Risk of gastrointestinal cancers in patients with breast cancer, by treatment during the first year after breast cancer diagnosis
| Observed/expected | Incidence rate per 100 000 person years (95% CI) | Standardised incidence ratio (95% CI) | |
| Upper gastrointestinal cancers | |||
| Radiotherapy | |||
| No | 163/130 | 45 (38 to 52) | 1.26 (1.07 to 1.47) |
| Yes | 116/93 | 38 (31 to 45) | 1.25 (1.03 to 1.50) |
| Chemotherapy | |||
| No | 221/184 | 46 (40 to 52) | 1.20 (1.05 to 1.37) |
| Yes | 58/39 | 31 (23 to 40) | 1.51 (1.14 to 1.95) |
| Tamoxifen therapy | |||
| No | 224/180 | 41 (35 to 46) | 1.24 (1.09 to 1.42) |
| Yes | 55/42 | 47 (35 to 59) | 1.30 (0.98 to 1.70) |
| Aromatase inhibitor treatment* | |||
| No | † | 34 (25 to 43) | 1.03 (0.78 to 1.35) |
| Yes | † | 131 (−50 to 312) | 2.70 (0.33 to 9.74) |
| Lumpectomy‡ | |||
| No | 96/74 | 46 (37 to 55) | 1.30 (1.05 to 1.59) |
| Yes | 104/89 | 37 (30 to 44) | 1.16 (0.95 to 1.41) |
| Mastectomy‡ | |||
| No | 84/79 | 34 (27 to 42) | 1.07 (0.85 to 1.32) |
| Yes | 116/84 | 47 (38 to 55) | 1.38 (1.14 to 1.65) |
| Lower gastrointestinal cancers | |||
| Radiotherapy | |||
| No | 810/771 | 225 (210 to 241) | 1.05 (0.98 to 1.13) |
| Yes | 619/530 | 202 (186 to 217) | 1.17 (1.08 to 1.26) |
| Chemotherapy | |||
| No | 1168/1092 | 242 (228 to 256) | 1.07 (1.01 to 1.13) |
| Yes | 261/208 | 141 (124 to 159) | 1.25 (1.11 to 1.42) |
| Tamoxifen therapy | |||
| No | 1158/1049 | 211 (199 to 223) | 1.10 (1.04 to 1.17) |
| Yes | 271/251 | 231 (204 to 259) | 1.08 (0.95 to 1.21) |
| Aromatase inhibitor treatment* | |||
| No | † | 234 (210 to 258) | 1.22 (1.10 to 1.35) |
| Yes | † | 196 (−26 to 418) | 0.65 (0.13 to 1.88) |
| Lumpectomy‡ | |||
| No | 499/443 | 237 (217 to 258) | 1.13 (1.03 to 1.23) |
| Yes | 582/517 | 205 (189 to 222) | 1.13 (1.04 to 1.22) |
| Mastectomy‡ | |||
| No | 507/456 | 207 (189 to 225) | 1.11 (1.02 to 1.21) |
| Yes | 574/504 | 231 (212 to 250) | 1.14 (1.05 to 1.24) |
| Other gastrointestinal cancers | |||
| Radiotherapy | |||
| No | 263/243 | 73 (64 to 82) | 1.08 (0.96 to 1.22) |
| Yes | 153/165 | 50 (42 to 58) | 0.92 (0.78 to 1.08) |
| Chemotherapy | |||
| No | 355/345 | 74 (66 to 81) | 1.03 (0.92 to 1.14) |
| Yes | 61/63 | 33 (25 to 41) | 0.97 (0.74 to 1.24) |
| Tamoxifen therapy | |||
| No | 351/329 | 64 (57 to 71) | 1.07 (0.96 to 1.19) |
| Yes | 65/80 | 56 (42 to 69) | 0.82 (0.63 to 1.04) |
| Aromatase inhibitor treatment* | |||
| No | 86/92 | 54 (43 to 66) | 0.93 (0.75 to 1.15) |
| Yes | † | ||
| Lumpectomy‡ | |||
| No | 142/139 | 68 (56 to 79) | 1.02 (0.86 to 1.21) |
| Yes | 159/160 | 56 (47 to 65) | 0.99 (0.84 to 1.16) |
| Mastectomy‡ | |||
| No | 145/141 | 59 (50 to 69) | 1.03 (0.87 to 1.21) |
| Yes | 156/158 | 63 (53 to 73) | 0.99 (0.84 to 1.16) |
*Restricted to 2007 onwards due to limitations in data availability.
†Observed and expected numbers are not reported due to too few events.
‡Restricted to 1996 onwards due to limitations in data availability.