title: [Effects of irinotecan and 5-FU combination therapy in gastric cancer--is combination therapy synergic?].
abstract: The response rate of Irinotecan for gastric cancer is reported to be 18. 4%. The rate is improved by combination with 5-FU. However, it remains unclear whether or not the effect of the two drugs is synergy or antagonistic. The purpose of this study is to clarify whether the effect of Irinotecan and 5-FU in gastric cancer is synergy or antagonistic. We performed study using 13 specimens removed surgically and 2 specimen collected from ascites. We performed the Collagen Gel Droplet Embedded Culture Drug Sensitivity Test (CD-DST) with 3 assumptions. In the first assumption, we let 5-FU come in contact with a tumor at a level of 1 mg/mL for 24 hours. The second assumption was SN-38 at a level of 30 mg/mL for 24 hours and the 3rd assumption was SN-38 at a level of 30 mg/mL and 5-FU at a level of 1 mg/mL for 24 hours. If the combination index was more than 1, the combination therapy was judged as synergic; if less than 1, it was considered antagonistic.
  
  
  RESULTS
  The inhibition rate of combination therapy was significantly higher than that of monotherapy. The inhibition rate of combination therapy was significantly correlate with that of monotherapy (Irinotecan; r=0.704, p=0.003, 5-FU; r=0.746, p=0.001). The combination index was antagonistic in only 6 of 15 cases. However, it was synergic in all well-differentiated adenocarcinomas (4/4).
  
  
  CONCLUSIONS
  We conclude that combination therapy is antagonistic in most cases of gastric cancer in vitro. However, it may be synergic in well-differentiated adenocarcinomas.
authors.affiliation: Dept. of Surgery, Nippon Medical School, Chiba-hokusoh Hospital.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yamada
authors.forename: Kiyonori
authors.initials: K
authors.lastname: Furukawa
authors.forename: Kimiyoshi
authors.initials: K
authors.lastname: Yokoi
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Mamada
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Kanazawa
authors.forename: Eiji
authors.initials: E
authors.lastname: Uchida
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage; D000972:Antineoplastic Agents, Phytogenic / Q000008:administration & dosage; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D002166:Camptothecin / Q000008:administration & dosage / Q000031:analogs & derivatives; D004336:Drug Antagonism; D004357:Drug Synergism; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage; D006801:Humans; D066298:In Vitro Techniques; D000077146:Irinotecan; D008297:Male; D008875:Middle Aged; D013274:Stomach Neoplasms / Q000188:drug therapy*
chemical_list: D000964:Antimetabolites, Antineoplastic; D000972:Antineoplastic Agents, Phytogenic; D000077146:Irinotecan; D005472:Fluorouracil; D002166:Camptothecin