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

Table 3 Associations between relative telomere length and risk of breast cancer, the Singapore Chinese Health Study

Telomere length in quartile^§	Cases	Person-years	HR¹ (95% CI)	HR² (95% CI)
Q1 (0.73–0.85)	84	43,035	1.00 (ref)	1.00 (ref)
Q2 (0.92–0.99)	106	44,093	1.21 (0.91, 1.62)	1.22 (0.91, 1.62)
Q3 (1.06–1.13)	120	44,312	1.35 (1.02, 1.79)	1.35 (1.01, 1.78)
Q4 (1.23–1.40)	132	45,174	1.45 (1.09, 1.91)	1.47 (1.11, 1.94)
P _trend			0.008	0.006

CI confidence intervals, HR hazard ratio
^§Numbers inside the parentheses are interquartile ranges
¹Hazard ratios and P values were derived from the Cox proportional hazard regression model that included age at blood collection and dialect group (Hokkien or Cantonese)
²Hazard ratio and P values were derived from the Cox proportional hazard regression model that also included level of education (no formal education, primary school, or secondary school and above), BMI (< 18.5, 18.5 to < 23, 23 to < 27.5, 25.5+ kg/m²), age when period became regular, age at first live birth (< 10, 21–25, 26–30, or ≥ 31 years), number of live births (0, 1–2, 3–4, or ≥ 5), age at menopause (≤ 49, 50–54, or ≥ 55 years), use of hormone therapy (never, ever, or current), use of oral contraceptives (no or yes), family history of breast cancer (no or yes), smoking status (never, former, or current smoker), alcohol consumption (non-drinker, < 7 or ≥ 7 drinks per week), weekly vigorous work or strenuous sports (no or yes), and number of hours of sleep

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