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Table 3 Cumulative average radon and breast cancer risk stratified by region of residence in NHSII

From: Environmental radon exposure and breast cancer risk in the Nurses’ Health Study II

  Invasive breast cancer ER+/PR+ ER−/PR-
Stratification variablea Cases/p-years HR (95% CI)b p int. Cases/p-years HR (95% CI)b p int. Cases/p-years HR (95% CI)b p int.
Region of residence    0.0002    0.13    0.45
 Northeast
  Radon tertile 1 198/110,392 Referent   94/110,506 Referent   22/110,559 Referent  
  Radon tertile 2 665/376,841 1.05 (0.90, 1.23)   356/377,134 1.19 (0.95, 1.50)   72/377,377 0.96 (0.60, 1.56)  
  Radon tertile 3 494/341,830 0.83 (0.70, 0.99)   262/342,049 0.96 (0.76, 1.23)   69/342,242 0.91 (0.56, 1.49)  
 Midwest
  Radon tertile 1 158/105,523 Referent   87/105,584 Referent   14/105,661 Referent  
  Radon tertile 2 441/311,230 0.96 (0.80, 1.15)   241/311,433 0.95 (0.74, 1.21)   73/311,597 1.77 (1.00, 3.14)  
  Radon tertile 3 616/391,334 1.09 (0.91, 1.29)   301/391,619 0.96 (0.76, 1.22)   96/391,793 1.86 (1.06, 3.26)  
 West
  Radon tertile 1 504/308,674 Referent   279/308,883 Referent   62/309,064 Referent  
  Radon tertile 2 94/48,620 1.19 (0.95, 1.49)   59/48,653 1.41 (1.06, 1.89)   8/48,713 0.72 (0.34, 1.53)  
  Radon tertile 3 53/20,194 1.47 (1.10, 1.97)   23/20,223 1.22 (0.80, 1.88)   7/20,239 1.52 (0.69, 3.37)  
 South
  Radon tertile 1 464/300,872 Referent   224/301,096 Referent   50/301,245 Referent  
  Radon tertile 2 158/102,885 0.95 (0.79, 1.14)   76/102,968 0.95 (0.73, 1.23)   23/103,014 1.27 (0.77, 2.10)  
  Radon tertile 3 110/77,355 0.91 (0.74, 1.13)   64/77,389 1.11 (0.84, 1.47)   17/77,433 1.26 (0.72, 2.19)  
  1. Abbreviations: p int. p-value for interaction, p-years person-years
  2. a Radon tertile 1: <33.3 Bq/m3; tertile 2: ≥33.3–57.4 Bq/m3; tertile 3: ≥57.4 Bq/m3
  3. b Models are not adjusted for the stratifying variable. Models are adjusted for age, race, Census tract median home value, Census tract median income, marital status, living arrangements, individual-level income, family history of breast cancer, screening mammography, personal history of biopsy-confirmed BBD, age at menarche, parity, age at first birth, lactation, menopausal status and hormone use (among postmenopausal women only), height, BMI at age 18, change in BMI since age 18, smoking status, physical activity, adult alcohol consumption, PM2.5, population density