Follow-up of patients with colorectal cancer: numbers needed to test and treat.

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 quantitative 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 performed 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.