Table 3.

Hazard Ratios and 95% Confidence Intervals for the Association Between Pancreatic Cancer Risk and Duration of Estrogen-only Therapy Use or Estrogen-Plus-Progestin Therapy Use Compared With Never Use of Hormone Therapy in Postmenopausal Participants in the California Teachers Study, 1995–2009^a

Duration of ET or EPT Use	No. of Cases	Person-years	Multivariable HRb	95% CI
Never use of HT	87	169,758	1	Referent
Current ET use at baseline
Used for <20 years	29	138,356	0.55	0.36, 0.85
Used for ≥20 years	19	43,970	0.55	0.33, 0.91
Current EPT use at baseline
Used for <10 years	50	202,688	0.83	0.56, 1.22
Used for ≥10 years	23	50,645	0.89	0.55, 1.43

Abbreviations: CI, confidence interval; EPT, estrogen-plus-progestin therapy; ET, estrogen-only therapy; HR, hazard ratio; HT, hormone therapy.

^a Analysis of duration of ET use was restricted to never users of HT (referent) and current ET users at baseline. Analysis of duration of EPT use was restricted to never users of HT (referent) and current EPT users at baseline.

^b All models were stratified by age at baseline (in single years) and adjusted for race/ethnicity (non-Hispanic white, black, or other), body mass index, measured as weight in kilograms divided by height in meters squared (<25, 25 to <30, ≥30, or unknown), age at menarche (≤11, 12, 13, or ≥14 years or unknown), total number of full-term pregnancies (nulligravid, gravid nulliparous, 1–2 full-term pregnancies, ≥3 full-term pregnancies, or unknown), smoking status (never, former, current, or unknown), and history of diabetes (no or yes).