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Table 5.

ORs and 95% CIs for an association between low-, moderate-, and high-intensity outdoor activity episodes at ages 10 to 19, 20 to 29, and 45 to 54, and breast cancer in cases and controls

Cases (%)Controls (%)OR* (95% CI)OR (95% CI)
Low-intensity outdoor activity     
    Ages 10-19     
        <1 285 (31) 250 (23) 1.00 1.00 
        1-98 215 (23) 259 (24) 0.76 (0.59-0.97) 0.80 (0.61-1.04) 
        99-313 216 (23) 287 (26) 0.69 (0.54-0.88) 0.76 (0.58-0.99) 
        314+ 209 (23) 295 (27) 0.65 (0.51-0.83) 0.69 (0.53-0.91) 
    Ages 20-29     
        <1 295 (32) 302 (27) 1.00 1.00 
        1-80 188 (20) 237 (21) 0.83 (0.65-1.07) 0.88 (0.68-1.15) 
        81-240 268 (29) 337 (31) 0.83 (0.66-1.04) 0.90 (0.70-1.14) 
        241+ 179 (19) 229 (21) 0.81 (0.63-1.05) 0.85 (0.65-1.11) 
    Ages 45-54     
        <64 93 (23) 108 (23) 1.00 1.00 
        64-143 100 (25) 115 (25) 1.01 (0.69-1.49) 1.04 (0.70-1.56) 
        144-287 97 (24) 116 (25) 0.97 (0.66-1.43) 0.90 (0.60-1.36) 
        288+ 114 (28) 124 (27) 1.07 (0.73-1.56) 1.01 (0.68-1.50) 
Moderate-intensity outdoor activity     
    Ages 10-19     
        <295 263 (28) 246 (22) 1.00 1.00 
        295-672 226 (24) 297 (27) 0.72 (0.56-0.92) 0.70 (0.54-0.90) 
        673-840 253 (27) 272 (25) 0.87 (0.68-1.12) 0.87 (0.67-1.12) 
        841+ 187 (20) 287 (26) 0.60 (0.47-0.78) 0.58 (0.44-0.76) 
    Ages 20-29     
        <225 275 (29) 236 (21) 1.00 1.00 
        225-540 234 (25) 292 (26) 0.69 (0.54-0.88) 0.74 (0.57-0.95) 
        541-840 237 (25) 304 (27) 0.66 (0.52-0.85) 0.68 (0.53-0.88) 
        841+ 191 (20) 280 (25) 0.57 (0.44-0.73) 0.59 (0.45-0.77) 
    Ages 45-54     
        <240 94 (14) 116 (15) 1.00 1.00 
        240-504 182 (27) 195 (25) 1.14 (0.81-1.60) 1.10 (0.77-1.56) 
        504-839 144 (21) 170 (22) 1.03 (0.73-1.47) 0.98 (0.68-1.41) 
        840+ 260 (38) 302 (39) 1.04 (0.75-1.44) 0.99 (0.70-1.38) 
High-intensity outdoor activity     
    Ages 10-19     
        <141 290 (31) 222 (20) 1.00 1.00 
        141-416 223 (24) 285 (26) 0.61 (0.48-0.79) 0.62 (0.47-0.80) 
        417-840 216 (23) 300 (27) 0.56 (0.44-0.72) 0.57 (0.44-0.74) 
        841+ 205 (22) 295 (27) 0.55 (0.43-0.710 0.59 (0.45-0.77) 
    Ages 20-29     
        <1 295 (32) 257 (23) 1.00 1.00 
        1-120 229 (24) 291 (26) 0.71 (0.56-0.90) 0.75 (0.59-0.97) 
        121-324 200 (21) 261 (24) 0.68 (0.53-0.88) 0.75 (0.57-0.97) 
        325+ 211 (23) 297 (27) 0.65 (0.51-0.83) 0.70 (0.54-0.90) 
    Ages 45-54     
        <48 67 (15) 72 (13) 1.00 1.00 
        48-119 80 (18) 87 (16) 0.99 (0.63-1.56) 0.96 (0.60-1.53) 
        120-269 129 (29) 163 (30) 0.84 (0.56-1.27) 0.77 (0.51-1.18) 
        270+ 174 (39) 224 (41) 0.83 (0.56-1.22) 0.79 (0.53-1.18) 
Cases (%)Controls (%)OR* (95% CI)OR (95% CI)
Low-intensity outdoor activity     
    Ages 10-19     
        <1 285 (31) 250 (23) 1.00 1.00 
