The best replacement for 5-fu is xeloda.

The best alternatives to 5-fu are rated as following:
★★★★★  xeloda
★★★★★  gemcitabine
★  capecitabine

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Speaking about 5-fu, one probably shouldn't forget about leucovorin.

Other search terms related to 5-fu and their ratings are:
★★★★★ leucovorin
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