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Table 3

Phytoestrogen consumption and thyroid cancer risk among women participating in the Bay Area Thyroid Cancer Study

Phytoestrogen (μg/day)CasesControlsORa95% CIORb95% CI
Isoflavones       
 Genistein       
  <525 106 108 1.0  1.0  
  525–887 145 109 1.3 0.89–1.9 1.3 0.88–2.0 
  888–1471 135 109 1.1 0.77–1.7 1.3 0.86–2.0 
  1472–3680 121 109 0.97 0.65–1.4 1.1 0.72–1.7 
  ≥3681 83 109 0.65 0.42–1.0 0.70 0.44–1.1 
  Trend across quintiles   P = 0.02  P = 0.14  
  Per 500 μg/day   0.98 0.97–0.99 0.98 0.96–0.99 
 Daidzein       
  <469 112 108 1.0  1.0  
  470–749 128 109 1.1 0.77–1.6 1.0 0.70–1.6 
  750–1235 140 109 1.1 0.78–1.7 1.3 0.85–1.9 
  1236–3596 131 109 0.92 0.62–1.4 1.0 0.67–1.6 
  ≥3597 79 109 0.60 0.39–0.92 0.65 0.40–1.0 
  Trend across quintiles   P = 0.02  P = 0.15  
  Per 500 μg/day   0.97 0.96–0.99 0.97 0.96–0.99 
 Biochanin A       
  <11 110 108 1.0  1.0  
  12–20 115 109 1.0 0.69–1.5 1.0 0.69–1.6 
  21–33 121 109 1.0 0.69–1.5 0.97 0.64–1.5 
  34–51 100 109 0.82 0.55–1.2 0.79 0.52–1.2 
  ≥52 144 109 1.2 0.78–1.7 1.1 0.72–1.7 
  Trend across quintiles   P = 0.78  P = 0.95  
  Per 10 μg/day   1.02 0.98–1.05 1.01 0.98–1.05 
 Formononetin       
  <9 138 108 1.0  1.0  
  10–18 124 109 0.85 0.59–1.2 0.95 0.64–1.4 
  19–28 111 109 0.76 0.53–1.1 0.84 0.57–1.3 
  29–51 115 109 0.77 0.53–1.1 0.85 0.57–1.3 
  ≥52 102 109 0.65 0.44–0.96 0.78 0.51–1.2 
  Trend across quintiles   P = 0.03  P = 0.21  
  Per 10 μg/day   0.97 0.94–0.99 0.98 0.95–1.01 
 Total isoflavones       
  <1046 103 108 1.0  1.0  
  1047–1678 134 109 1.1 0.79–1.7 1.1 0.72–1.6 
  1679–2739 143 109 1.2 0.79–1.7 1.3 0.88–2.0 
  2740–7285 127 109 0.92 0.61–1.4 1.0 0.66–1.6 
  ≥7286 83 109 0.61 0.40–0.94 0.65 0.41–1.0 
  Trend across quintiles   P = 0.02  P = 0.13  
  Per 1000 μg/day   0.98 0.96–0.99 0.98 0.96–0.99 
Coumestans       
 Coumestrol       
  <81.3 118 108 1.0  1.0  
  81.4–123.1 111 109 0.87 0.60–1.3 0.95 0.63–1.4 
  123.2–167.7 101 109 0.76 0.52–1.1 0.71 0.46–1.1 
  167.8–270.4 154 109 1.1 0.78–1.7 1.1 0.71–1.6 
  ≥270.5 106 109 0.73 0.48–1.1 0.78 0.49–1.2 
  Trend across quintiles   P = 0.56  P = 0.55  
  Per 50 μg/day   0.97 0.94–1.01 0.98 0.94–1.2 
Lignans       
 Matairesinol       
  <18 120 108 1.0  1.0  
  19–28 110 109 0.87 0.60–1.3 0.79 0.52–1.2 
  29–38 105 109 0.79 0.54–1.2 0.78 0.51–1.2 
  39–56 140 109 1.0 0.70–1.5 1.0 0.67–1.5 
  ≥57 115 109 0.79 0.52–1.2 0.72 0.46–1.1 
  Trend across quintiles   P = 0.56  P = 0.49  
