Table 2.
Associations between antibiotics use and risk of colorectal cancer by tumor site
| Tumor site and antibiotics usea | Including all antibiotics use before diagnosis |
Excluding antibiotics use during the 2 years preceding CRC diagnosis |
||
|---|---|---|---|---|
| No. of cases/controls | Adjusted OR (95% CI)b | No. of cases/controls | Adjusted OR (95% CI)b | |
| Colorectum | ||||
| No use | 9 728/54 641 | 1 (Referent) | 13 714/70 136 | 1 (Referent) |
| Low | 4 209/21 044 | 1.11 (1.07 to 1.15) | 4 745/23 468 | 1.02 (0.98 to 1.06) |
| Moderate | 18 316/88 401 | 1.15 (1.12 to 1.18) | 16 536/81 914 | 1.01 (0.98 to 1.04) |
| High | 6 554/30 774 | 1.17 (1.13 to 1.21) | 4 414/21 982 | 0.98 (0.94 to 1.02) |
| Very high | 1 738/7 860 | 1.17 (1.10 to 1.24) | 1 136/5 220 | 1.02 (0.95 to 1.09) |
| Ptrendc | <.001 | .97 | ||
| Colon | ||||
| No use | 6 019/35 848 | 1 (Referent) | 8 739/46 146 | 1 (Referent) |
| Low | 2 727/14 144 | 1.13 (1.08 to 1.19) | 3 138/15 874 | 1.03 (0.98 to 1.07) |
| Moderate | 12 459/59 432 | 1.23 (1.19 to 1.27) | 11 356/55 108 | 1.06 (1.02 to 1.09) |
| High | 4 721/21 130 | 1.28 (1.23 to 1.34) | 3 128/15 230 | 1.02 (0.97 to 1.07) |
| Very high | 1 248/5 316 | 1.27 (1.19 to 1.37) | 813/3 512 | 1.07 (0.98 to 1.17) |
| Ptrendc | <.001 | .009 | ||
| Proximal colon | ||||
| No use | 3 129/18 991 | 1 (Referent) | 4 492/24 557 | 1 (Referent) |
| Low | 1 520/7 707 | 1.18 (1.10 to 1.26) | 1 707/8 638 | 1.07 (1.00 to 1.14) |
| Moderate | 6 685/32 436 | 1.23 (1.17 to 1.29) | 6 218/30 191 | 1.09 (1.05 to 1.14) |
| High | 2 663/11 725 | 1.30 (1.22 to 1.38) | 1 840/8 452 | 1.10 (1.03 to 1.17) |
| Very high | 768/2 966 | 1.35 (1.23 to 1.49) | 508/1 987 | 1.17 (1.05 to 1.31) |
| Ptrendc | <.001 | <.001 | ||
| Distal colon | ||||
| No use | 2 771/16 128 | 1 (Referent) | 4 051/20 682 | 1 (Referent) |
| Low | 1 174/6 153 | 1.10 (1.02 to 1.19) | 1 385/6 902 | 1.00 (0.94 to 1.07) |
| Moderate | 5 526/25 810 | 1.23 (1.17 to 1.29) | 4 925/23 813 | 1.03 (0.98 to 1.08) |
| High | 1 941/8 974 | 1.25 (1.17 to 1.34) | 1 212/6 465 | 0.93 (0.86 to 1.00) |
| Very high | 452/2 255 | 1.16 (1.03 to 1.30) | 291/1 458 | 0.96 (0.84 to 1.10) |
| Ptrendc | <.001 | .56 | ||
| Rectum | ||||
| No use | 3 709/18 793 | 1 (Referent) | 4 975/23 990 | 1 (Referent) |
| Low | 1 482/6 900 | 1.08 (1.01 to 1.15) | 1 607/7 594 | 1.01 (0.94 to 1.07) |
| Moderate | 5 857/28 969 | 1.02 (0.97 to 1.07) | 5 180/26 806 | 0.92 (0.88 to 0.96) |
| High | 1 833/9 644 | 0.96 (0.90 to 1.03) | 1 286/6 752 | 0.91 (0.84 to 0.97) |
| Very high | 490/2 544 | 0.98 (0.88 to 1.09) | 323/1 708 | 0.91 (0.80 to 1.04) |
| Ptrendc | .44 | <.001 | ||
Antibiotics use was categorized as no use (no prescriptions during the study period), low (1-10 days), moderate (11-60 days), high (61-180 days), and very high (>180 days) use, using defined daily doses. CI = confidence interval; CRC = colorectal cancer; OR = odds ratio.
Odds ratios, conditioned on matching factors (age, sex, county) and adjusted for socioeconomic factors (level of education, country of birth, marital status) and health-care utilizations prior the 2 years preceding colorectal cancer diagnosis (number of specialist visits and hospitalizations).
The Ptrend represents a trend test in which the 5 categories of antibiotics use were included in the model as a continuous variable.