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Table 5 Postmenopausal breast cancer risk overall and by estrogen receptor (ER) and progesterone receptor (PR) status of breast tumors and changes in physical activity (PA) level among 1,767 breast cancer cases in the Norwegian Women and Cancer Study

From: Physical activity and the risk of postmenopausal breast cancer - the Norwegian Women and Cancer Study

  N cases Overall Breast cancer N casesa ER+/ PR+ N casesa ER+/ PR- N casesa ER-/PR-
Changes in PA levelb     RR (95% CI)c   RR (95% CI)c   RR (95% CI)c
Age 14 to age 30         
Inactive 75 0.78 (0.62, 0.99) 37 0.79 (0.56, 1.10) 9 0.53 (0.27, 1.03) 10 0.91 (0.48, 1.73)
Active to inactive 163 1.18 (1.0, 1.39) 96 1.43 (1.15, 1.78) 27 1.10 (0.74, 1.65) 11 0.72 (0.39, 1.32)
Inactive to active 125 0.81 (0.67,0 .97) 56 0.74 (0.56, 0.97) 20 0.73 (0.46, 1.15) 21 1.16 (0.73. 1.82)
Active 1334 1.0 ref 650 1.0 ref 229 1.0 ref 155 1.0 ref
Age 14 to enrollment         
Inactive 72 0.82 (0.64, 1.03) 34 0.75 (0.53, 1.06) 9 0.63 (0.32, 1.24) 10 1.06 (0.56, 2.03)
Active to inactive 419 1.06 (0.95, 1.20) 203 1.00 (0.85, 1.18) 78 1.29 (0.98, 1.69) 44 1.07 (0.75, 1.52)
Inactive to active 130 0.79 (.66, 0.95) 59 0.71 (0.54, 0.93) 20 0.71 (0.45, 1.13) 21 1.12 (0.70, 1.77)
Active 1091 1.0 ref 550 1.0 ref 179 1.0 ref 124 1.0 ref
Age 30 to enrollment         
Inactive 146 1.06 (0.89, 1.27) 79 1.15 (0.91, 1.46) 24 1.05 (0.69, 1.62) 11 0.72 (0.39, 1.33)
Active to inactive 347 1.04 (0.92, 1.18) 160 0.95 (0.79, 1.13) 64 1.27 (0.95, 1.69) 43 1.18 (0.83, 1.67)
Inactive to active 94 1.01 (0.82, 1.25) 55 1.19 (0.90, 1.57) 12 0.77 (0.43, 1.37) 11 1.01 (0.54, 1.87)
Active 1136 1.0 ref 562 1.0 ref 188 1.0 ref 136 1.0 ref
  1. aThe total number of breast cancer does not add up caused by missing information on PA at younger ages, age 14 to age 30 n = 77,272, age 14 to enrollment n = 77,623 and age 30 to enrollment n = 78,477.
  2. bInactive: very low or low PA level, Active: moderate, high or very high PA level.
  3. cThe multivariable model with RR and 95% CI used the attained age as the underlying time variable. Covariates adjusted for in the model were height, body mass index, smoking status, duration of smoking (pack years), age at smoking initiation, age at menarche, use of oral contraceptives, age at first birth, parity, use of hormone replacement therapy, self-reported disease and history of breast cancer in the participant’s mother.
  4. RR: relative risks; CI: confidence intervals.