Incidence of breast cancer in a 22-year study of women receiving estrogen-progestin replacement therapy.
OBJECTIVE
To review the incidence of breast cancer in a continuous 22-year study of conjugated estrogen-medroxyprogesterone acetate hormone replacement therapy.


METHODS
Eighty-four pairs of continuously hospitalized postmenopausal women who were matched for age, smoking history, and medical diagnosis were treated with estrogen-progestin hormone replacement therapy or placebo in a prospective and double-blind manner for 10 years. In the subsequent 12 years, the women were offered the choice of starting, stopping, or continuing hormone replacement therapy.


RESULTS
After the initial 10 years, the incidence of breast cancer in the placebo group was 4.8%, whereas no cancers were found in the hormone replacement therapy group (P = .12). After an additional 12 years of follow-up, the overall incidence of breast cancer in the women who had never taken hormone replacement therapy was 11.5%, whereas no breast cancers had developed in the women who had ever taken hormone replacement therapy (P < .01).


CONCLUSIONS
These data suggest that the 22-year administration of estrogen-progestin hormone replacement therapy did not increase the incidence of breast cancer in a small group of continuously hospitalized postmenopausal women.
Nachtigall
M J
MJ
Department of Obstetrics and Gynecology, New York University-Bellevue Medical Center, New York.
Smilen
S W
SW
Nachtigall
R D
RD
Nachtigall
R H
RH
Nachtigall
L E
LE
D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000139:chemically induced / Q000453:epidemiology*; D004311:Double-Blind Method; D015914:Estrogen Replacement Therapy; D004966:Estrogens, Conjugated (USP) / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D015993:Life Tables; D016555:Matched-Pair Analysis; D017258:Medroxyprogesterone Acetate / Q000009:adverse effects / Q000627:therapeutic use*; D008875:Middle Aged; D011446:Prospective Studies; D013997:Time Factors
D004966:Estrogens, Conjugated (USP); D017258:Medroxyprogesterone Acetate