Table 7.
Outcomes for exposed group by type of cancer and age at first CT exposure, based on a one year lag period
| Age at first exposure (years) | P for trend | ||||
|---|---|---|---|---|---|
| 0-4 | 5-9 | 10-14 | 15-19 | ||
| Observed no of cancers in exposed group, IRR (95% CI)* | |||||
| Brain cancer | 31, 3.01 (2.11 to 4.30) | 53, 3.03 (2.30 to 3.99) | 68, 1.93 (1.51 to 2.46) | 131, 1.82 (1.53 to 2.18) | 0.001 |
| After brain CT | 27, 3.10 (2.12 to 4.54) | 40, 2.93 (2.14 to 4.01) | 48, 2.08 (1.56 to 2.78) | 95, 2.29 (1.86 to 2.82) | 0.09 |
| After other CT | 4, 2.52 (0.94 to 6.72) | 13, 3.37 (1.95 to 5.83) | 20, 1.63 (1.04 to 2.53) | 36, 1.17 (0.84 to 1.63) | 0.002 |
| All solid cancers except brain cancer | 53, 1.76 (1.34 to 2.31) | 152, 1.30 (1.10 to 1.52) | 520, 1.16 (1.06 to 1.26) | 1499, 1.18 (1.12 to 1.24) | 0.06 |
| Leukaemias and myelodysplasias | 20, 0.95 (0.61 to 1.48) | 32, 1.04 (0.73 to 1.48) | 72, 1.26 (1.00 to 1.60) | 122, 1.36 (1.14 to 1.64) | 0.06 |
| Other lymphoid and haematopoietic cancers | 22, 1.83 (1.20 to 2.79) | 49, 1.29 (0.97 to 1.71) | 118, 1.17 (0.98 to 1.41) | 208, 1.10 (0.95 to 1.26) | 0.04 |
| All cancers | 126, 1.72 (1.44 to 2.05) | 286, 1.40 (1.25 to 1.58) | 778, 1.21 (1.13 to 1.30) | 1960, 1.21 (1.16 to 1.27) | <0.001 |
| All solid cancers, except brain cancer after brain CT | 57, 1.80 (1.39 to 2.33) | 165, 1.36 (1.17 to 1.59) | 540, 1.17 (1.07 to 1.27) | 1535, 1.18 (1.12 to 1.24) | 0.01 |
| All cancers, except brain cancer after brain CT | 99, 1.53 (1.26 to 1.86) | 246, 1.29 (1.14 to 1.47) | 730, 1.18 (1.10 to 1.27) | 1865, 1.18 (1.13 to 1.24) | 0.03 |
| No of excess cancers in exposed group, EIR per 100 000 person years (95% CI)* | |||||
| Brain cancer | 20.7, 4.37 (2.07 to 6.68) | 35.4, 3.50 (2.09 to 4.91) | 32.6, 1.71 (0.86 to 2.56) | 58.6, 1.89 (1.17 to 2.62) | 0.16 |
| after brain CT | 18.3, 4.58 (2.03 to 7.13) | 26.3, 3.36 (1.77 to 4.94) | 24.9, 2.06 (0.94 to 3.18) | 53.3, 3.05 (1.96 to 4.15) | 0.41 |
| after other CT | 2.4, 3.26 (−2.04 to 8.55) | 9.2, 4.01 (0.91 to 7.11) | 7.7, 1.10 (−0.16 to 2.35) | 5.4, 0.40 (−0.47 to 1.27) | 0.03 |
| All solid cancers except brain cancer | 22.9, 4.83 (1.82 to 7.84) | 34.6, 3.42 (1.04 to 5.81) | 70.6, 3.70 (1.36 to 6.05) | 227.7, 7.36 (4.91 to 9.81) | 0.04 |
| Leukaemias and myelodysplasias | −1.0, −0.22 (−2.07 to 1.64) | 1.3, 0.13 (−0.97 to 1.22) | 15.0, 0.79 (−0.09 to 1.66) | 32.6, 1.05 (0.35 to 1.75) | 0.01 |
| Other lymphoid and haematopoietic cancers | 10.0, 2.11 (0.17 to 4.05) | 11.0, 1.08 (−0.27 to 2.44) | 17.6, 0.93 (−0.19 to 2.04) | 18.8, 0.61 (−0.31 to 1.52) | 0.32 |
| All cancers | 52.6, 11.10 (6.45 to 15.74) | 82.3, 8.14 (4.86 to 11.41) | 135.8, 7.12 (4.25 to 9.99) | 337.7, 10.91 (8.11 to 13.72) | 0.41 |
| All solid cancers, except brain cancer after brain CT | 25.3, 5.34 (1.55 to 9.13) | 43.8, 4.33 (1.55 to 7.10) | 78.2, 4.10 (1.61 to 6.60) | 233.1, 7.53 (4.98 to 10.09) | 0.21 |
| All cancers, except brain cancer after brain CT | 34.3, 7.23 (2.59 to 11.88) | 56.0, 5.54 (2.26 to 8.82) | 110.9, 5.82 (2.95 to 8.69) | 284.5, 9.19 (6.39 to 12.00) | 0.22 |
IRR=incidence rate ratio, exposed v unexposed; EIR=absolute excess incidence rate compared with rates in unexposed group.
*IRR, EIR, and number of excess cancers calculated after stratification for age, sex, and year of birth.