Table 4.
Observed and expected screen-detected CRC, stage distribution of screen-detected cancers by phase for first and consecutive rounds and interval cancers and chi-square statistic for three hypotheses for FOBT sensitivity, three trials aggregated
| Outcome | Observed | Expected | ||
|---|---|---|---|---|
| Hypothesis A 6 parameters | Hypothesis B 12 parameters | Hypothesis C 8 parameters | ||
| Screen-detected CRC, round 1 | ||||
| Cases (rate per 1,000 persons screened) | 247 (2.21) | 256 (2.29) | 249 (2.23) | 256 (2.29) |
| Cases (%) Dukes A | 116 (48) | 91 (38)* | 93 (39)† | 101 (42) |
| Cases (%) Dukes B | 60 (25) | 76 (32) | 69 (29) | 76 (32) |
| Cases (%) Dukes C | 52 (22) | 59 (24) | 63 (26) | 53 (22) |
| Cases (%) Dukes D | 12 (5) | 14 (6) | 15 (6) | 11 (5) |
| Screen-detected CRC, consecutive rounds | ||||
| Cases (rate) per 1,000 persons screened | 492 (1.56) | 531 (1.68) | 529 (1.68) | 522 (1.66) |
| Cases (%) Dukes A | 178 (39) | 204 (45) | 202 (44) | 202 (44) |
| Cases (%) Dukes B | 157 (34) | 137 (30) | 134 (29)† | 142 (31) |
| Cases (%) Dukes C | 98 (21) | 94 (21) | 101 (22) | 92 (20) |
| Cases (%) Dukes D | 25 (5) | 23 (5) | 21 (5) | 22 (5) |
| Interval cancers (rate) in first two years after screening per 1,000 person years | 369 (0.73) | 432 (0.85)* | 421 (0.83)† | 386 (0.76) |
| Chi-square statistic# | 83* | 76* | 73† | |
| Akaike Information Criterion# | -10,569 | -10,563 | -10,582 | |
CRC: Colorectal Cancer
FOBT: Fecal Occult Blood Test
*
Expected outcome significantly different from observed (p < 0.01)
†
Expected outcome significantly different from observed (p < 0.05)
#
Based on 59 trial specific outcomes
Hypothesis A: Same sensitivity for all cancer stages
Hypothesis B: Sensitivity different for each cancer stage
Hypothesis C: Sensitivity is higher in stage of clinical diagnosis