Table I.
Characteristics of the participants in the colorectal adenoma and colorectal cancer (CRC) studies
| Adenoma |
CRC |
|||
| Cases (n = 914) | Controls (n = 1185) | Cases (n = 496) | Controls (n = 607) | |
| Sex | ||||
| Male, n (%) | 550 (60.2) | 745 (62.9) | 305 (61.5) | 353 (58.1) |
| Race/ethnicity | ||||
| Japanese American, n (%) | 291 (31.8) | 385 (32.5) | 285 (57.5) | 368 (60.6) |
| European American, n (%) | 428 (46.8) | 564 (47.6) | 140 (28.2) | 159 (26.2) |
| Native Hawaiians, n (%) | 195 (21.4) | 236 (19.9) | 71 (14.3) | 80 (13.2) |
| Recruitment site (procedure)a | ||||
| Kaiser Permanente Hawaii (colonoscopy), n (%) | 392 (42.9) | 359 (30.3) | — | — |
| Kaiser Permanente Hawaii (sigmoidoscopy), n (%) | 435 (47.6) | 601 (50.7) | ||
| PLCO (sigmoidoscopy), n (%) | 87 (9.5) | 225 (19.0) | ||
| Ageb | 61 (55, 68) | 62 (56, 68) | 66 (57, 73) | 67 (57, 74) |
| Smoking statusa | ||||
| Never-smoker, n (%) | 382 (41.8) | 614 (51.8) | 206 (41.5) | 288 (47.4) |
| Past smoker, n (%) | 406 (44.5) | 484 (40.8) | 211 (42.5) | 259 (42.7) |
| Current smokers, n (%) | 125 (13.7) | 87 (7.4) | 79 (16.0) | 60 (9.9) |
| Pack-yearsbc | 22 (8, 42) | 18 (6, 36) | 30 (17, 52) | 22 (9, 42) |
| BMI (kg/m2)b | 26.6 (24.0, 30.7) | 26.1 (23.4, 29.4) | 24.6 (22.2, 27.8) | 24.0 (21.9, 26.6) |
BMI, body mass index; PLCO, Prostate Lung Colorectal and Ovarian.
a
Proportions were significantly different between cases and controls in both studies (P-values < 0.01, χ2 test).
b
Median (interquartile range). The distributions of age in the adenoma study and of pack-years and BMI in both studies were significantly different between cases and controls (P-values ≤ 0.008, Wilcoxon rank-sum test).
c
Pack-years = pack-years of cigarette/cigar/pipe smoking among ever smokers.