Progression rates of colorectal cancer by Dukes' stage in a high-risk group: analysis of selective colorectal cancer screening.
OBJECTIVE
The progression rates of colorectal cancer by Dukes' stage in a high-risk group were estimated and applied to evaluate the efficacy of different screening regimens.


METHODS
Of 6303 high-risk subjects invited to a colorectal cancer screening project with colonoscopy, 39 screen-detected cases and 16 postscreening cases were diagnosed with information available on Dukes' stage. A five-state Markov process was applied to estimate parameters pertaining to the disease natural history of colorectal cancer by Dukes' stage.


RESULTS
The estimates of the mean sojourn time in years were 3.10 for preclinical Dukes' A and B and 1.92 for preclinical Dukes' stages C and D. The predicted reductions of Dukes' stages C and D achieved by annual, biennial, 3-yearly, and 6-yearly screening regimens against the control group were 60%, 49%, 40%, and 25%, respectively. These, in turn, yield the corresponding predicted mortality reductions of 39%, 33%, 28%, and 18%.


CONCLUSIONS
These findings suggest that to achieve a 30% mortality reduction, as observed in annual fecal occult blood testing, a prudent interscreening interval with colonoscopy for this high-risk group should not be longer than 3 years.
Department of Internal Medicine, College of Public Health, National Taiwan University Hospital, No. 19 Hsuchow Road, Taipei 100, Taiwan.
Jau-Min
JM
Wong
Ming-Fang
MF
Yen
Mei-Shu
MS
Lai
Stephen W
SW
Duffy
Robert A
RA
Smith
Tony Hsiu-Hsi
TH
Chen
D000368:Aged; D003113:Colonoscopy / Q000592:standards* / Q000706:statistics & numerical data; D015179:Colorectal Neoplasms / Q000401:mortality / Q000473:pathology*; D003198:Computer Simulation; D003955:Diagnostic Tests, Routine; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D008390:Markov Chains; D008403:Mass Screening / Q000592:standards*; D008875:Middle Aged; D009367:Neoplasm Staging; D012307:Risk Factors; D016019:Survival Analysis; D013997:Time Factors