Follow-up of patients with colorectal cancer: numbers needed to test and treat J. Kievit* Departments of Surgery and of Medical Decision Making, Leiden University Medical Center, K6-26, PO Box 9600, 2300 RC Leiden, The Netherlands Received 18 December 2001; accepted 13 February 2002 Abstract Follow-up after curative treatment of patients with colorectal cancer has as its main aims the quality assessment of the treatment given, patient support, and improved outcome by the early detection and treatment of cancer recurrence. How often, and to what extent, the final aim, improved survival, is indeed realised is so far unclear. A literature search was performed to provide quanti- tative estimates for the main determinants of the effectiveness of the follow-up. Data were extracted from a total of 267 articles and databases, and were aggregated using modern meta-analytic methods. In order to provide one more colorectal cancer patient with long-term survival through follow-up, 360 positive follow-up tests and 11 operations for colorectal cancer recurrence are needed. In the remaining 359 tests and 10 operations, either no gains are achieved or harm is done. As the third aim of colorectal cancer follow-up, improved survival, is realised in only few patients, follow-up should focus less on diagnosis and treatment of recurrences. It should be of limited intensity and duration (3 years), and the search for preclinical cancer recurrence should primarily be per- formed by carcino-embryonic antigen (CEA) testing and ultrasound (US). The focus of colorectal cancer follow-up should shift from the early detection of recurrence towards quality assessment and patient support. As support that is as good or even better can be provided by a patient’s general practitioner (GP) or by specialised nursing personnel, there is no need for routine follow-up to be performed by the surgeon. # 2002 Elsevier Science Ltd. All rights reserved. Keywords: Colorectal cancer; Follow-up; Recurrence; Survival 1. Introduction Most patients, who have been operated upon for colorectal cancer, undergo some form of oncological follow-up, which means that they are followed on an outpatient basis for many years. Follow-up serves at least three main purposes: 1. Quality assessment: by checking on treatment outcomes, negative as well as positive, such as complications of treatment, cancer recurrences and disease-free survival 2. Support: by checking and providing help for the somatic, psychological, and/or social problems that patients may experience after having been diagnosed with and treated for cancer, and 3. Improved survival: by the preclinical detection of asymptomatic recurrence, with the hope of pro- viding better outcome than if recurrence had been detected later as a result of symptoms. Although the latter purpose, improved survival, has been investigated in different types of studies, it is still not clear to what extent it can really be achieved, and what follow-up should be implemented to best serve this purpose [1,2]. Earlier, we demonstrated that a survival benefit due to follow-up is dependent on the joint fulfil- ment of many conditions [3]. Thus there must be at least an asymptomatic recurrence leading to a positive test for follow-up to be effective. In addition, the patient must be free from extensive metastases and fit enough to undergo surgery. Surgery must be with curative intent, and the patient must survive a resection that is micro- scopically radical (R0). Finally, the patient should, after hospital discharge, not die early from other causes, nor should he/she develop a second manifestation of cancer- recurrence in the near future. 0959-8049/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved. PII: S0959-8049(02)00061-8 European Journal of Cancer 38 (2002) 986–999 www.ejconline.com * Tel.: +31-71-526-4574/526-3967. E-mail address: j.kievit@lumc.nl; URL: http://www.medfac.leidenuniv.nl/mdmu/kievit.htm(J.Kievit).