Introduction - The objective of this study was to estimate, in addition to the overall and specific prevalence of colorectal cancer (CRC), the prevalence of patients requiring follow-up or treatment for recurrence. Methods - Data from the Burgundy Registry of Digestive Cancers (1976–2005) on the incidence, survival, and recurrence of CRC were used. Statistical cure was defined as the point at which the excess risk of CRC-related death disappeared. Prevalence rates by age group, applied to the French population, were used to estimate the national number of prevalent cases. Results - The overall prevalence rates were 244.9 per 100,000 for men and 152.6 per 100,000 for women. The estimated number of people with CRC alive as of December 31, 2005, was 262,244 cases for all of France. Over the past 30 years, the 5-year partial prevalence has increased by 8.0% [6.7–9.4] per 5-year period. The incidence increased by 1.2% [0.3–2.2] and relative survival rates by 15% per 5-year period. Among all excess deaths due to CRC, 15.3% occurred between 5 years of follow-up and the statistical cure time, estimated at 9.3 years [8.3–10.4]. These results allow us to estimate that 188,314 patients required follow-up nationwide in 2005. Among them, 5.4% were being treated for recurrence. Conclusion - Improved survival largely explains the increase in the 5-year partial prevalence of colorectal cancers. These results suggest that clinical follow-up is necessary within 10 years of diagnosis. The prevalence of patients requiring follow-up or treatment for progressive recurrence is of great interest for assessing the burden of colorectal cancer. (R.A.)