The incidence of right-sided colon cancer in patients aged over 40 years with acute appendicitis: A systematic review and meta-analysis.

OBJECTIVES: To determine the incidence of right-sided colon cancer in patients aged over 40 years with acute appendicitis. METHODS: We performed a systematic review in accordance with PRISMA statement standards. A search of electronic information sources was conducted to identify all studies reporting the incidence of right-sided colon cancer in patients aged over 40 years with acute appendicitis. The ROBINS-I tool was used to assess the risk of bias of the included studies. Fixed-effect and random-effects models were applied to calculate pooled outcome data. RESULTS: A total of 8 studies, enrolling 4328 patients, were included. The mean age of patients was 59 (95% CI 53-65); 54% were male (2330 out of 4328). The diagnosis of appendicitis and colon cancer were based on histological assessment only. In patients aged over 40 years the pooled incidence of right-sided colon cancer was 1.043% (95% CI 0.762-1.367); the level of between-study heterogeneity was low (I2 = 0%, P = 0.45). The risk of right-sided colon cancer in patients aged over 40 with acute appendicitis was significantly higher than the risk in general population [standardised risk ratio (SRR): 10.65 95% CI 3.83-29.66, P < 0.0001]. The number needed to treat (NNT) was calculated as 112 patients (95% CI 83-171). The quality of available evidence was moderate. CONCLUSIONS: The risk of right-sided colon cancer in patients aged over 40 years with acute appendicitis is 10 times higher than the risk in general population. This suggests a need for routine preoperative CT scans and postoperative colonic assessment in all patients aged over 40 years presenting with acute appendicitis.