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Table 3 Relation of age at menarche to tumor-defined characteristics of breast cancer

From: The influence of menstrual risk factors on tumor characteristics and survival in postmenopausal breast cancer

  Age at menarche, years
  Odds ratio (95% confidence interval)a, b
Tumor characteristic ≤11 > 11 and ≤13 > 13 and ≤14
Tumor size    
   1–10 mm    
   11–20 mm 1.00 (0.65–1.53) 0.96 (0.74–1.25) 1.01 (0.76–1.33)
   ≥21 mm 1.05 (0.64–1.72) 1.43 (1.06–1.92) 1.32 (0.96–1.81)
Grade    
   Low    
   Medium 2.05 (1.00–4.19) 1.47 (1.00–2.15) 1.74 (1.15–2.62)
   High 2.04 (1.01–4.16) 1.55 (1.06–2.26) 1.45 (1.00–2.19)
ER status    
   Positive    
   Negative 1.33 (0.82–2.16) 0.94 (0.68–1.29) 1.15 (0.83–1.61)
PR status    
   Positive    
   Negative 0.86 (0.54–1.36) 0.99 (0.75–1.30) 1.24 (0.93–1.66)
Lymph node involvement    
   Absent    
   Present 1.49 (1.02–2.19) 1.29 (1.02–1.65) 1.22 (0.95–1.58)
Histology    
   Ductal    
   Lobular 1.17 (0.68–2.01) 1.08 (0.76–1.52) 0.99 (0.68–1.43)
   All other 0.68 (0.39–1.18) 1.09 (0.81–1.46) 0.92 (0.66–1.26)
  1. aReference group: age at menarche of more than 14 years, with the category of best prognosis within each tumor characteristic. bOdds ratio estimates adjusted for body mass index at 18 years of age, age at first birth, age at diagnosis, and ever use and type of menopausal hormone therapy (never users, exclusive estrogen therapy, and combined estrogen-progestin therapy). ER, estrogen receptor; PR, progesterone receptor.