Table 4.
HR and 95% CI for the associations between risk factors and 5-year recurrence by tumor molecular subtype
| Risk factora | Recurrence after 5 years | P-hetd | |||||||
|---|---|---|---|---|---|---|---|---|---|
| A-like | B-like | HER2-enriched | Triple-negative | ||||||
| N/events | HR (95% CI) | N/events | HR (95% CI) | N/events | HR (95% CI) | N/events | HR (95% CI) | ||
| Ethnicity | |||||||||
| Chinese | 567/34 | 1.00 (reference) | 435/49 | 1.00 (reference) | 180/30 | 1.00 (reference) | 275/38 | 1.00 (reference) | 0.96 |
| Malay | 204/8 | 1.01 (0.39, 2.60) | 263/30 | 0.81 (0.45, 1.45) | 104/17 | 0.69 (0.31, 1.51) | 155/24 | 1.11 (0.61, 2.02) | |
| Native | 245/16 | 1.17 (0.49, 2.79) | 291/22 | 0.84 (0.46, 1.55) | 103/10 | 0.47 (0.18, 1.23) | 190/22 | 0.67 (0.34, 1.34) | |
| P value | 0.75 | 0.55 | 0.11 | 0.32 | |||||
| Menarche | |||||||||
| ≤ 12 yrs | 344/13 | 1.00 (reference) | 326/38 | 1.00 (reference) | 118/14 | 1.00 (reference) | 190/34 | 1.00 (reference) | 0.07 |
| 13 yrs | 318/17 | 1.55 (0.57, 4.23) | 340/31 | 1.03 (0.58, 1.82) | 148/21 | 1.52 (0.69, 3.33) | 201/24 | 0.72 (0.38, 1.37) | |
| 14 yrs | 163/14 | 2.51 (0.86, 7.33) | 167/21 | 0.81 (0.40, 1.64) | 60/9 | 0.56 (0.16, 1.92) | 111/13 | 0.65 (0.30, 1.43) | |
| ≥ 15 yrs | 184/13 | 3.26 (1.08, 9.92) | 148/11 | 0.77 (0.35, 1.68) | 57/12 | 1.11 (0.38, 3.28) | 113/12 | 0.61 (0.27, 1.36) | |
| P value | 0.02 | 0.41 | 0.81 | 0.18 | |||||
| Parity and BFc | |||||||||
| Nulliparous | 242/19 | 1.00 (reference) | 224/16 | 1.00 (reference) | 77/12 | 1.00 (reference) | 128/19 | 1.00 (reference) | 0.56 |
| Parous and No BF | 133/7 | 0.55 (0.20, 1.50) | 103/14 | 1.86 (0.76, 4.56) | 31/7 | 1.35 (0.39, 4.64) | 64/17 | 1.57 (0.67, 3.66) | |
| Parous and BF | 641/32 | 0.27 (0.12, 0.58) | 662/71 | 1.63 (0.81, 3.28) | 279/38 | 0.58 (0.25, 1.34) | 428/48 | 0.77 (0.39, 1.52) | |
| P value | 0.001 | 0.23 | 0.15 | 0.28 | |||||
| Age at FFPd | |||||||||
| < 25 | 400/13 | 1.00 (reference) | 445/44 | 1.00 (reference) | 183/30 | 1.00 (reference) | 294/41 | 1.00 (reference) | 0.52 |
| ≥ 25 | 374/26 | 1.69 (0.66, 4.34) | 320/41 | 1.32 (0.78, 2.22) | 127/15 | 0.50 (0.21, 1.16) | 197/23 | 0.75 (0.41, 1.39) | |
| P value | 0.27 | 0.28 | 0.10 | 0.36 | |||||
| Family history | |||||||||
| No | 840/42 | 1.00 (reference) | 854/85 | 1.00 (reference) | 338/49 | 1.00 (reference) | 516/66 | 1.00 (reference) | 0.94 |
| Yes | 160/13 | 0.77 (0.29, 2.03) | 119/14 | 1.17 (0.60, 2.28) | 46/7 | 1.24 (0.45, 3.35) | 92/12 | 0.85 (0.43, 1.70) | |
| P value | 0.60 | 0.64 | 0.67 | ||||||
| BMI, kg/m2 | |||||||||
| 18.5–24.9 | 160/6 | 1.00 (referent) | 172/14 | 1.00 (referent) | 68/11 | 1.00 (referent) | 114/16 | 1.00 (referent) | 0.98 |
| < 18.5 | 373/30 | 3.97 (0.91, 17.34) | 336/29 | 1.37 (0.62, 3.03) | 163/21 | 0.50 (0.20, 1.27) | 240/30 | 1.01 (0.51, 2.01) | |
| P value | 0.06 | 0.43 | 0.15 | 0.97 | |||||
| 25–30 | 317/16 | 3.40 (0.75, 15.42) | 301/37 | 2.02 (0.95, 4.29) | 104/15 | 0.70 (0.27, 1.81) | 177/24 | 0.83 (0.39, 1.73) | |
| P value | 0.11 | 0.06 | 0.46 | 0.62 | |||||
| > 30 | 136/5 | 1.65 (0.27, 10.15) | 148/15 | 1.28 (0.53, 3.12) | 38/7 | 1.41 (0.46, 4.27) | 66/13 | 0.89 (0.35, 2.25) | |
| P value | 0.59 | 0.58 | 0.55 | 0.81 | |||||
In bold are variables which met our criteria (P-value < 0.1) for inclusion in multivariate models
aEach risk factor was adjusted for age, ethnicity, BMI, tumor stage, histologic grade, surgery, systemic therapy (endocrine (tamoxifen or AI versus none), chemotherapy (any regimen versus none)) and radiotherapy (received versus none)
bBF breastfeeding
cFFP first full-term pregnancy. Due to sample size considerations age at FFP was dichotomized
dP value for heterogeneity (P-het) of HR estimates according to molecular subtypes