RT Journal
A1 Cobleigh MA, Norlock FE, Oleske DM, Starr A
T1 HOrmone replacement therapy
and high s phase in breast cancer
JF JAMA
JO JAMA
YR 1999
FD April 28
VO 281
IS 16
SP 1528
OP 1530
DO 10.1001/jama.281.16.1528
UL http://dx.doi.org/10.1001/jama.281.16.1528
AB Context 
                  Prolonged postmenopausal hormone replacement therapy
(HRT) is associated with increased incidence of breast cancer and,
paradoxically, reduced breast cancer mortality. The biological
rationale for this discrepancy has not been explored.Objective 
                  To compare the prognostic characteristics of cancers
arising in women who have used HRT with those in women who never have
used HRT.Design 
                  Prospective cohort study from December 1989 to November
1996.Setting 
                  Teaching hospital in a large midwestern metropolitan area.Patients 
                  Cohort of 331 postmenopausal women who presented
consecutively with 349 invasive breast cancers.Main Outcome Measures 
                  Estrogen receptor (ER) status (ER positive
vs ER negative) and S phase (low vs high) for current HRT users vs
never users.Results 
                  The frequency of high S-phase fraction among cancers in
women who were using HRT was markedly increased compared with that in
women who had never used HRT (adjusted odds ratio [OR], 2.82; 95%
confidence interval [CI], 1.04-7.66). However, the greater frequency
of high S-phase fraction was limited to women with ER-positive cancers
(for HRT users vs never users, OR, 5.25; 95% CI, 1.36-20.28; for
ER-negative cancers in HRT users vs never users, OR, 1.08; 95% CI,
0.20-5.86).Conclusions 
                  Use of HRT appears to stimulate growth of ER-positive
but not ER-negative breast cancer as measured by S-phase fraction.
The prognostic significance of high S-phase fraction in current HRT
users who have ER-positive tumors is unknown.