ESTRO 2021 Abstract Book

S250

ESTRO 2021

Planned radiotherapy dose per protocol was not delivered in 9 patients (15.3%) in the 50Gy group and in 15 patients (23.1%) in the 66Gy group (p= 0.27) but only 2 patients had doses above 50Gy. No significant differences in the causes of deaths were observed between the 2 groups (p= 0.78). 59 patients (54.1%) had died in the 50Gy group and 65 patients (60.2%) in the 66Gy group (p= 0.37) with a median follow up 35.3 months (range: 2.0-65.7) and 35.5 months (range: 1.3-60.7), respectively. Median overall survival was 25.2 months (95% CI 17.8-NR) in the 50Gy group and 23.5 months (95% CI 14.5-32.2) in the 66Gy group (HR 1.14, 95% CI 0.82-1.59; p= 0·44). Median overall survival was 19.7 months with 3D conformal (95% CI 12.4-27.3) and 25.5 months (95% CI 18.5-NR) with IMRT (p= 0.07). Conclusion Dose escalated chemoradiotherapy delivering 66Gy with concomitant elective nodal irradiation can be delivered without significant increase in late toxicity and no significant differences in the causes of death between the 2 dose levels. Overall survival is similar between the 2 treatment arms with a trend toward better survival with IMRT. OC-0337 Quality of life, functional outcome and late toxicity in patients treated within the RAPIDO trial E. Dijkstra 1 , G. Hospers 1 , C. van de Velde 2 , J. Fleer 3 , R. Bahadoer 2 , M. Guren 4 , J. Tjalma 5 , H. Putter 6 , E. Meershoek-Klein Kranenbarg 2 , A. Roodvoets 2 , A. ten Tije 7 , J. Capdevila 8 , M. Hendriks 9 , A. Cervantes 10 , P. Nilsson 11 , B. Glimelius 12 , B. van Etten 13 , C. Marijnen 14,15 1 University Medical Center Groningen, Medical Oncology, Groningen, The Netherlands; 2 Leiden University Medical Center, Surgery, Leiden, The Netherlands; 3 University Medical Center Groningen, Health Sciences, Groningen, The Netherlands; 4 Oslo University Hospital, Oncology, Oslo, Norway; 5 University Medical Center Groningen, Gastroenterology and Hepatology, Groningen, The Netherlands; 6 Leiden University Medical Center, Biomedical Datasciences, Leiden, The Netherlands; 7 Amphia Hospital, Medical Oncology, Breda, The Netherlands; 8 Vall Hebron University Hospital and Vall Hebron Institute of oncology, Medical Oncology, Barcelona, Spain; 9 Northwest Clinics, Medical Oncology, Alkmaar, The Netherlands; 10 Biomedical Research Institute Incliva, University of Valencia, Medical Oncology, Valencia, Spain; 11 Karolinska University Hospital, Surgery, Stockholm, Sweden; 12 Uppsala University, Immunology, genetics and pathology, Uppsala, Sweden; 13 University Medical Center Groningen, Surgery, Groningen, The Netherlands; 14 Netherlands Cancer Institute, Radiation Oncology, Amsterdam, The Netherlands; 15 Leiden University Medical Center, Radiation Oncology, Leiden, The Netherlands Purpose or Objective The RAPIDO trial randomized locally advanced rectal cancer (LARC) patients between pre-operative 5x5 Gy radiotherapy followed by chemotherapy (EXP) and long-course chemoradiotherapy with optional post- operative chemotherapy (STD). Previous results showed, in favour of the EXP group, a decrease in three-year disease related treatment failure (DrTF) from 30.4% to 23.7% and an increase in pCR rate from 14% to 28%. This study examines health related quality of life (HRQL), functional outcome and late toxicity in RAPIDO patients to balance benefits and risks. Materials and Methods Resected patients without DrTF at 36 months after surgery were included and received HRQL (EORTC QLQ- C30, QLQ-CR29, QLQ-CIPN20 and low anterior resection syndrome (LARS) questionnaires. All symptom and functional scales or items with clinically meaningful (mean difference of ≥ 5 points) and statistically significant (p<0.01) differences are reported. Patients without DrTF were included for toxicity assessment (CTCAEv4.0) at 6, 12, 24 and 36 months (all +/- 3 months) after surgery as assessed by the responsible physician. To determine the effects of post-operative chemotherapy, the STD group was split into STD+ and STD-. Results In total, 453 of 578 eligible patients returned the HRQL questionnaires (78.4%). No statistically significant differences in the answers to QLQ-C30 (figure 1), QLQ-CR29 and LARS questionnaire were observed between the two treatment groups or the three subgroups (EXP, STD- and STD+). Sensory-related symptoms from the CIPN-20 were more often reported in the EXP group when compared to all STD patients (p<0.001), but not when compared to the STD+ patients (except for pain in toes or feet; p=0.005). Neither toxicity of any grade, nor > grade 3 was significantly different between the EXP group and the STD group at any time-point. At 6 months, both the EXP and STD+ group experienced significantly more grade 1-2 toxicity compared to the STD- group. For the EXP group, this difference was still present at 12 months. However, no significant differences were observed between the EXP and STD+ group (figure 2). Neurological toxicity grade 1-2, but not grade ≥3, differed significantly between the three group at all-time points.