J Cancer 2015; 6(5):464-469. doi:10.7150/jca.11189

Research Paper

Risk Factors for Discontinuation of S-1 Adjuvant Chemotherapy for Gastric Cancer

Hitoshi Kawazoe1,*, Maya Shimasaki2,*, Masaki Ueno1, Satomi Sumikawa1, Shingo Takatori2, Hiroyuki Namba2, Motohira Yoshida3, Koichi Sato3, Yoh Kojima3, Yuji Watanabe3, Toshihide Moriguchi1, Akihiro Tanaka1✉, Hiroaki Araki1

1. Division of Pharmacy, Ehime University Hospital, Shitsukawa, Toon, Ehime 791-0295, Japan;
2. Department of Clinical Pharmacy, College of Pharmaceutical Sciences, Matsuyama University, Bunkyou, Matsuyama, Ehime 790-8578, Japan;
3. Division of Gastrointestinal Surgery and Surgical Oncology, Department of Surgery, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime 791-0295, Japan.
* Hitoshi Kawazoe and Maya Shimasaki equally contributed to this work.

Abstract

Purpose: The aim of this study was to clarify the risk factors for discontinuing tegafur/gimeracil/oteracil potassium (S-1) adjuvant chemotherapy following gastrectomy in patients with gastric cancer.

Methods: We retrospectively investigated patients with curatively-resected gastric cancer who received S-1 adjuvant chemotherapy. S-1 was administered orally at 80-120 mg/day, depending on body surface area, on days 1-28 every 6 weeks for 1 year. The dose and treatment schedule were modified at the clinicians' discretion, according to toxicity.

Results: Seventy-one patients were included in the study, 26 of whom discontinued S-1 therapy. The relapse-free survival rates in the S-1-completed and S-1-discontinuation groups at 5 years post-surgery were 88.1% and 55.8%, respectively. The overall survival rates in the S-1-completed and S-1-discontinuation groups at 5 years post-surgery were 89.4% and 59.8%, respectively. The hazard ratios for relapse and death were significantly lower in the S-1-completed group compared with those in the S-1-discontinuation group (0.18; p<0.001 and 0.19; p=0.002, respectively). Multivariate logistic regression analysis revealed that S-1 discontinuation was significantly associated with an initial overdose of S-1, having stage I cancer, creatinine clearance <66 mL/min, and a side effect of nausea.

Conclusions: These results suggest that assessing renal function to avoid initial overdose of S-1, together with the early management of side effects, may support the continuation of S-1 adjuvant chemotherapy in patients with gastric cancer.

Keywords: Adjuvant chemotherapy, Tegafur/gimeracil/oteracil potassium (S-1), Gastric cancer, Discontinuation, Risk factor.

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How to cite this article:
Kawazoe H, Shimasaki M, Ueno M, Sumikawa S, Takatori S, Namba H, Yoshida M, Sato K, Kojima Y, Watanabe Y, Moriguchi T, Tanaka A, Araki H. Risk Factors for Discontinuation of S-1 Adjuvant Chemotherapy for Gastric Cancer. J Cancer 2015; 6(5):464-469. doi:10.7150/jca.11189. Available from http://www.jcancer.org/v06p0464.htm