Inclusion Criteria:

1. Recurrent gastric cancer histologically confirmed as being adenocarcinoma

2. Age of 20 to 74 years with either gender

3. ECOG Performance Status of 0 to 2

4. Lesions confirmed on imaging within 28 days before registration (not required
measurable lesions as defined in RECIST version 1.1)

5. Post-gastrectomy adjuvant chemotherapy including S-1 for at least 12 weeks including
interruption period

6. Less than 6 months treatment-free interval from completion of adjuvant therapy

7. Treatment-naïve recurrent gastric cancer

8. Life expectancy of at least 3 months after registration

9. Written informed consent

10. Adequate major organ functions within 14 days before registration

Exclusion Criteria:

1. Positive HER2 status

2. Previous treatment with platinum agents

3. Previous history of serious hypersensitivity to fluoropyrimidines or platinum agents

4. Previous history of adverse reactions suggestive of dihydropyrimidine dehydrogenase
(DPD) deficiency

5. More than one cancer at the same time or more than one cancer at different times
separated by a 5-year disease-free interval. However, multiple active cancers do not
include carcinoma in situ or skin cancer which is determined to have been cured as a
result of treatment.

6. Obvious infection or inflammation (pyrexia ≥ 38.0˚C)

7. Active hepatitis

8. Heart disease that is serious or requires hospitalization, or history of such disease
within past year

9. Concurrent illness that is serious or requires hospitalization (intestinal paralysis,
intestinal obstruction, interstitial pneumonia or pulmonary fibrosis, poorly
controlled diabetes mellitus, renal failure, liver disorders, or hepatic cirrhosis)

10. Being treated or in need of treatment with phenytoin or warfarin potassium

11. Chronic diarrhea (watery stool or ≥ 4 times/day)

12. Active gastrointestinal hemorrhage

13. Body cavity fluids requiring drainage or other treatment

14. Clinical suspicion or previous history of metastases to brain or meninges

15. Women who are pregnant, breastfeeding, or potentially (hoping to become) pregnant

16. Unwillingness to practice contraception

17. Poor oral intake

18. Psychiatric disorders which are being or may need to be treated with psychotropics

19. Otherwise determined by investigators or site principal investigators to be
unsuitable for participation in study