Table 3.

Cumulative average caffeine intake and risk of endometrial cancer in the NHS cohort

Caffeine intake, RR (95% CI)
Quintile 1Quintile 2Quintile 3Quintile 4Quintile 5Ptrend
Median intake (mg/d)64.0177.6304.6410.0666.5
Person-years226,482249,283269,561265,467272,451
No. of cases134144151140103
Age-adjusted1.000.93 (0.74–1.18)0.88 (0.70–1.12)0.85 (0.67–1.08)0.62 (0.48–0.80)0.002
Multivariable-adjusteda1.000.98 (0.77–1.24)0.98 (0.77–1.24)0.96 (0.75–1.22)0.72 (0.55–0.95)0.02
Multivariable-adjustedb1.000.99 (0.78–1.27)0.96 (0.75–1.23)0.97 (0.76–1.24)0.69 (0.52–0.91)0.01
  • aAdjusted for age (mo, continuous), BMI (kg/m2, continuous), age at menopause [pre-/unknown menopause, <45 y, 45–46 y, 47–48 (ref), 49–50 y, 51–52 y, and ≥53 y], age at menarche [<12 y, 12 y (ref), and >12 y], parity and age at last birth [nulliparous (ref), parity 1–2 and age at last birth <30 y, parity 1–2 and age at last birth parity ≥30 y, parity 3–4 and age at last birth <30 y, parity 3–4 and age at last birth ≥30 y, parity ≥5 and age at last birth <30 y, and parity ≥5 and age at last birth ≥30 y], duration of oral contraceptive use [never (ref), <3 y, past 3–5 y, and past >5 y], postmenopausal hormone use [premenopausal, postmenopausal never (ref), past PMH, current PMH estrogen only, current PMH estrogen with progesterone], pack-years of smoking [never (ref), >0–10 pack-years, >10–20 pack-years, >20–30 pack-years, >30–40 pack-years, >40 pack-years], alcohol intake [0 (ref), 0.1–4.9 g/d, 5.0–14.9 g/d, >15.0g/d], and total energy intake (kcal/d, continuous).

  • bExcluded cases that occurred during the first 2-year follow-up period (n = 33) to minimize the possibility that preclinical disease influenced dietary assessment.