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Table 2 Risk of invasive or in situ breast cancer in relation to pubertal variables

From: Timing of pubertal stages and breast cancer risk: the Breakthrough Generations Study

  Adjusted for attained age   Multivariate-adjusteda  
Pubertal variable Ncases/person-years HR (95% CI)   Ncases/person-years HR (95% CI)  
Age at thelarche, years
≤10 152/53,916 1.22 (1.02,1.47) * 151/53,308 1.23 (1.02, 1.48) *
11 to 12 445/17,5791 Referent   443/173,413 Referent  
≥13 276/120,309 0.82 (0.71,0.96) * 269/118,581 0.80 (0.69, 0.93) **
HR for trend   0.82 (0.74, 0.90) ***   0.81 (0.73, 0.89) ***
Age at menarche, years
≤12 451/171,139 1.03 (0.90,1.17)   449/168,478 1.06 (0.93,1.21)  
13 to 14 449/171,466 Referent   444/168,733 Referent  
≥15 86/38,779 0.81 (0.64,1.02)   83/38,109 0.78 (0.62,0.99) *
HR for trend   0.92 (0.83, 1.01)    0.89 (0.81, 0.99) *
Age at regular periods, years
≤12 213/80,631 0.97 (0.81,1.15)   212/79,450 0.99 (0.83,1.18)  
13 to 14 295/107,008 Referent   292/105,314 Referent  
≥15 105/50,215 0.74 (0.59,0.93) ** 104/49,465 0.74 (0.59,0.92) **
Never had 73/26,114 1.15 (0.89,1.49)   73/25,581 1.16 (0.90,1.50)  
regular periods
HR for trendb   0.90 (0.81, 1.00)    0.88 (0.79, 0.98) *
Age reached adult height, years
≤14 198/73,048 1.20 (0.99,1.45)   198/72,430 1.25 (1.03,1.52) *
15 to 16 212/100,038 Referent   208/98,651 Referent  
≥17 148/69,134 1.06 (0.86,1.31)   148/67,894 1.07 (0.87,1.32)  
HR for trend   0.93 (0.84, 1.04)    0.92 (0.82, 1.02)  
Growth spurt between ages 7 and 11 yearsc
No 956/37,8071 Referent   947/372,171 Referent  
Yes 100/34,784 1.15 (0.94,1.41)   98/34,259 1.12 (0.91,1.38)  
  1. CI ,Confidence interval; HR, Hazard ratio.
  2. *P <0.05; **P <0.01; ***P <0.001.
  3. aAdjusted for attained age, menopausal status, family history of breast cancer in a first-degree relative, adult height, age at first full-term pregnancy (with a term for nulliparous women) and HRT status.
  4. bTest for trend excludes those who had never had a regular period.
  5. cSubjects were classed as having had a growth spurt between ages 7 and 11 years if their height compared with girls of a similar age increased by at least one category from age 7 to 11.