How much does colonoscopy reduce colon cancer mortality?

Variations between endoscopists in rates of detection of colorectal neoplasia and their impact on a regional screening program based on colonoscopy after fecal occult blood testing

BACKGROUND

There are few data about the performance variability among endoscopists participating to nationwide or regionwide colorectal cancer screening programs.

OBJECTIVE

To assess the variability of neoplasia detection rates among endoscopists participating in a regional colorectal cancer screening program based on colonoscopy after biennial fecal occult blood testing (FOBT).

DESIGN

Two rounds of colonoscopy were performed: round 1 took place in 2003 and 2004, and round 2 took place in 2005 and 2006. Secondary analysis of colonoscopy findings from the first 2 rounds was performed by using data drawn from all endoscopists who performed more than 30 colonoscopies in each round. Detection rates were adjusted for patient age and sex, and logistic regression analyses were conducted including these 2 variables and round number (1 or 2).

SETTING

District of Ille-et-Vilaine in Brittany (population >900,000) between 2003 and 2007.

MAIN OUTCOME MEASUREMENTS

The per-endoscopist adjusted rates of colonoscopies with at least 1, 2, or 3 adenomas, 1 adenoma 10 mm or larger, or a cancer.

RESULTS

Among the 18 endoscopists who performed 3462 colonoscopies, the adjusted detection rates were in the following ranges: at least 1 adenoma, 25.4% to 46.8%; 2 adenomas, 5.1% to 21.7%; 3 adenomas, 2.7% to 12.4%; 1 adenoma 10 mm or larger, 14.2% to 28.0%; and cancer, 6.3% to 16.4%. Multivariate analyses showed that the endoscopist was not an independent predictor of cancer detection, but was an independent predictor of detecting adenomas, regardless of category; the R(2) of the models ranged from 6% to 13% only.

LIMITATIONS

Other factors known to influence colorectal neoplasia occurrence and withdrawal time could not be taken into account.

CONCLUSIONS

In a screening program with a high compliance rate with colonoscopy after FOBT, interendoscopist variability had no effect on cancer detection, but did influence identification of adenomas. The clinical impact of such findings merits further evaluation.

Duration of symptoms, stage at diagnosis and relative survival in colon and rectal cancer

In colorectal cancer, the relation between duration of symptoms and stage at presentation and prognosis is not yet settled. All 1263 patients treated for colorectal cancer at Levanger Hospital, 1980-2004, and 2892 patients treated in Norway during 2004 were included. The association between symptom duration as an explanatory variable and tumour stage as a dependent variable was analysed using a proportional odds logistic regression model. Known duration of symptoms was divided into four categories: <1 week, 1-8 weeks, 2-6 months and >6 months. There was an inverse relationship between symptom duration and colon cancer TNM-stage, OR=0.73 (95% CI 0.63-0.84), p<0.001 (Levanger Hospital) and 0.84 (0.75-0.95), p=0.004 (Norway 2004), where the OR is per category of symptom duration. Duration of symptoms were also inversely associated with T-stage, N-stage and M-stage in colon cancer. These relationships were not found for rectal cancer. In colon cancer the relative five-year survival for the four intervals of symptom duration was 44%, 39%, 54% and 66%, p<0.001, in Levanger, 1980-2004, and four-year survival was 46%, 62%, 75% and 74%, p<0.001, in Norway 2004, respectively. For rectal cancer survival was not dependent on symptom duration. In a multivariate analysis of relative survival of patients with colon cancer, duration of symptoms was associated with survival independent of tumour differentiation and TNM-stage. Increasing duration of symptoms was positively associated with less advanced disease and better survival in colon cancer, but not in rectal cancer.