Scope of the Problem
For the average-risk person, an initial screening colonoscopy is recommended beginning at age 50 for both men and women. In this population, it is estimated that the risk of developing a colorectal adenoma is approximately 19% and that 2-5% of sporadic polyps will develop into an invasive carcinoma (Labianca, 2005). The goal of screening is to remove adenomas prior to evolution to a carcinoma. The transition rates from advanced adenomas (AA) to colorectal cancer (CRC) are similar between men and women, although the prevalence of AA and CRC are higher in men than in women (Brenner, 2007).
Ferlitsch and colleagues (2011) conducted a study in conjunction with the Austrian national project entitled Quality Management for Colon Cancer Prevention whose aim was to identify control standards for quality and documentation of screening colonoscopies in Austria. Colonoscopy was identified as a screening method in Austria in 2005. The objective of their study was to identify the most appropriate age for initial screening for both men and women to achieve a higher detection rate of adenoma, AA and CRC potentially resulting in a decreased mortality rate for CRC.
Study Facts and Results
- Two hundred twenty-five endoscopic units who were participating in the Austrian Federation of the Statutory Insurance Institutions and the Austrian Cancer Aid, Certificate of Quality for Screening Colonoscopy project participated
- Data from 44,350 screening colonoscopies in Austria between 2007 and 2010 were reviewed; 22,598 women (51 %) and 21, 752 men (49%)
- Median ages were 60.7 years for men and 60.6 for women
- Adenomas were found in 19.7% of individuals screened, AAs in 6.3% and CRCs in 1.1%; number needed to screen (NNS) were 5.1, 15.9 and 90.9 respectively
- Male sex was significantly associated with higher prevalence of adenomas 24.9 % vs. 14.8%,
- p <.001; AAs 8.0% vs. 4.7%, p <.001; and CRCs 1.5% vs. 0.7%, p <.01
- The prevalence of AAs in 50- to 54-year-old individuals was 5.0% in men and 2.9% in women (adjusted p = .001); NNS in men was 20 vs. 34 in women
- There was no statistical significance between the prevalence and NNS of AAs in men aged 45 to 49 years compared with women aged 55-59 years
The authors concluded that the prevalence of NNS of AAs were comparable between men aged 45 to 49 and women aged 55 to 59 years. They commented that this study did identify significantly higher rates of adenomas, AAs and CRCs among men compared to women in all age groups and that it could serve as a basis for future research demonstrating the clinical effectiveness of colonoscopic screening at different ages.
The findings of this Austrian, population-specific study are intriguing. In the United States (US), screening for adults aged 50-75 years has increased from 52% in 2002 to 63% in 2008 (Richardson, 2010). The increase in screening may be responsible for the declining incidence of CRC which had accelerated from 1998 through 2007. CRC is preventable by removing pre-cancerous lesions or adenomatous polyps long before invasive cancer develops. While there is currently a 63% compliance rate for CRC screening in the US, it remains considerably less than complete uptake. This uptake is based on specific guidelines that are equally age- and sex-specific which allows for easy interpretation of guidelines. Before consideration for segregating guidelines between sexes and age groups, there clearly needs to be further prospective studies conducted both in and outside the United States to demonstrate the relative effect of screening at different ages among the sexes.
Brenner, H., Hoffmeister, M., Stegmaier, C., Brenner, G., Altenhofen, L., Haug, U. (2007). Risk of progression of advanced adenomas to colorectal cancer by age and sex: estimates based on 840,149 screening colonoscopies. Gut, 56, 1585-1589. doi:10.1136/gut.2007.122739 Link to free full text http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2095643/?tool=pubmed
Ferlitsch, M., Reinhart, K., Pramhas, S., Wiener, C., Gal, O., Bannert, C.,…Weiss, W. (2011). Sex-specific prevalence of adenomas advanced adenomas, and colorectal cancer in individuals undergoing screening colonoscopy. Journal of the American Medical Association, 306, 1352-1358. doi:10.1001/jama.2011.1362 Link to abstract:
Labianca, R., Beretta, G. D., Mosconi, S., Milesi, L., & Pessi, M. A. (2005). Colorectal cancer: screening. Annals of Oncology, 16 (Supplement 2): ii127-ii132. doi:10.1093/annonc/mdi730 Link to free full text http://annonc.oxfordjournals.org/content/16/suppl_2/ii127.full.pdf+html
Richardson, L.C., Rim, S.H., & Plescia, M. (2010). Vital signs: Colorectal cancer screening among adults aged 50-75 years - United States, 2008. Morbidity and Mortality Weekly Report (Centers for Disease Control and Prevention), 59: 808-812. Retrieved from http://www.cdc.gov/mmwr/