History of negative colorectal endoscopy and risk of rectosigmoid neoplasms at screening flexible sigmoidoscopy

Systematic review and meta-analysis of the evidence for flexible sigmoidoscopy as a screening method for the prevention of colorectal cancer

BACKGROUND

Colorectal cancer is a significant cause of death. Removal of precancerous adenomas, and early detection and treatment of cancer, has been shown to reduce the risk of death. The aim of this review and meta-analysis was to determine whether flexible sigmoidoscopy (FS) is an effective population screening method for reducing mortality from colorectal cancer.

METHODS

MEDLINE (1946 to December 2012) and Embase (1980-2012, week 15) were searched for randomized clinical trials in which FS was used to screen non-symptomatic adults from a general population, and FS was compared with either no screening or any other alternative screening methods. Meta-analysis was carried out using a random-effects Mantel-Haenzsel model.

RESULTS

Twenty-four papers met the inclusion criteria, reporting results from 14 trials. Uptake of FS was usually lower than that for stool-based tests, although FS was more effective at detecting advanced adenoma and carcinoma. FS reduced the incidence of colorectal cancer after screening, and long-term mortality from colorectal cancer, compared with no screening in a selected population. Compared with stool-based tests in a general population, FS was associated with fewer interval cancers.

CONCLUSION

FS is efficacious at reducing colorectal cancer mortality compared with no screening. It is more effective at detecting advanced adenoma and carcinoma than stool-based tests. FS may be compromised by poorer uptake. Introduction of FS as a screening method should be done on a pilot basis in populations in which it is not currently used, and close attention should be paid to maximizing uptake. The relative risk of adverse events with FS compared with stool-based tests should be quantified, and its real-world effectiveness evaluated against the most effective stool-based tests.

Changing epidemiology of colorectal cancer makes screening sigmoidoscopy less useful for identifying carriers of colorectal neoplasms

BACKGROUND

There is renewed interest in flexible sigmoidoscopy (FS) colorectal cancer (CRC) screening following trials showing significantly reduced CRC incidence and mortality.

AIMS

To evaluate the potential usefulness of FS screening in our population.

METHODS

We examined rectosigmoid (RS) cancer epidemiology in our Jewish population using Israel National Cancer Registry data, computed by CRC site, age groups, and gender. We also reviewed endoscopy-screening publications for prevalence of RS and proximal advanced adenomas (AAP) and having both or either.

RESULTS

During 1980-2008, there were 64,559 CRCs registered; 31.6 % were RS cancer which has now decreased to 29 % of men's and 26 % of women's CRC (both P < 0.01). In <50 year olds, RS cancer occurred in 42 % of males' and 35 % of females' CRC, and in the last 2 decades this ratio is unchanged. In 50-74 year olds, RS cancer decreased to stable levels of 32 % of males' and 29 % females' CRC (both P < 0.01). In ≥75 year olds, RS cancer progressively decreased to 24 % of males' and 22 % females' CRC (both P < 0.001). From endoscopy screening reports in 40-79 year olds, RS AAPs occurred in 2.0-5.8 %, being least in women, most in men, and not increased with aging. Some 50-57 % of screenees had both RS and proximal AAPs, least when aged 40-49 years at 25 %, women were 35 %, and with aging 40 %, but most in men at 70 %.

CONCLUSIONS

With the changing CRC epidemiology, having fewer RS neoplasms but more proximal cancer, the effectiveness of FS screening for identifying significant neoplasms decreases with screenees' age and especially in females. These make FS screening less suitable for our aging and increasingly female population.