Kai S. Lehmann, Carsten Klinger, Johannes Diers, Heinz-Johannes Buhr, Christoph-Thomas Germer, Armin Wiegering

• Background Up to 20 per cent of all operations for patients with colorectal cancer (CRC) are performed in octogenarians. Anastomotic leakage is a leading cause of morbidity and death after resection for CRC. The aim of this study was to assess the rate of anastomosis creation, the risk of anastomotic leakage and death in surgery for left-sided CRC in elderly patients. Methods This prospective cohort study compared patients less than 80 and 80 or more years with left-sided CRC resection performed between 2013 and 2019. Data were providedBackground Up to 20 per cent of all operations for patients with colorectal cancer (CRC) are performed in octogenarians. Anastomotic leakage is a leading cause of morbidity and death after resection for CRC. The aim of this study was to assess the rate of anastomosis creation, the risk of anastomotic leakage and death in surgery for left-sided CRC in elderly patients. Methods This prospective cohort study compared patients less than 80 and 80 or more years with left-sided CRC resection performed between 2013 and 2019. Data were provided from a risk-adjusted surgical quality-assessment system with 219 participating centres in Germany. Outcome measures were the rate of anastomoses, anastomotic leakages, death at 30 days and 2-year overall survival (OS). Propensity score matching was used to control for selection bias and compare subgroups of patients of less than 80 and 80 or more years. Results Out of 18 959 patients, some 3169 (16.7 per cent) were octogenarians. Octogenarians were less likely to receive anastomoses (82.0 versus 92.9 per cent, P < 0.001; odds ratio 0.50 (95 per cent c.i. 0.44 to 0.58), P < 0.001). The rate of anastomotic leakages did not differ between age groups (8.6 versus 9.7 per cent, P = 0.084), but 30-day mortality rate after leakage was significantly higher in octogenarians (15.8 versus 3.5 per cent, P < 0.001). Overall, anastomotic leakage was the strongest predictor for death (odds ratio 4.95 (95 per cent c.i. 3.66 to 6.66), P < 0.001). In the subgroup with no leakage, octogenarians had a lower 2-year OS rate than younger patients (71 versus 87 per cent, P < 0.001), and in the population with anastomotic leakage, the 2-year OS was 80 per cent in younger and 43 per cent in elderly patients (P < 0.001). After propensity score matching, older age remained predictive for not receiving an anastomosis (odds ratio 0.54 (95 per cent c.i. 0.46 to 0.63), P < 0.001) and for death (odds ratio 2.60 (95 per cent c.i. 1.78 to 3.84), P < 0.001), but not for the occurrence of leakages (odds ratio 0.94 (95 per cent c.i. 0.76 to 1.15), P = 0.524). Conclusion Anastomotic leakage is not more common in octogenarians, but an age of 80 years or older is an independent factor for not receiving an anastomosis in surgery for left-sided CRC. The mortality rate in the case of leakage in octogenarians was reported to exceed 15 per cent.…