Phase II study of 2-week TS-1 administration followed by 1-week rest for gastric cancer.
OBJECTIVE
TS-1 monotherapy with 4-week administration followed by 2-week rest is used as the community standard treatment for metastatic gastric cancer in Japan. However, according to a postmarketing survey, the percentage of patients who received three or more courses was only 44.6%; for the reasons of discontinuation due to exacerbation of symptoms or adverse reactions during the first or second course. Therefore, we conducted the phase II study of 2-weeks administration with TS-1 followed by a 1-week rest against metastatic gastric cancer, aiming for mitigation of adverse reactions without reduction of antitumor effect.


METHODS
Thirty-five patients were enrolled between 2001 and 2003 at nine institutes in Japan. One cycle of TS-1 treatment whose dosage was 80 mg/m2/day consisted of administration for 2 weeks followed by a 1-week rest. The primary endpoint was overall response rate and the secondary endpoints were safety and feasibility.


RESULTS
There were 6 PRs, 13 NCs, 11 PDs, and 5 patients were not evaluable (NE), yielding a response rate of 17%. The median survival time of all patients was 290 days. Severe adverse Grade 3 or 4 reactions were observed in 8 (23%) patients. The rate of patients who received six or more courses was 43%. The cumulative rate of the relative total administration days was 93%.


CONCLUSIONS
We concluded that the schedule of TS-1 administration for 2 weeks followed by a 1-week rest might not be superior to the conventional schedule (4 weeks on and 2 weeks off) with regard to the antitumor effect, adverse reactions and prolonged medication, although it was acceptable from the point of view of survival.
Imamura
Hiroshi
H
Department of Surgery, Sakai Municipal Hospital, Osaka, Japan. imamura-h@city.sakai.osaka.jp
Furukawa
Hiroshi
H
Kishimoto
Tomono
T
Nakae
Siro
S
Inoue
Kentaro
K
Tsukahara
Yasuo
Y
Imano
Motohiro
M
Yamazaki
Keiji
K
Okano
Shinji
S
Morimoto
Takashi
T
Sugihara
Seiichi
S
Shimokawa
Toshio
T
D000230:Adenocarcinoma / Q000188:drug therapy* / Q000401:mortality; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D017640:Silicates / Q000008:administration & dosage*; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000401:mortality; D016019:Survival Analysis; D014025:Titanium / Q000008:administration & dosage*; D016896:Treatment Outcome
D000970:Antineoplastic Agents; D017640:Silicates; C103828:titanium silicide; D014025:Titanium