Gastroenterology

Gastroenterology

Volume 146, Issue 3, March 2014, Pages 709-717
Gastroenterology

Original Research
Full Report: Clinical—Alimentary Tract
Reduced Risk of Colorectal Cancer Up to 10 Years After Screening, Surveillance, or Diagnostic Colonoscopy

https://doi.org/10.1053/j.gastro.2013.09.001Get rights and content

Background & Aims

Data from randomized controlled trials on the effects of screening colonoscopies on colorectal cancer (CRC) incidence and mortality are not available. Observational studies have suggested that colonoscopies strongly reduce the risk of CRC, but there is little specific evidence on the effects of screening colonoscopies.

Methods

We performed a population-based case-control study of 3148 patients with a first diagnosis of CRC (cases) and 3274 subjects without CRC (controls) from the Rhine-Neckar region of Germany from 2003 to 2010. Detailed information on previous colonoscopy and potential confounding factors was collected by standardized personal interviews. Self-reported information on colonoscopies and their indications was validated by medical records. We used multiple logistic regression to assess the association between colonoscopy conducted for specific indications within the past 10 years and risk of CRC.

Results

A history of colonoscopy was associated with a reduced subsequent risk of CRC, independently of the indication for the examination. However, somewhat stronger associations were found for examinations with screening indications (adjusted odds ratio [OR] 0.09, 95% confidence interval [CI] 0.07–0.13) than for examinations with diagnostic indications, such as positive fecal occult blood test result (OR, 0.33; 95% CI, 0.19–0.57), surveillance after a preceding colonoscopy (OR, 0.33; 95% CI, 0.24–0.45), rectal bleeding (OR, 0.28; 95% CI, 0.20–0.40), abdominal symptoms (OR, 0.15; 95% CI, 0.10–0.21), or other (OR, 0.21; 95% CI, 0.14–0.30). Colonoscopy was also associated with a reduced risk of cancer in the right colon, regardless of the indication, although to a smaller extent than for other areas of the colon (OR for screening colonoscopy, 0.22; 95% CI, 0.14–0.33).

Conclusions

In a population-based case-control study, the risk of CRC was strongly reduced up to 10 years after colonoscopy for any indication. Risk was particularly low after screening colonoscopy, even for cancer in the right colon.

Section snippets

Study Design and Study Population

Our analysis is based on data from the DACHS (Darmkrebs: Chancen der Verhütung durch Screening) study, a population-based case-control study conducted in the Rhine-Neckar area of Germany since 2003. In Germany, guaiac-based FOBT (samples from 3 consecutive days) and colonoscopy have been offered for primary screening in an opportunistic manner for a number of years. Between 1977 and 2002, annual screening by FOBT was offered for people aged 45 years or older. Since October 2002, annual

Results

The main characteristics of the cases and controls are shown in Table 1. Fifty-nine percent of the cases and controls were men, and the median age was 70 years in both groups. A family history of CRC and smoking were more common among cases than among controls, whereas controls more often had a higher level of education and had ever used aspirin, NSAIDs, or HRT regularly. The majority of cases were diagnosed in stage II or III, but all 4 stages were represented with several hundreds of cases.

Discussion

In this large population-based study, the risk of CRC was small up to 10 years after screening colonoscopy. Compared with people who never underwent colonoscopy, the risk of CRC was reduced by approximately 90% after controlling for confounding factors, and the risk was still reduced by almost 80% even for cancer in the right colon. A somewhat lower but still substantial risk reduction (by 67%–85% for total CRC and by 29%–78% for cancer in the right colon) was observed for those who underwent

Acknowledgments

The authors thank the study participants and the interviewers who collected the data, the hospitals and cooperating institutions that recruited patients for this study (Chirurgische Universitätsklinik Heidelberg, Klinik am Gesundbrunnen Heilbronn, Sankt Vincentiuskrankenhaus Speyer, Sankt Josefskrankenhaus Heidelberg, Chirurgische Universitätsklinik Mannheim, Diakonissenkrankenhaus Speyer, Krankenhaus Salem Heidelberg, Kreiskrankenhaus Schwetzingen, Sankt Marien und Sankt Annastiftkrankenhaus

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    Conflicts of interest The authors disclose no conflicts.

    Funding Supported by grants from the German Research Council (Deutsche Forschungsgemeinschaft, grants BR 1704/6-1, BR 1704/6-3, BR 1704/6-4, and CH 117/1-1) and the German Federal Ministry of Education and Research (grants 01KH0404 and 01ER0814). The sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript.

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