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Table 2 Adjusted hazard ratios for the associations between recreational physical activity and invasive breast cancer overall and by subtype

From: Recreational physical activity and risk of triple negative breast cancer in the California Teachers Study

h/wk/y Observed person-years Overall TNBC (ER-/PR-/HER2-)a Luminal A-like (ER+ or PR+ plus HER2-)a
Cases, no. Adjusted HR (95 % CI) Cases, no. Adjusted HR (95 % CI) Cases, no. Adjusted HR (95 % CI)
Total (strenuous plus moderate) RPA
 Long-termc
  ≤0.50 140,148 662 Referent 43 Referent 303 Referent
  0.51–2.50 467,293 1923 0.98 (0.89–1.07) 115 0.83 (0.58–1.18) 886 0.95 (0.83–1.08)
  2.51–4.50 376,903 1319 0.91 (0.82–1.00) 84 0.80 (0.55–1.16) 589 0.84 (0.73–0.97)
  4.51–7.00 289,855 957 0.91 (0.82–1.00) 45 0.58 (0.38–0.89) 445 0.87 (0.75–1.01)
  ≥7.01 327,027 1021 0.90 (0.81–0.99) 61 0.73 (0.49–1.09) 478 0.87 (0.75–1.00)
P trend    0.01   0.11   0.05
 Homogeneity of trends between two subtypes   P = 0.38   
 Baselined
  ≤0.50 355,905 1438 Referent 98 Referent 639 Referent
  0.51–2.50 457,799 1708 0.97 (0.90–1.04) 96 0.77 (0.58–1.02) 787 0.99 (0.89–1.10)
  2.51–4.50 279,320 972 0.90 (0.83–0.98) 61 0.80 (0.58–1.11) 468 0.96 (0.85–1.08)
  4.51–7.00 256,204 901 0.88 (0.81–0.96) 44 0.61 (0.43–0.88) 412 0.89 (0.78–1.01)
  ≥7.01 251,999 863 0.87 (0.80–0.95) 49 0.72 (0.50–1.02) 395 0.88 (0.77–1.00)
P trend    <0.001   0.07   0.01
 Homogeneity of trends between two subtypes   P = 0.34   
Strenuous RPAb
 Long-termc
  ≤0.50 449,871 2069 Referent 122 Referent 936 Referent
  0.51–2.00 522,886 1 900 0.93 (0.87–0.99) 115 0.89 (0.68–1.16) 865 0.92 (0.84–1.02)
  2.01–3.50 293,055 908 0.88 (0.81–0.96) 62 0.93 (0.67–1.29) 430 0.91 (0.80–1.02)
  3.51–5.00 160,273 523 0.99 (0.89–1.09) 27 0.76 (0.49–1.19) 237 0.96 (0.83–1.12)
  ≥5.01 175,143 482 0.87 (0.78–0.97) 22 0.52 (0.31–0.87) 233 0.92 (0.78–1.08)
P trend    0.03   0.02   0.35
 Homogeneity of trends between two subtypes   P = 0.05   
 Baselined
  ≤50 894,810 3654 Referent 224 Referent 1675 Referent
  0.51–2.00 322,058 1066 0.95 (0.89–1.02) 70 1.00 (0.76–1.32) 478 0.91 (0.82–1.01)
  2.01–3.50 157,265 460 0.83 (0.75–0.92) 26 0.73 (0.48–1.11) 216 0.81 (0.70–0.94)
  3.51–5.00 153,597 476 0.94 (0.85–1.04) 14 0.42 (0.24–0.73) 229 0.95 (0.83–1.10)
  ≥5.01 73,497 226 0.90 (0.78–1.04) 14 0.83 (0.47–1.47) 103 0.88 (0.72–1.09)
P trend    0.01   0.01   0.06
 Homogeneity of trends between two subtypes   P = 0.08   
Moderate RPAb
 Long-termc
  ≤0.50 321,926 1314 Referent 79 Referent 630 Referent
  0.51–2.00 582,646 2134 0.99 (0.93–1.07) 134 0.99 (0.74–1.32) 954 0.90 (0.81–1.00)
  2.01–3.50 330,827 1175 0.99 (0.91–1.07) 62 0.85 (0.60–1.20) 550 0.93 (0.83–1.05)
  3.51–5.00 185,859 637 0.97 (0.88–1.07) 30 0.79 (0.51–1.22) 293 0.89 (0.77–1.03)
  ≥5.01 179,970 622 0.99 (0.89–1.10) 43 1.34 (0.89–2.02) 274 0.87 (0.74–1.01)
P trend    0.66   0.42   0.13
 Homogeneity of trends between two subtypes   P = 0.20   
 Baselined
  ≤0.50 519,391 1937 Referent 128 Referent 884 Referent
  0.51–2.00 503,498 1788 1.00 (0.93–1.07) 99 0.82 (0.62–1.07) 808 0.98 (0.89–1.09)
  2.01–3.50 233,772 891 1.04 (0.96–1.13) 51 0.93 (0.66–1.30) 438 1.11 (0.99–1.25)
  3.51–5.00 226,867 799 0.91 (0.83–0.99) 43 0.83 (0.58–1.19) 366 0.90 (0.80–1.03)
  ≥5.01 117,700 467 0.98 (0.88–1.09) 27 0.98 (0.63–1.54) 205 0.95 (0.80–1.11)
P trend    0.19   0.75   0.32
 Homogeneity of trends between two subtypes   P = 0.98   
  1. HRs are from multivariable Cox proportional hazards regression models using age (in days) as the time metric and stratified by age (in years) with the adjustment for race, family history of breast cancer in first-degree relatives, combined age at first full-term pregnancy and parity variable, combined menopausal status and MHT use variable, BMI at baseline, history of smoking, alcohol intake during the past year of baseline, screening mammogram in the past 2 years of baseline, and history of a breast biopsy
  2. Abbreviations: BMI body mass index, CI confidence interval, ER estrogen receptor, HER2 human epidermal growth factor receptor 2, HR hazard ratio, h/wk/y hour/week/year, MHT menopausal hormone therapy, PR progesterone receptor, RPA recreational physical activity, TNBC triple negative breast cancer
  3. aDiagnosed in 1999 and afterward
  4. bAdditionally, strenuous RPA and moderate RPA mutually adjusted
  5. cRPA from high school till age 54 or age at cohort entry, whichever was younger
  6. dRPA during the 3 years prior to baseline
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