Toremifene and tamoxifen are equally effective for early-stage breast cancer: first results of International Breast Cancer Study Group Trials 12-93 and 14-93.
BACKGROUND
Toremifene is a chlorinated derivative of tamoxifen, developed to improve its risk-benefit profile. The International Breast Cancer Study Group (IBCSG) conducted two complementary randomized trials for peri- and postmenopausal patients with node-positive breast cancer to compare toremifene versus tamoxifen as the endocrine agent and simultaneously investigate a chemotherapy-oriented question. This is the first report of the endocrine comparison after a median follow-up of 5.5 years.


METHODS
1035 patients were available for analysis: 75% had estrogen receptor (ER)-positive primary tumors, the median number of involved axillary lymph nodes was three and 81% received prior adjuvant chemotherapy.


RESULTS
Toremifene and tamoxifen yielded similar disease-free (DFS) and overall survival (OS): 5-year DFS rates of 72% and 69%, respectively [risk ratio (RR)=0.95; 95% confidence interval (CI)=0.76-1.18]; 5-year OS rates of 85% and 81%, respectively (RR = 1.03; 95% CI = 0.78-1.36). Similar outcomes were observed in the ER-positive cohort. Toxicities were similar in the two treatment groups with very few women (<1%) experiencing severe thromboembolic or cerebrovascular complications. Quality of life results were also similar. Nine patients developed early stage endometrial cancer (toremifene, six; tamoxifen, three).


CONCLUSIONS
Toremifene is a valid and safe alternative to tamoxifen in postmenopausal women with endocrine-responsive breast cancer.
Instituto Oncologico Svizzera Italiana IOSI, Ospedale Beata Vergine, Mendrisio, Switzerland. opagani@siak.ch
Pagani
Olivia
O
Gelber
Shari
S
Price
Karen
K
Zahrieh
David
D
Gelber
Richard
R
Simoncini
Edda
E
Castiglione-Gertsch
Monica
M
Coates
Alan S
AS
Goldhirsch
Aron
A
D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000009:adverse effects / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008875:Middle Aged; D009367:Neoplasm Staging; D011788:Quality of Life; D011960:Receptors, Estrogen / Q000032:analysis; D013629:Tamoxifen / Q000009:adverse effects / Q000627:therapeutic use*; D017312:Toremifene / Q000009:adverse effects / Q000627:therapeutic use*; D016896:Treatment Outcome
D018931:Antineoplastic Agents, Hormonal; D011960:Receptors, Estrogen; D013629:Tamoxifen; D017312:Toremifene