Efficacy of weekly paclitaxel in patients with docetaxel-resistant metastatic breast cancer.
BACKGROUND
Partial cross-resistance to paclitaxel and docetaxel has been demonstrated in pre-clinical studies.


METHODS
We retrospectively evaluated the efficacy of weekly paclitaxel 80 mg/m(2) in 82 patients with docetaxel-resisitant metastatic breast cancer. Docetaxel resistance was classified into primary resistance, defined as progressive disease while receiving docetaxel, and secondary resistance, defined as progression after achievement of a documented clinical response to docetaxel. Secondary resistance was subclassified according to the interval between the final infusion of docetaxel and the start of weekly paclitaxel into: (1) short interval, < or =120 days, and (2) long interval, >120 days.


RESULTS
The response rate of the 82 patients was 19.5% (95% confidence interval, 10.8-27.9%). The response rate according to the docetaxel resistance category was: primary resistance (n = 24), 8.3%; secondary resistance (n = 58), 24.1% (short interval [n = 39], 17.9%, and long interval, [n = 19], 36.8%). The differences in response rates among the three categories were statistically significant (p = 0.0247, Cochran-Mantel-Haenszel test). The interval between from the final docetaxel infusion and disease progression were predictors for response of weekly paclitaxel.


CONCLUSIONS
Weekly paclitaxel is modestly effective and safe in docetaxel-resistant metastatic breast cancer patients. However, weekly paclitaxel should not be recommended for primary resistance patients with docetaxel.
Yonemori
Kan
K
Breast and Medical Oncology Division, Department of Medical Oncology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan.
Katsumata
Noriyuki
N
Uno
Hajime
H
Matsumoto
Koji
K
Kouno
Tsutomu
T
Tokunaga
Shinya
S
Yamanaka
Yasuhiro
Y
Shimizu
Chikako
C
Ando
Masashi
M
Takeuchi
Masahiro
M
Fujiwara
Yasuhiro
Y
D000972:Antineoplastic Agents, Phytogenic / Q000627:therapeutic use*; D001859:Bone Neoplasms / Q000188:drug therapy / Q000556:secondary; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D018450:Disease Progression; D000077143:Docetaxel; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy / Q000556:secondary; D008175:Lung Neoplasms / Q000188:drug therapy / Q000556:secondary; D008207:Lymphatic Metastasis / Q000473:pathology; D008875:Middle Aged; D017239:Paclitaxel / Q000627:therapeutic use*; D012189:Retrospective Studies; D016879:Salvage Therapy; D043823:Taxoids / Q000627:therapeutic use*; D016896:Treatment Outcome
D000972:Antineoplastic Agents, Phytogenic; D043823:Taxoids; D000077143:Docetaxel; D017239:Paclitaxel