Journal of Clinical Oncology, Vol 12, 1630-1638, Copyright © 1994 by American Society of Clinical Oncology
Tamoxifen versus high-dose oral medroxyprogesterone acetate as initial endocrine therapy for patients with metastatic breast cancer: a Piedmont Oncology Association study
HB Muss, LD Case, JN Atkins, JD Bearden 3rd, MR Cooper, JM Cruz, DV Jackson Jr, MA O'Rourke, MD Pavy and BL Powell
Comprehensive Cancer Center, Wake Forest University, Winston-Salem, NC 27157-1082.
PURPOSE: To determine in a prospective randomized trial whether high- dose
orally administered medroxy-progesterone acetate (MPA) was superior to
tamoxifen in patients with recurrent or metastatic breast cancer who had
received no prior endocrine therapy in either the adjuvant or advanced
setting. PATIENTS AND METHODS: Patients initially received either tamoxifen
20 mg/d orally or MPA 1 g/d orally. At the time of disease progression,
patients were crossed over to the other regimen. Eligibility required
patients to be age > or = 18 years, performance status 0 to 3, and
estrogen receptor (ER)- or progesterone receptor (PR)-positive or unknown.
RESULTS: One hundred eighty-two eligible patients were entered and 166 were
assessable for response. Complete plus partial response rates for tamoxifen
and MPA were 17% and 34%, respectively (P = .01). Patients with bone
metastases had a significantly higher partial response rate with MPA
compared with tamoxifen (33% v 13%). Median time to treatment failure was
5.5 months for tamoxifen and 6.3 months for MPA (P = .48). The median
survival duration was 24 months for tamoxifen and 33 months for MPA (P =
.09). Multivariate analysis showed that treatment significantly influenced
response rate, but not time to treatment failure or survival. After
treatment failure following MPA, six of 42 patients (14%) treated with
tamoxifen responded, compared with six of 49 (12%) treated with MPA
following tamoxifen. Both agents were associated with minimal toxicity, but
35% of patients on MPA gained more than 20 lb as opposed to only 2% on
tamoxifen. CONCLUSION: In this trial, initial treatment with MPA of
endocrine-naive metastatic breast cancer patients was associated with a
significantly higher response rate but not with improvement in time to
treatment failure or survival, when compared with initial treatment with
tamoxifen. Further randomized trials in patients with bone metastases are
warranted to determine if high-dose progestin therapy is superior to
tamoxifen in these patients.