Table 2 Risk of breast cancer subgroups defined by clinico-pathological markers in relation to total duration of breastfeeding
From: Breastfeeding in relation to risk of different breast cancer characteristics
Tumour subgroup | Breastfeeding total in months | Number of cases | Incidence/100000 | RR | RR* |
|---|---|---|---|---|---|
Invasive | |||||
breast cancer** | <4.0 | 80 | 270 | 1.00 | 1.00 |
≥4.0 - <8.0 | 108 | 288 | 1.07 (0.80 - 1.42) | 1.04 (0.77 - 1.40) | |
≥8.0 - <13.0 | 109 | 304 | 1.12 (0.84 - 1.49) | 1.09 (0.80 - 1.48) | |
≥13.0 | 103 | 293 | 1.08 (0.81 - 1.45) | 1.10 (0.78 - 1.54) | |
Missing | 24 | 399 | --- | --- | |
Total | 424 | 294 | p-trend: 0.56 | p-trend:0.45 | |
CIS | |||||
<4.0 | 9 | 30 | 1.00 | 1.00 | |
≥4.0 - <8.0 | 19 | 51 | 1.67 (0.76 - 3.70) | 1.90 (0.84 - 4.30) | |
≥8.0 - <13.0 | 13 | 36 | 1.20 (0.51 - 2.81) | 1.40 (0.57 - 3.46) | |
≥13.0 | 13 | 37 | 1.22 (0.52 - 2.86) | 1.59 (0.60 - 4.21) | |
Missing | 3 | 50 | --- | --- | |
Total | 57 | 40 | p-trend:0.98 | p-trend:0.48 | |
Size ≤20 mm# | |||||
<4.0 | 55 | 186 | 1. 00 | 1.00 | |
≥4.0 - <8.0 | 80 | 214 | 1.15 (0.82 - 1.62) | 1.12 (0.79 - 1.60) | |
≥8.0 - <13.0 | 69 | 192 | 1.03 (0.72 - 1.47) | 0.99 (0.68 - 1.45) | |
≥13.0 | 85 | 241 | 1.30 (0.93 - 1.82) | 1.29 (0.87 - 1.92) | |
Missing | 15 | 249 | --- | --- | |
Total | 304 | 211 | p-trend:0.21 | p-trend:0.24 | |
Size >20 mm | |||||
<4.0 | 25 | 84 | 1.00 | 1.00 | |
≥4.0 - <8.0 | 27 | 72 | 0.85 (0.50 - 1.47) | 0.84 (0.48 - 1.47) | |
≥8.0 - <13.0 | 39 | 109 | 1.28 (0.78 - 2.12) | 1.28 (0.75 - 2.20) | |
≥13.0 | 18 | 51 | 0.61 (0.33 - 1.11) | 0.65 (0.33 - 1.27) | |
Missing | 9 | 150 | --- | --- | |
Total | 118 | 82 | p-trend:0.36 | p-trend:0.63 | |
Axillary lymph | |||||
node neg# | <4.0 | 27 | 91 | 1.00 | 1.00 |
≥4.0 - <8.0 | 32 | 85 | 0.94 (0.56 - 1.56) | 0.91 (0.54 - 1.54) | |
≥8.0 - <13.0 | 34 | 95 | 1.04 (0.63 - 1.72) | 0.99 (0.56 - 1.70) | |
≥13.0 | 31 | 88 | 0.97 (0.58 - 1.62) | 0.90 (0.50 - 1.64) | |
Missing | 5 | 83 | --- | --- | |
Total | 129 | 89 | p-trend:0.99 | p-trend:0.82 | |
Axillary lymph | |||||
node pos | <4.0 | 53 | 179 | 1.00 | 1.00 |
≥4.0 - <8.0 | 72 | 192 | 1.07 (0.75 - 1.53) | 1.05 (0.73 - 1.51) | |
≥8.0 - <13.0 | 71 | 198 | 1.10 (0.77 - 1.57) | 1.08 (0.73 - 1.57) | |
≥13.0 | 71 | 202 | 1.13 (0.79 - 1.61) | 1.18 (0.78 - 1.79) | |
Missing | 19 | 316 | --- | --- | |
Total | 286 | 198 | p-trend: 0.52 | p-trend:0.30 | |
Grade I# | |||||
<4.0 | 27 | 91 | 1.00 | 1.00 | |
≥4.0 - <8.0 | 37 | 99 | 1.08 (0.66 - 1.78) | 1.01 (0.61 - 1.69) | |
≥8.0 - <13.0 | 28 | 78 | 0.85 (0.50 - 1.45) | 0.78 (0.44 - 1.38) | |
≥13.0 | 28 | 80 | 0.87 (0.51 - 1.48) | 0.87 (0.47 - 1.61) | |
Missing | 7 | 116 | --- | --- | |
Total | 127 | 88 | p-trend:0.42 | p-trend:0.71 | |
Grade II | |||||
<4.0 | 33 | 111 | 1.00 | 1.00 | |
≥4.0 - <8.0 | 47 | 125 | 1.12 (0.72 - 1.75) | 1.05 (0.67 - 1.66) | |
≥8.0 - <13.0 | 53 | 148 | 1.32 (0.85 - 2.03) | 1.15 (0.73 - 1.83) | |
≥13.0 | 46 | 131 | 1.17 (0.75 - 1.83) | 0.99 (0.60 - 1.64) | |
Missing | 12 | 199 | --- | --- | |
Total | 191 | 132 | p-trend:0.40 | p-trend:0.97 | |
Grade III## | |||||
<4.0 | 20 | 67 | 1.00 | 1.00 | |
≥4.0 - <8.0 | 23 | 61 | 0.91 (0.45 - 1.66) | 1.00 (0.54 - 1.85) | |
≥8.0 - <13.0 | 28 | 78 | 1.15 (0.65 - 2.05) | 1.43 (0.77 - 2.66) | |
≥13.0 | 29 | 82 | 1.22 (0.69 - 2.16) | 1.74 (0.89 - 3.41) | |
Missing | 5 | 83 | --- | --- | |
Total | 105 | 73 | p-trend:0.34 | p-trend:0.051 |