Table 3.

Estimated values (confidence interval) for sensitivity of FOBT and duration of preclinical CRC for three sensitivity hypotheses

Parameters	Hypothesis A	Hypothesis B	Hypothesis C
Average duration in years
Dukes A	1.6 (1.4-1.8)	3.8 (3.3-4.2)	2.5 (2.3-2.8)
Dukes B	2.1 (1.9-2.5)	2.4 (2.1-2.7)	2.5 (2.2-3.0)
Dukes C	4.0 (3.2-4.6)	3.6 (3.0-4.3)	3.7 (3.1-4.7)
Dukes D	3.2 (2.2-4.3)	2.1 (1.4-2.8)	1.5 (1.2-2.7)
Total*	6.0 (5.2-6.9)	8.0 (7.1-9.0)	6.7 (5.8-7.7)
Sensitivity unrehydrated FOBT (%):†
Dukes A	33 (30-37)	13 (12-16)
Dukes B	33 (30-37)	35 (33-42)
Dukes C	33 (30-37)	38 (36-44)
Dukes D	33 (30-37)	66 (61-76)
Stage of clinical diagnosis			51 (47-65)
Earlier stages			19 (16-25)

FOBT: Fecal Occult Blood Test

CRC: Colorectal Cancer

Hypothesis A: same sensitivity of FOBT for all cancer stages.

Hypothesis B: sensitivity different for each cancer stage.

Hypothesis C: sensitivity of FOBT different in stage of clinical diagnosis than in earlier stages.

^*Calculated as (% in stage A * duration A) + (% in stage B * duration A+B) + (% in stage B * duration A+B+C) + (% in stage D * duration A+B+C+D)

^†For the Minnesota trial sensitivity of rehydrated FOBT were: 28% for Hypothesis A; 10% Dukes A, 26% Dukes B, 56% Dukes C and 63% Dukes D for Hypothesis B; 55% stage of clinical diagnosis, 10% earlier stages for Hypothesis C.