Comparison of two-year and five-year tamoxifen use in Japanese post-menopausal women.
OBJECTIVE
Large multicenter, randomized trials have revealed the advantages of using tamoxifen for 5 years vs 2 years in breast cancer patients. The aim of this report is to confirm the optimal duration of tamoxifen administration in a study of Japanese breast cancer patients.


METHODS
Japanese post-menopausal estrogen receptor-positive breast cancer patients treated with mastectomy were randomly assigned to either a 5-year or 2-year course of tamoxifen. The primary endpoint was disease-free survival, with secondary endpoints of overall survival and a reduction in the development of metachronous contra-lateral breast cancer.


RESULTS
A total of 256 breast cancer patients were randomized to a 5-year or 2-year tamoxifen administration group. After a median follow-up time of 81 months, there were no significant differences seen in terms of disease-free or overall survival (p=0.65 and 0.56, respectively). Furthermore, the impact of the 5-year use of tamoxifen on the development of contra-lateral breast cancer did not reach statistical significance (p=0.0511). However, 5-year tamoxifen use was closely associated with gynaecological complications (p=0.0081).


CONCLUSIONS
We could not show a beneficial effect of using tamoxifen for 5 years over 2 years in Japanese estrogen receptor-positive patients. This is likely due to the small number of patients enrolled in our study; however, racial disparity may influence this result. A reevaluation is necessary to study the advantages of the 5-year use of tamoxifen in the Japanese racial subgroup.
Tada
K
K
Department of Surgery, Cancer Institute Hospital, 1-37-1 Kami-ikebukuro, Toshima-ku, Tokyo 170-8455, Japan. ktada@jfcr.or.jp
Yoshimoto
M
M
Nishimura
S
S
Takahashi
K
K
Makita
M
M
Iwase
T
T
Takahashi
S
S
Ito
Y
Y
Hatake
K
K
Ueno
M
M
Nakagawa
K
K
Kasumi
F
F
D000328:Adult; D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000009:adverse effects / Q000627:therapeutic use*; D044466:Asian People / Q000208:ethnology; D001943:Breast Neoplasms / Q000188:drug therapy*; D017024:Chemotherapy, Adjuvant; D018572:Disease-Free Survival; D004965:Estrogen Antagonists / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D005831:Genital Diseases, Female / Q000139:chemically induced; D006801:Humans; D007564:Japan / Q000208:ethnology; D008207:Lymphatic Metastasis / Q000473:pathology; D008408:Mastectomy; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000517:prevention & control; D017698:Postmenopause; D011960:Receptors, Estrogen / Q000032:analysis; D015996:Survival Rate; D013629:Tamoxifen / Q000009:adverse effects / Q000627:therapeutic use*
D018931:Antineoplastic Agents, Hormonal; D004965:Estrogen Antagonists; D011960:Receptors, Estrogen; D013629:Tamoxifen