Yeah, my recollection about S-1 could be wrong. I think it comes from this study:
Recent progress and limitations of chemotherapy for pancreatic and biliary tract cancers
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3100481/
Here’s what they say about S-1:
Quote:
S-1 is an oral fluoropyrimidine, consisting of tegafur, a prodrug of 5-FU, and two bio-modulators, 5-chloro-2,4-dihydroxypyridine and potassium oxonate, which maintains high serum 5-fluorouracil levels and reduces gastrointestinal toxicity. S-1 has demonstrated efficacy in a variety of solid tumors, especially in Asian patients.
The bolded part seems to suggest that S-1 is more effective in Asian patients. Doesn’t mean that it’s not effective in Western patients. It might be effective, just not to the same extent.
EDIT: Here’s a study that confirmed that the maximum dose of S-1 tolerated by Western patients is lower than the dose tolerated by Japanese patients.
http://jco.ascopubs.org/content/23/28/6957.full