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Table 2 Associations between cumulative average radon and breast cancer risk in NHSII from 1989 to 2013 (n = 112,639)

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

Outcomea Cases (n) Person-years (n) Basicb
HR (95% CI)
Fully adjustedc
HR (95% CI)
Invasive breast cancer
 Radon quintile 1 803 496,494 Referent Referent
 Radon quintile 2 810 503,957 1.03 (0.93, 1.13) 1.02 (0.92, 1.14)
 Radon quintile 3 797 503,121 1.01 (0.92, 1.12) 1.02 (0.90, 1.14)
 Radon quintile 4 745 499,349 0.94 (0.85, 1.04) 0.96 (0.85, 1.08)
 Radon quintile 5 811 499,773 1.02 (0.93, 1.13) 1.06 (0.94, 1.21)
p for trend    0.96 0.30
 Continuous radon (per IQR increase)d 3966 2,502,695 0.99 (0.96, 1.02) 1.01 (0.97, 1.04)
ER+
 Radon quintile 1 490 496,797 Referent Referent
 Radon quintile 2 471 504,288 0.98 (0.87, 1.12) 0.99 (0.87, 1.14)
 Radon quintile 3 498 503,420 1.04 (0.92, 1.18) 1.07 (0.91, 1.24)
 Radon quintile 4 439 499,621 0.91 (0.80, 1.03) 0.96 (0.82, 1.12)
 Radon quintile 5 475 500,089 0.98 (0.86, 1.11) 1.05 (0.89, 1.23)
p for trend    0.53 0.66
 Continuous radon (per IQR increase)d 2373 2,504,215 0.99 (0.95, 1.03) 1.01 (0.96, 1.05)
ER-
 Radon quintile 1 101 497,123 Referent Referent
 Radon quintile 2 112 504,612 1.11 (0.85, 1.46) 1.13 (0.84, 1.51)
 Radon quintile 3 125 503,741 1.24 (0.96, 1.62) 1.27 (0.92, 1.74)
 Radon quintile 4 114 499,939 1.14 (0.87, 1.49) 1.17 (0.84, 1.62)
 Radon quintile 5 133 500,402 1.32 (1.02, 1.72) 1.34 (0.97, 1.86)
p for trend    0.06 0.15
 Continuous radon (per IQR increase)d 585 2,505,817 1.05 (0.97, 1.13) 1.03 (0.95, 1.12)
ER+/PR+
 Radon quintile 1 417 496,859 Referent Referent
 Radon quintile 2 420 504,332 1.03 (0.90, 1.18) 1.06 (0.91, 1.23)
 Radon quintile 3 441 503,469 1.09 (0.95, 1.24) 1.13 (0.96, 1.33)
 Radon quintile 4 384 499,675 0.94 (0.81, 1.08) 1.01 (0.85, 1.19)
 Radon quintile 5 412 500,148 1.00 (0.87, 1.15) 1.10 (0.92, 1.30)
p for trend    0.61 0.60
 Continuous radon (per IQR increase)d 2074 2,504,483 0.99 (0.95, 1.04) 1.01 (0.97, 1.06)
ER−/PR-
 Radon quintile 1 89 497,137 Referent Referent
 Radon quintile 2 93 504,633 1.05 (0.79, 1.41) 1.07 (0.78, 1.46)
 Radon quintile 3 104 503,763 1.18 (0.89, 1.57) 1.19 (0.85, 1.68)
 Radon quintile 4 104 499,946 1.19 (0.89, 1.58) 1.20 (0.85, 1.69)
 Radon quintile 5 123 500,409 1.41 (1.07, 1.85) 1.38 (0.97, 1.96)
p for trend    0.01 0.05
 Continuous radon (per IQR increase)d 513 2,505,889 1.08 (0.99, 1.16) 1.05 (0.96, 1.15)
ER+/PR-
 Radon quintile 1 70 497,167 Referent Referent
 Radon quintile 2 47 504,679 0.69 (0.48, 1.00) 0.62 (0.41, 0.93)
 Radon quintile 3 53 503,818 0.77 (0.54, 1.11) 0.66 (0.42, 1.02)
 Radon quintile 4 53 499,984 0.76 (0.53, 1.09) 0.67 (0.43, 1.04)
 Radon quintile 5 62 500,458 0.87 (0.61, 1.22) 0.75 (0.48, 1.18)
p for trend    0.88 1.00
 Continuous radon (per IQR increase)d 285 2,506,105 0.97 (0.87, 1.09) 0.98 (0.86, 1.11)
ER−/PR−/HER2-
 Radon quintile 1 49 497,173 Referent Referent
 Radon quintile 2 53 504,676 1.09 (0.74, 1.60) 1.09 (0.71, 1.67)
 Radon quintile 3 52 503,820 1.07 (0.72, 1.58) 1.06 (0.67, 1.68)
 Radon quintile 4 61 499,980 1.25 (0.86, 1.83) 1.24 (0.78, 1.97)
 Radon quintile 5 78 500,452 1.61 (1.12, 2.31) 1.52 (0.96, 2.41)
p for trend    0.003 0.02
 Continuous radon (per IQR increase)d 293 2,506,101 1.12 (1.01, 1.24) 1.09 (0.97, 1.23)
  1. a Radon quintile 1: <27.0 Bq/m3; quintile 2: ≥27.0–37.7 Bq/m3; quintile 3: ≥37.7–50.1 Bq/m3; quintile 4: ≥50.1–74.9 Bq/m3; quintile 5: ≥74.9 Bq/m3
  2. b Adjusted for age, race
  3. c Additionally adjusted for Census tract median home value, Census tract median income, marital status, living arrangements, individual-level income, region of residence, 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
  4. d An IQR increase in cumulative average radon is 37.3 Bq/m3