  Per 10 μg/day   1.00 0.96–1.04 1.00 0.96–1.04 
 Secoisolariciresinol       
  <42 143 108 1.0  1.0  
  43–58 114 109 0.73 0.50–1.1 0.75 0.50–1.1 
  59–80 139 109 0.84 0.58–1.2 0.82 0.55–1.2 
  81–106 101 109 0.57 0.38–0.85 0.58 0.38–0.89 
  ≥107 93 109 0.47 0.31–0.73 0.56 0.35–0.89 
  Trend across quintiles   P = 0.0005  P = 0.009  
  Per 25 μg/day   0.87 0.80–0.94 0.89 0.82–0.96 
 Total Lignans       
  <64.6 124 108 1.0  1.0  
  64.7–90.7 126 109 0.95 0.66–1.4 0.98 0.66–1.5 
  90.8–120.9 122 109 0.85 0.58–1.2 0.73 0.49–1.1 
  121.0–160.9 113 109 0.77 0.52–1.1 0.80 0.52–1.2 
  ≥161.0 105 109 0.63 0.41–0.97 0.68 0.43–1.1 
  Trend across quintiles   P = 0.02  P = 0.07  
  Per 25 μg/day   0.94 0.89–0.99 0.95 0.90–1.00 
Total Phytoestrogens       
 <1252 114 108 1.0  1.0  
 1252–1878 121 109 0.97 0.67–1.4 0.89 0.59–1.3 
 1879–3028 152 109 1.2 0.81–1.7 1.2 0.84–1.9 
 3028–7537 119 109 0.87 0.58–1.3 0.94 0.61–1.4 
 ≥7538 84 109 0.60 0.39–0.93 0.62 0.39–0.99 
 Trend across quintiles   P = 0.03  P = 0.14  
 Per 1000 μg/day   0.98 0.96–0.99 0.98 0.96–0.99 
Phytoestrogen (μg/day)CasesControlsORa95% CIORb95% CI
Isoflavones       
 Genistein       
  <525 106 108 1.0  1.0  
  525–887 145 109 1.3 0.89–1.9 1.3 0.88–2.0 
  888–1471 135 109 1.1 0.77–1.7 1.3 0.86–2.0 
  1472–3680 121 109 0.97 0.65–1.4 1.1 0.72–1.7 
  ≥3681 83 109 0.65 0.42–1.0 0.70 0.44–1.1 
  Trend across quintiles   P = 0.02  P = 0.14  
  Per 500 μg/day   0.98 0.97–0.99 0.98 0.96–0.99 
 Daidzein       
  <469 112 108 1.0  1.0  
  470–749 128 109 1.1 0.77–1.6 1.0 0.70–1.6 
  750–1235 140 109 1.1 0.78–1.7 1.3 0.85–1.9 
  1236–3596 131 109 0.92 0.62–1.4 1.0 0.67–1.6 
  ≥3597 79 109 0.60 0.39–0.92 0.65 0.40–1.0 
  Trend across quintiles   P = 0.02  P = 0.15  
  Per 500 μg/day   0.97 0.96–0.99 0.97 0.96–0.99 
 Biochanin A       
  <11 110 108 1.0  1.0  
  12–20 115 109 1.0 0.69–1.5 1.0 0.69–1.6 
  21–33 121 109 1.0 0.69–1.5 0.97 0.64–1.5 
  34–51 100 109 0.82 0.55–1.2 0.79 0.52–1.2 
  ≥52 144 109 1.2 0.78–1.7 1.1 0.72–1.7 
  Trend across quintiles   P = 0.78  P = 0.95  
  Per 10 μg/day   1.02 0.98–1.05 1.01 0.98–1.05 
 Formononetin       
  <9 138 108 1.0  1.0  
  10–18 124 109 0.85 0.59–1.2 0.95 0.64–1.4 
  19–28 111 109 0.76 0.53–1.1 0.84 0.57–1.3 
  29–51 115 109 0.77 0.53–1.1 0.85 0.57–1.3 
  ≥52 102 109 0.65 0.44–0.96 0.78 0.51–1.2 
  Trend across quintiles   P = 0.03  P = 0.21  
  Per 10 μg/day   0.97 0.94–0.99 0.98 0.95–1.01 
 Total isoflavones       
  <1046 103 108 1.0  1.0  
  1047–1678 134 109 1.1 0.79–1.7 1.1 0.72–1.6 
