Alternate-day treatment with S-1 in patients with gastric cancer: a retrospective study of strategies for reducing toxicity.
BACKGROUND
In patients with adverse events of S-1, the dose is generally reduced or the treatment cycle is shortened. Whether the therapeutic effectiveness of modified regimens is similar to that of the standard dosage remains unclear.


METHODS
We retrospectively studied patients with gastric cancer who received S-1 on alternate days.


RESULTS
A total of 266 patients received S-1 on alternate days. In 116 patients, S-1 was initially given at the standard dosage but was switched to alternate-day treatment because of toxicity within 28 days on average. The other 150 patients initially received alternate-day treatment because of poor general condition. In the adjuvant chemotherapy group (n = 96), the 3-year survival rate was 88% in patients with stage II, 73% in stage IIIA, and 67% in stage IIIB who underwent D2 lymph-node dissection. In the palliative surgery group (n = 96), the response rate was 13%, with a median survival time (MST) of 624 days. In patients with unresectable/recurrent disease (n = 74), the response rate was 25%, with an MST of 338 days. Among the 116 patients who initially received treatment on consecutive days, 100% had grade 1, 53% had grade 2, and 5.2% had grade 3 adverse events. When S-1 was switched to alternate-day treatment, toxicity decreased in all patients. In the 266 patients who received alternate-day treatment, 8% had grade 1, 6% had grade 2, and 0% had grade 3 adverse events.


CONCLUSIONS
Alternate-day treatment with S-1 may have milder adverse events without compromising therapeutic effectiveness.
Sakuma
Kazuya
K
Department of Surgery, Jichi Medical University, 3311-1 Shimotsuke, Tochigi, 329-0498, Japan.
Hosoya
Yoshinori
Y
Arai
Wataru
W
Haruta
Hidenori
H
Ui
Takashi
T
Kurashina
Kentaro
K
Saito
Shin
S
Hirashima
Yuki
Y
Yokoyama
Taku
T
Zuiki
Toru
T
Hyodo
Mananobu
M
Nagai
Hideo
H
Yasuda
Yoshikazu
Y
Shirasaka
Tetsuhiko
T
D000328:Adult; D000368:Aged; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage* / Q000009:adverse effects; D017024:Chemotherapy, Adjuvant; D018572:Disease-Free Survival; D004334:Drug Administration Schedule; D004338:Drug Combinations; D005260:Female; D005743:Gastrectomy; D006801:Humans; D053208:Kaplan-Meier Estimate; D008197:Lymph Node Excision; D008297:Male; D008875:Middle Aged; D010094:Oxonic Acid / Q000008:administration & dosage* / Q000009:adverse effects; D010166:Palliative Care; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000401:mortality / Q000601:surgery; D005641:Tegafur / Q000008:administration & dosage* / Q000009:adverse effects; D013997:Time Factors; D016896:Treatment Outcome
D000964:Antimetabolites, Antineoplastic; D004338:Drug Combinations; C079198:S 1 (combination); D005641:Tegafur; D010094:Oxonic Acid