Association between prediagnostic leukocyte telomere length and breast cancer risk: the Singapore Chinese Health Study

Table 4 Associations between relative telomere length and risk of breast cancer stratified by age and body mass index, Singapore Chinese Health Study

Telomere length in quartile by stratification variable	Cases	Person-years	Adjusted HR¹ (95% CI)	P interaction
Age (< 60 years)
Q1 (shortest)	28	12,985	1.00 (reference)	0.30
Q2	41	17,826	1.05 (0.65, 1.70)
Q3	64	20,853	1.38 (0.88, 2.15)
Q4 (longest)	86	25,899	1.52 (0.99, 2.33)
P_trend			0.017
Age (≥ 60 years)
Q1 (shortest)	56	30,050	1.00 (reference)
Q2	65	26,267	1.32 (0.92, 1.89)
Q3	56	23,459	1.26 (0.87, 1.82)
Q4 (longest)	46	19,275	1.27 (0.86, 1.88)
P_trend			0.25
Body mass index (< 23.0 kg/m²)
Q1 (shortest)	38	20,617	1.00 (reference)	0.45
Q2	44	21,321	1.12 (0.72, 1.73)
Q3	46	21,377	1.14 (0.74, 1.76)
Q4 (longest)	55	22,407	1.31 (0.86, 2.01)
P_trend			0.21
Body mass index (≥ 23.0 kg/m²)
Q1 (shortest)	46	22,417	1.00 (reference)
Q2	62	22,772	1.32 (0.90, 1.94)
Q3	74	22,935	1.51 (1.04, 2.19)
Q4 (longest)	77	22,766	1.59 (1.09, 2.32)
P_trend			0.013

CI confidence intervals, HR hazard ratio
¹Hazard ratio derived from Cox proportional hazard regression model adjusted for age at sample collection, dialect group, level of education, BMI, age when period became regular, age at first live birth, number of live births, age at menopause, use of hormone therapy, use of oral contraceptives, family history of breast cancer, smoking status, alcohol consumption, weekly vigorous work or strenuous sports, and number of hours of sleep

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