Since 1982, all patients undergoing surgery for colorectal cancer at the Department of Surgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany, are scheduled for periodic follow-up at our interdisciplinary ambulatory tumor center or outside of our hospital according to the recommendations of the German Cancer Society. The recommendations include—over a period of at least 5 years—regular physical examination, blood analysis, determination of carcinoembryonic antigen level, abdomen ultrasonography/computed tomography, chest radiography, and colonoscopy. All patient data are prospectively entered in a database, including preoperative tumor staging, preoperative multimodal treatment, details of the surgical procedure, occurrence of complications, postoperative histopathology, application of adjuvant or palliative treatment, and follow-up (date of last visit, date and site of tumor recurrence, date of tumor-related or unrelated death, cause-specific and recurrence-free survival).15 (link) Information from patients followed outside of our institution is obtained by periodic phone calls to the responsible general practitioners or gastroenterologists.
For this analysis, consecutive complete data sets of patients with resection of colorectal AC, MAC, or SC were extracted. Patients with other histological subtypes and patients without oncological resection of their primary tumor were not included. The latest date of inclusion and follow-up was October 1, 2012. Histological, clinical, and survival data of patients with classical AC were compared with those of patients with MAC and SC. All patients were staged according to the seventh edition of the International Union Against Cancer (UICC)/American Joint Committee on Cancer (AJCC) tumor staging system.