ESTRO 36 Abstract Book

S170 ESTRO 36 2017 _______________________________________________________________________________________________

time intervals. The 1 st group included 305 patients undergone TME within 6 weeks, the 2 nd group included 1610 patients undergone TME within 7-12 weeks, and the 3 rd group included 198 patients undergone TME within 13 or more weeks after CRT, respectively. Results Data on 2113 patients treated between 1997 and 2016 were retrieved from the historical database of gastrointestinal radiation oncologists joined into the study. Recruitment in the period investigated by the study took place as follows: 183 patients from 1997 to 2002, 550 from 2003 to 2008, and the majority, 1380, from 2009 to 2016. Five hundred and eighty two patients had stage II (T3–4, N0) and 1531 had stage III (any T, N1–2) histological proven invasive rectal adenocarcinoma. A CRT schedule with one (1600 pts) or 2-drugs was administered (513 pts). Overall, pCR were 468 (22%). Among the 2113 assessable patients the proportion of patients achieving a pCR increased according with time interval, as follows: 12.4% (1 st group), 22.9% (2 nd group), and 30.8% (3 rd group) (p<0.001, ANOVA test), respectively. The 1 st group had a pCR odds ratio of 0.47 compared to 2 nd group, while the latter had a pCR odds ratio of 0.66 compared to 3 rd group. Moreover, 1 st group had a pCR odds ratio of 0.31 compared to 3 rd group. The rate of complete response increments for each week of waiting was 1.5% (about 0.2%/die) . At univariate analysis, time interval (p<0.001), radiotherapy dose (>5040 cGy; p=0.013), and clinical tumor stage (p=0.029) were significantly correlated to pCR. The positive impact of time interval (p<0.001) and clinical tumor stage (p=0.038) were confirmed by multivariate analysis, in agreement with the literature data (Table 1).

Purpose or Objective As result of the aging population, increasing life expectancy and increasing rectal cancer incidence, more elderly patients will undergo treatment for rectal cancer. Neoadjuvant (chemo)radiotherapy and surgery are associated with considerable morbidity and mortality. In this study we compared treatment course, postoperative complications and quality of life (QoL) in older versus younger rectal cancer patients. Material and Methods All patients within the Dutch prospective colorectal cancer cohort with primary rectal cancer referred for Radiotherapy at the UMC Utrecht between February 2013 and January 2016 were selected. QoL was assessed with the EORTC-C30 questionnaire before start of neoadjuvant treatment and at 3, 6 and 12 months afterwards. Patients were divided into elderly (≥70 years) and non-elderly (<70 years). Differences in QoL were analyzed with generalized estimation equations, adjusted for baseline score, and stratified according to presence of postoperative complications. Results A total of 115 elderly (33.3%) and 230 non-elde rly (66.6%) patients were included. Compared to non-eld erly, elderly patients were less often male (62.6% vs. 75.2%), had more often previous abdominal surgery (40.9% vs. 30.0%) and presence of comorbidities (80.0% vs. 59.1%). Elderly were more likely to undergo short-course radiation with delayed surgery and less likely to undergo chemoradiation (resp. 19.1% and 39.1% vs. 6.1% and 62.6% in non-elderly, p<.001). Surgery was performed equally in both groups (83.5% in elderly vs. 87.8% in non-elderly, p=.318). The reasons for no surgical treatment, included disease progression and poor performance status in elderly, and disease progression or a wait-and-see policy in non- elderly. No differences were observed in postoperative complications between elderly and non-elderly (surgical- and non-surgical complication rate 36,5% vs. 34,7%, p=.780), neither when stratified for type of neoadjuvant therapy or surgical procedure. Trends of functional QoL domains were similar between elderly and non-elderly during the first year after diagnosis with lowest scores at 3 and/or 6 months. In elderly, postoperative complications had a stronger impact on physical- and role functioning (at 6 months resp. MD -19.2 and -18.4, relative to non-elderly with postoperative complications) (Figure 1). In a sensitivity analysis, comparing patients >80 years with younger patients, comparable results were observed.

Conclusion We confirmed on a population-level that lengthening the interval (>13 weeks) from CRT to surgery improves the pCR in comparison to historic data, possibly due to technical improvement of radiotherapy such as the ability of high- precision dose delivery and real-time knowledge of the target volume location. PV-0327 The effect of postoperative complications on Quality of Life in elderly rectal cancer patients A.M. Couwenberg 1 , F.S.A. De Beer 1 , M.P.W. Intven 1 , M.E. Hamaker 2 , W.M.U. Van Grevenstein 3 , H.M. Verkooijen 4 1 UMC Utrecht, Radiotherapy, Utrecht, The Netherlands 2 Diakonessenhuis, Geriatrics, Utrecht, The Netherlands 3 UMC Utrecht, Surgery, Utrecht, The Netherlands 4 UMC Utrecht, Imaging Division, Utrecht, The Netherlands

Conclusion Elderly are more often treated by less invasive treatments, which deviates from the standard treatment. Compared with younger patients, elderly have similar postoperative complication rates. Nevertheless, the impact of postoperative complications on physical- and role functioning is stronger in elderly than in younger patients. These results suggest a need to predict the frailest elderly patients who are at risk for postoperative morbidity and hereby an impaired quality of life.