A systematic review of the effects of screening for colorectal cancer using the faecal occult blood test, hemoccult.
OBJECTIVE
To review effectiveness of screening for colorectal cancer with faecal occult blood test, Hemoccult, and to consider benefits and harms of screening.


METHODS
Systematic review of trials of Hemoccult screening, with meta-analysis of results from the randomised controlled trials.


METHODS
Four randomised controlled trials and two non-randomised trials of about 330 000 and 113 000 people respectively aged >=40 years in five countries.


METHODS
Meta-analysis of effects of screening on mortality from colorectal cancer.


RESULTS
Quality of trial design was generally high, and screening resulted in a favourable shift in the stage distribution of colorectal cancers in the screening groups. Meta-analysis of mortality results from the four randomised controlled trials showed that those allocated to screening had a reduction in mortality from colorectal cancer of 16% (relative risk 0.84 (95% confidence interval 0.77 to 0.93)). When adjusted for attendance for screening, this reduction was 23% (relative risk 0.77 (0.57 to 0.89)) for people actually screened. If a biennial Hemoccult screening programme were offered to 10 000 people and about two thirds attended for at least one Hemoccult test, 8.5 (3.6 to 13.5) deaths from colorectal cancer would be prevented over a period of 10 years.


CONCLUSIONS
Although benefits of screening are likely to outweigh harms for populations at high risk of colorectal cancer, more information is needed about the harmful effects of screening, the community's responses to screening, and costs of screening for different healthcare systems before widespread screening can be recommended.
The Australasian Cochrane Centre, Flinders Medical Centre, Bedford Park, Adelaide 5042, Australia. bernie.towler@m130.aone.net.au
B
B
Towler
L
L
Irwig
P
P
Glasziou
J
J
Kewenter
D
D
Weller
C
C
Silagy
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000097:blood / Q000517:prevention & control*; D005500:Follow-Up Studies; D006801:Humans; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D009780:Occult Blood; D011379:Prognosis; D011786:Quality Control; D016032:Randomized Controlled Trials as Topic / Q000592:standards; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016019:Survival Analysis