title: In vitro evaluation of dose-response curve for paclitaxel in breast cancer.
abstract: BACKGROUND
  The dose-response curve for anticancer agents cannot be evaluated by studying patients directly. To investigate individual differences in the dose-response curve for paclitaxel in breast cancer, we utilized the histoculture drug response assay (HDRA) technique.
  
  
  METHODS
  Twenty specimens obtained from breast cancer patients who underwent surgical resection were used in this study. The inhibition rates of paclitaxel at several concentrations were measured and fitted to a sigmoid dose-response curve, using non-linear least squares analysis with the fitting equation y=A(1-1/(1+exp(B(x-log(C))))), where A denotes maximal response; B, slope factor; and C, ED50.
  
  
  RESULTS
  A dose-response curve was obtained in all tumors. The mean value (+/-SD) of maximum response, slope factor, and ED50 were 90.2+/-5.5%, 9.4+/-4.3, and 36.8+/-17.2 microg/ml, respectively. The slope factor was higher in nuclear grade 3 tumors compared with nuclear grade 1 and 2 tumors.
  
  
  CONCLUSIONS
  An individual dose-response curve for paclitaxel in breast cancer can be obtained using the HDRA technique. Nuclear grade 3 tumors appeared to have more uniform chemosensitivity to paclitaxel compared with nuclear grade 1 and 2 tumors.
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Wakayama Medical University, Wakayama, 641-8509, Japan. yositatu@wakayama-med.ac.jp
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Yoshimasu
authors.forename: Shoji
authors.initials: S
authors.lastname: Oura
authors.forename: Issei
authors.initials: I
authors.lastname: Hirai
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tamaki
authors.forename: Yozo
authors.initials: Y
authors.lastname: Kokawa
authors.forename: Fuminori
authors.initials: F
authors.lastname: Ota
authors.forename: Rie
authors.initials: R
authors.lastname: Nakamura
authors.forename: Yukio
authors.initials: Y
authors.lastname: Shimizu
authors.forename: Mitsumasa
authors.initials: M
authors.lastname: Kawago
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Hirai
authors.forename: Koma
authors.initials: K
authors.lastname: Naito
authors.forename: Megumi
authors.initials: M
authors.lastname: Kiyoi
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Tanino
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Okamura
authors.forename: Tomoko
authors.initials: T
authors.lastname: Furukawa
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000556:secondary / Q000601:surgery; D002288:Adenocarcinoma, Mucinous / Q000188:drug therapy / Q000556:secondary / Q000601:surgery; D002293:Adenocarcinoma, Scirrhous / Q000188:drug therapy / Q000556:secondary / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000972:Antineoplastic Agents, Phytogenic / Q000008:administration & dosage*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D017239:Paclitaxel / Q000008:administration & dosage*; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D017239:Paclitaxel