  1679–2739 143 109 1.2 0.79–1.7 1.3 0.88–2.0 
  2740–7285 127 109 0.92 0.61–1.4 1.0 0.66–1.6 
  ≥7286 83 109 0.61 0.40–0.94 0.65 0.41–1.0 
  Trend across quintiles   P = 0.02  P = 0.13  
  Per 1000 μg/day   0.98 0.96–0.99 0.98 0.96–0.99 
Coumestans       
 Coumestrol       
  <81.3 118 108 1.0  1.0  
  81.4–123.1 111 109 0.87 0.60–1.3 0.95 0.63–1.4 
  123.2–167.7 101 109 0.76 0.52–1.1 0.71 0.46–1.1 
  167.8–270.4 154 109 1.1 0.78–1.7 1.1 0.71–1.6 
  ≥270.5 106 109 0.73 0.48–1.1 0.78 0.49–1.2 
  Trend across quintiles   P = 0.56  P = 0.55  
  Per 50 μg/day   0.97 0.94–1.01 0.98 0.94–1.2 
Lignans       
 Matairesinol       
  <18 120 108 1.0  1.0  
  19–28 110 109 0.87 0.60–1.3 0.79 0.52–1.2 
  29–38 105 109 0.79 0.54–1.2 0.78 0.51–1.2 
  39–56 140 109 1.0 0.70–1.5 1.0 0.67–1.5 
  ≥57 115 109 0.79 0.52–1.2 0.72 0.46–1.1 
  Trend across quintiles   P = 0.56  P = 0.49  
  Per 10 μg/day   1.00 0.96–1.04 1.00 0.96–1.04 
 Secoisolariciresinol       
  <42 143 108 1.0  1.0  
  43–58 114 109 0.73 0.50–1.1 0.75 0.50–1.1 
  59–80 139 109 0.84 0.58–1.2 0.82 0.55–1.2 
  81–106 101 109 0.57 0.38–0.85 0.58 0.38–0.89 
  ≥107 93 109 0.47 0.31–0.73 0.56 0.35–0.89 
  Trend across quintiles   P = 0.0005  P = 0.009  
  Per 25 μg/day   0.87 0.80–0.94 0.89 0.82–0.96 
 Total Lignans       
  <64.6 124 108 1.0  1.0  
  64.7–90.7 126 109 0.95 0.66–1.4 0.98 0.66–1.5 
  90.8–120.9 122 109 0.85 0.58–1.2 0.73 0.49–1.1 
  121.0–160.9 113 109 0.77 0.52–1.1 0.80 0.52–1.2 
  ≥161.0 105 109 0.63 0.41–0.97 0.68 0.43–1.1 
  Trend across quintiles   P = 0.02  P = 0.07  
  Per 25 μg/day   0.94 0.89–0.99 0.95 0.90–1.00 
Total Phytoestrogens       
 <1252 114 108 1.0  1.0  
 1252–1878 121 109 0.97 0.67–1.4 0.89 0.59–1.3 
 1879–3028 152 109 1.2 0.81–1.7 1.2 0.84–1.9 
 3028–7537 119 109 0.87 0.58–1.3 0.94 0.61–1.4 
 ≥7538 84 109 0.60 0.39–0.93 0.62 0.39–0.99 
 Trend across quintiles   P = 0.03  P = 0.14  
 Per 1000 μg/day   0.98 0.96–0.99 0.98 0.96–0.99 
a

Adjusted for age, race/ethnicity, and daily caloric intake.

b

Adjusted for age, race/ethnicity, daily caloric intake, goiter or thyroid nodules, radiation to the head or neck, family history of proliferative thyroid disease, age at menarche, use of oral contraceptives, age at first full-term pregnancy/nulliparity (allowing for separate effects for women <45 and ≥45 years of age), and a composite variable including menopausal status and number of pregnancies in the last 5 years among premenopausal women.

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