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Table 3 The odds ratios and 95% confidence intervals of reproductive risk factors by BC subtypes

From: The distribution of reproductive risk factors disclosed the heterogeneity of receptor-defined breast cancer subtypes among Tanzanian women

Risk factor

Luminal-A

Luminal-B

HER-2 enriched

Triple-negative

OR (95% CI)

p value

OR (95% CI)

p value

OR (95% CI)

p value

OR (95%CI)

p value

Age at diagnosis

    

< 40 years old

1.00 (Ref)

2.80 (1.46–5.32)

0.002

2.04 (1.89–4.64)

0.089

1.66 (0.88–3.13)

0.119

≥ 40 years old (Ref)

    

Family history of BC

    

Yes

1.00 (Ref)

0.94 (0.43–2.03)

0.940

0.59 (0.18–1.85)

0.364

1.17 (0.55–2.47)

0.353

No (Ref)

    

Menarche

    

Early < 12 years

1.00 (Ref)

1.20 (0.26–5.73)

0.812

1.36 (0.24–1.67)

0.724

0.35 (0.29–1.33)

0.352

Normal 13–14 years

 

1.19 (0.52–1.90)

0.892

0.63 (0.26–1.50)

0.298

0.81 (0.41–1.48)

0.781

Late > 15 years (Ref)

    

Menopausal status

    

Pre-menopause

1.00 (Ref)

0.21 (0.10–0.41)

0.001

0.39 (0.17–0.89)

0.026

0.68 (0.35–1.30)

0.681

Post-menopause (Ref)

    

Age at first full-term pregnancy

    

< 30 years old

1.00 (Ref)

2.71 (1.18–4.17)

0.018

1.85 (0.68–2.51)

0.223

2.28 (1.02–4.07)

0.044

≥ 30 years old (Ref)

    

Parity

    

Nulliparous (Ref)

1.00 (Ref)

0.42 (0.13–1.33)

0.428

0.44 (0.15–1.95)

0.286

0.43 (0.14–1.36)

0.153

≥ 1 Child

    

Breastfeeding

    

Ever(Ref)

1.00 (Ref)

0.46 (0.22–0.95)

0.035

0.69 (0.26–1.81)

0.450

0.41 (0.20–0.85)

0.017

Never

    
  1. The p-values less than 0.05 (typically ≤ 0.05) as being statistically significant and were bolded
  2. The ORs and 95%CIs were found by multinomial logistic regression comparing luminal-A cases as the reference group. All odds ratios (OR) are adjusted age, BMI and family history of BC (yes, no). In all cases, differences were considered significant at p < 0.05
  3. CI confidence interval, OR odds ratio, HER2 human epidermal growth factor receptor 2, Ref reference