0.001). Sphincter preservation was reported in 26/40 patients in group A and in 20/40 patients in group B (P < 0.01). Overall radiological response was 68.75% and 66.24% in Group A and B, respectively. During a median follow up of 36 months, late grade 1 and 2 sequelae were registered in 13 patients and 16 patients in the groups A and B, respectively. HDR-ILBT was found to be effective dose escalation technique in preoperative chemo radiation for rectal cancers, with higher response rates, down staging and with manageable acute toxicities. Conclusion High dose rate intraluminal brachytherapy was found to be more convenient, had satisfactory response rates and can be safely used as a tool to boost the gross tumor volume during preoperative chemoradiation. OC-0398 HDR brachytherapy boost for ductal carcinoma in situ of the breast with close or positive margins F. Gines 1 , M. Santos 1 , J.L. Guinot 1 , A. Moreno 1 , J. Fernandez 1 , M. Peña 1 , C. Boso 2 , M. Tortajada 1 , L. Arribas 1 1 Fundación Instituto Valenciano de Oncologia, Department of Radiation Oncology, Valencia, Spain