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. 2010 Jan 11;171(4):415–425. doi: 10.1093/aje/kwp434

Table 2.

Adjusteda Relative Risks and 95% Confidence Intervals for the Association Between Baseline Status of Menopausal Hormone Therapy Use and Incident Invasive Colon Cancer Among Perimenopausal and Postmenopausal Participants in the California Teachers Study, 1995–2006

Status of HT Use at Baseline (Estrogen, Estrogen + Progestin, or User of Mixed Formulations) Total No. Person-Years No. of Cases Relative Riska 95% Confidence Interval
Ever HT use, at baseline
    Never HT user 13,778 136,333 151 1.00 Referent
    Ever HT user (former and recent HT users) 43,086 434,940 291 0.72 0.58, 0.88
Ever HT use, at baselineb
    Never HT user 13,778 136,333 151 1.00 Referent
    Ever HT user, estrogen therapy only 16,427 162,541 142 0.71 0.56, 0.90
    Ever HT user, estrogen + progestin therapy only 5,324 53,509 32 0.71 0.48, 1.06
    Ever HT user, mixed formulations 21,335 218,891 117 0.72 0.56, 0.93
Former or recent HT use, at baselineb
    Never HT user 13,778 136,333 151 1.00 Referent
    Former HT user 8,653 84,417 98 0.88 0.68, 1.15
    Recent HT user 34,433 350,524 193 0.64 0.51, 0.80
Type of HT used at baselineb
    Never HT user 13,778 136,333 151 1.00 Referent
    Former HT user 8,653 84,417 98 0.88 0.68, 1.14
    Recent estrogen therapy user 15,090 151,523 93 0.59 0.45, 0.77
    Recent estrogen + progestin therapy user 19,343 199,000 100 0.71 0.54, 0.93
Duration of HT use, at baselineb
    Never HT user 13,778 136,333 151 1.00 Referent
    Ever HT user, <5 years’ duration 19,265 196,235 120 0.85 0.66, 1.10
    Ever HT user, 5–15 years’ duration 13,541 137,519 69 0.57 0.42, 0.76
    Ever HT user, >15 years’ duration 8,097 79,596 87 0.73 0.55, 0.96
        Ptrendc 0.19
Duration of HT use, at baseline by former/recent useb
    Never HT user 13,778 136,333 151 1.00 Referent
    Former HT user
        <5 years’ duration 5,788 56,747 64 0.94 0.69, 1.26
        5–15 years’ duration 1,770 17,277 20 0.87 0.55, 1.39
        >15 years’ duration 730 6,854 10 0.91 0.48, 1.73
            Ptrendc 0.97
    Recent HT user
        <5 years’ duration 13,487 139,488 56 0.76 0.54, 1.08
        5–15 years’ duration 11,771 120,242 49 0.49 0.35, 0.68
        >15 years’ duration 7,367 72,743 77 0.69 0.52, 0.92
            Ptrendc 0.60
Duration of HT use, at baseline by formulationb
    Never HT user 13,778 136,333 151 1.00 Referent
    Ever HT user, estrogen therapy only
        <5 years’ duration 6,231 61,785 59 0.89 0.65, 1.21
        5–15 years’ duration 4,489 45,284 28 0.60 0.40, 0.91
        >15 years’ duration 5,203 50,663 53 0.68 0.49, 0.94
            Ptrendc 0.08
Ever HT user, estrogen + progestin therapy only
    <5 years’ duration 2,387 23,959 18 0.91 0.55, 1.53
    5–15 years’ duration 1,873 18,926 7 0.52 0.24, 1.12
    >15 years’ duration 701 6,972 6 0.79 0.35, 1.79
        Ptrendc 0.64
Ever HT user, mixed formulations
    <5 years’ duration 10,647 110,491 43 0.76 0.52, 1.12
    5–15 years’ duration 7,179 73,309 34 0.53 0.36, 0.79
    >15 years’ duration 2,193 21,962 28 0.81 0.53, 1.25
        Ptrendc 0.58
Years since last HT use for former HT users, at baselineb
    Never HT user 13,778 136,333 151 1.00 Referent
    Former HT user, ≤5 years since last use 3,873 38,596 28 0.82 0.54, 1.24
    Former HT user, >5 years since last use 4,747 45,499 70 0.92 0.68, 1.23

Abbreviation: HT, hormone therapy.

a

Adjusted for race (as shown), body mass index (continuous measure), and physical activity (low, intermediate, high) and stratified by age at cohort entry (continuous measure in years).

b

The number of missing is not shown in the table.

c

The trend effect was estimated by using the continuous variable of HT duration (in years) among users.