        1-98 215 (23) 259 (24) 0.76 (0.59-0.97) 0.80 (0.61-1.04) 
        99-313 216 (23) 287 (26) 0.69 (0.54-0.88) 0.76 (0.58-0.99) 
        314+ 209 (23) 295 (27) 0.65 (0.51-0.83) 0.69 (0.53-0.91) 
    Ages 20-29     
        <1 295 (32) 302 (27) 1.00 1.00 
        1-80 188 (20) 237 (21) 0.83 (0.65-1.07) 0.88 (0.68-1.15) 
        81-240 268 (29) 337 (31) 0.83 (0.66-1.04) 0.90 (0.70-1.14) 
        241+ 179 (19) 229 (21) 0.81 (0.63-1.05) 0.85 (0.65-1.11) 
    Ages 45-54     
        <64 93 (23) 108 (23) 1.00 1.00 
        64-143 100 (25) 115 (25) 1.01 (0.69-1.49) 1.04 (0.70-1.56) 
        144-287 97 (24) 116 (25) 0.97 (0.66-1.43) 0.90 (0.60-1.36) 
        288+ 114 (28) 124 (27) 1.07 (0.73-1.56) 1.01 (0.68-1.50) 
Moderate-intensity outdoor activity     
    Ages 10-19     
        <295 263 (28) 246 (22) 1.00 1.00 
        295-672 226 (24) 297 (27) 0.72 (0.56-0.92) 0.70 (0.54-0.90) 
        673-840 253 (27) 272 (25) 0.87 (0.68-1.12) 0.87 (0.67-1.12) 
        841+ 187 (20) 287 (26) 0.60 (0.47-0.78) 0.58 (0.44-0.76) 
    Ages 20-29     
        <225 275 (29) 236 (21) 1.00 1.00 
        225-540 234 (25) 292 (26) 0.69 (0.54-0.88) 0.74 (0.57-0.95) 
        541-840 237 (25) 304 (27) 0.66 (0.52-0.85) 0.68 (0.53-0.88) 
        841+ 191 (20) 280 (25) 0.57 (0.44-0.73) 0.59 (0.45-0.77) 
    Ages 45-54     
        <240 94 (14) 116 (15) 1.00 1.00 
        240-504 182 (27) 195 (25) 1.14 (0.81-1.60) 1.10 (0.77-1.56) 
        504-839 144 (21) 170 (22) 1.03 (0.73-1.47) 0.98 (0.68-1.41) 
        840+ 260 (38) 302 (39) 1.04 (0.75-1.44) 0.99 (0.70-1.38) 
High-intensity outdoor activity     
    Ages 10-19     
        <141 290 (31) 222 (20) 1.00 1.00 
        141-416 223 (24) 285 (26) 0.61 (0.48-0.79) 0.62 (0.47-0.80) 
        417-840 216 (23) 300 (27) 0.56 (0.44-0.72) 0.57 (0.44-0.74) 
        841+ 205 (22) 295 (27) 0.55 (0.43-0.710 0.59 (0.45-0.77) 
    Ages 20-29     
        <1 295 (32) 257 (23) 1.00 1.00 
        1-120 229 (24) 291 (26) 0.71 (0.56-0.90) 0.75 (0.59-0.97) 
        121-324 200 (21) 261 (24) 0.68 (0.53-0.88) 0.75 (0.57-0.97) 
        325+ 211 (23) 297 (27) 0.65 (0.51-0.83) 0.70 (0.54-0.90) 
    Ages 45-54     
        <48 67 (15) 72 (13) 1.00 1.00 
        48-119 80 (18) 87 (16) 0.99 (0.63-1.56) 0.96 (0.60-1.53) 
        120-269 129 (29) 163 (30) 0.84 (0.56-1.27) 0.77 (0.51-1.18) 
        270+ 174 (39) 224 (41) 0.83 (0.56-1.22) 0.79 (0.53-1.18) 
*

ORs with 95% CIs adjusted for reference age.

ORs with 95% CIs adjusted for reference age, ethnicity, family history in first-degree relatives, ever breast-fed, education, age menarche, and age at first birth.

Number of outdoor activity episodes derived from reported outdoor activities done for at least 30 min between 9 a.m. and 5 p.m. at least once per month during June, July, and August along with frequency (days per week or month) and duration (number of years) and classified as low, moderate, or high intensity.

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