Article
Etiologic Insights from Surface-Adjustment of Colorectal Cancer Incidences. An Analysis of the U.S. SEER Data 2000-2004.
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Published: | September 10, 2008 |
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Outline
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Background & Aims
The subsite-specific comparison of the incidence of cancer within the colorectum is complicated because the mucosa surface and therefore the amount of epithelial cells at risk varies considerably among the subsites. The aim of this study was to provide subsite-specific estimates of the colon mucosa surface and to provide mucosa-surface adjusted cancer incidence estimates of colon subsites that allow a more valid comparison of the subsite-specific incidences.
Methods
We extracted subsite-specific incidence rates of colorectal cancer from the Surveillance, Epidemiology, and End Results Program of the years 2000-2004 [Ref. 1]. Rates were age-standardized to the U.S. standard population in the year 2000. We estimated the mucosa surface of each segment of the colorectum using elementary geometry and calculated surface-adjusted incidence rates by dividing the observed age-standardized incidence rates by the estimated surface areas.
Results
After adjustment for surface area, the incidence relations among the colorectal subsites changed. Within the colon the highest surface-adjusted rates are observed in the cecum and vermiform appendix. Rates of the ascending, transverse, descending and sigmoid colon are considerably lower. The surfaced-adjusted incidence of rectal cancers is about 14-24-fold higher than the rate of cancers of the transverse colon.
Conclusions
Our analyses illustrate that the subsite-specific distribution of the incidence of cancers is markedly influenced by the adjustment of surface area of the colorectum. The surface adjustment shows that colorectal cancer is most common in the dependent parts of the large bowel (vermiform appendix, cecum, and rectum).
Acknowledgments
We thank Kenneth J. Rothman and Reinhard Pabst for their helpful comments.
References
- 1.
- Surveillance, Epidemiology, and End Results (SEER) Program (http://www.seer.cancer.gov/) SEER*Stat Database: Incidence - SEER 9 Regs Limited-Use, Nov 2006 Sub (1973-2004), National Cancer Institute, DCCPS, Surveillance Research Program, Cancer Statistics Branch, released April 2007, based on the November 2006 submission. [computer program]. 2006.