Inclusion Criteria:  Adult patients operated for colon tumors who have data on age, sex, data on a previously diagnosed colon tumor, data on incidental appendectomy, and a PHD finding for a removed appendix. Adult patients who have been diagnosed with acute appendicitis and have data on age, sex, data on the diagnosis of acute appendicitis and accompanying PHD findings, newly performed appendectomies.  Exclusion Criteria:  We will exclude from the analysis patients who had previous appendectomy, appendectomy has not been performed or we do not have an accompanying PHD finding of the appendix, and patients younger than 18 years.