BACKGROUND: Compared with the general population, patients with a previous colorectal cancer are at higher risk for a second colorectal cancer, but detailed risk analysis by subsite is scarce.
OBJECTIVE: Our goal was to investigate the risk of a second cancer in relation to subsite as a basis for planning surveillance strategies,.
DESIGN, SETTING, AND PATIENTS: This was a retrospective analysis of a prospectively designed, population-based cancer registry (The Netherlands Cancer Registry). Patients with a stage I, II, or III colorectal cancer diagnosed between 1989 and 2008 were included.
MAIN OUTCOME MEASURES: Cumulative incidence, standardized incidence ratio, and absolute excess risk for second primary cancers in subsites of the colon and rectum were estimated for follow-up periods of 2 to 5, 6 to 10, and more than 10 years after the index cancer in patients older than 50 years and in those aged 50 years or younger.
RESULTS: A total of 123,347 patients had a first invasive colorectal cancer diagnosed between 1989 and 2008. Of these, 1849 patients (1.5%) had a second colorectal lesion that was found more than 1 year after the initial cancer and diagnosed as a second primary colorectal cancer. In patients older than 50 years, the 20-year cumulative incidence for second cancers was 3.4% in the proximal colon, 1.2% in the distal colon, and 1.2% in the rectum. More than 60% of second cancers occurred within 5 years after the index cancer. The standardized incidence ratio was highest in the proximal-colon (1.9; 95% CI, 1.8–2.0), followed by the distal-colon (1.0, 95% CI, 0.9–1.1), and the rectum (0.9, 95% CI, 0.8–1.0). The corresponding absolute excess risks per 10 000 person years were 9 in the proximal colon, 0.1 in the distal colon, and 1 in the rectum. After 5 years of follow-up, elevated risk was observed only in the proximal colon. A similar risk pattern was observed in patients younger than 50 years. The absolute excess risk for a second cancer in the proximal colon increased over time. The proportion of stage III and stage IV second cancers increased from 31% during the first 5 years of follow-up to 38% after 10 years of follow-up.
LIMITATIONS: Limitations of this study included lack of data regarding polypectomy rates and interval of surveillance colonoscopies.
CONCLUSIONS: Compared with the general population, individuals with previous colorectal cancer have a higher risk for a second cancer in all subsites of the colon and rectum. Among long-term survivors older than 50 years, risk remains elevated only in the proximal colon. Further studies should be encouraged to develop a suitable surveillance method for aging, high-risk, long-term colorectal cancer survivors.
1 Department of Public Health, ErasmusMC, University Medical Center, Rotterdam, The Netherlands
2 Comprehensive Cancer Centre South (IKZ), Eindhoven, The Netherlands
3 Department of Surgery, Catharina Hospital Eindhoven, Eindhoven, The Netherlands
4 Department of Gastroenterology, Netherlands Cancer Institute, Amsterdam, The Netherlands
5 Department of Surgery, St. Elisabeth Hospital, Tilburg, The Netherlands
6 Tilburg School of Social and Behavioral Sciences, University of Tilburg, Tilburg, The Netherlands
Funding/Support: This work was supported by Dutch Cancer Society (KWF): The increasing burden of second primary cancers in the Netherlands: trend in incidence, survival and causes-of-death since 1970 (EMCR 2008–4132).
Financial Disclosure: None reported.
Correspondence: Valery Lemmens, Ph.D., ErasmusMC University Medical Center, Department of Public Health, Room AE-233, Postbox 2040, 3000 CA Rotterdam, The Netherlands. E-mail: firstname.lastname@example.org