2794
IMPORTANCE OF THE FIELD : Fluoropyrimidines , in particular 5 - fluorouracil ( 5 - FU ) , have been the mainstay of treatment for several solid tumors , including colorectal , breast and head and neck cancers , for > 40 years .
 Fluoropyrimidines, 5 - fluorouracil, 5 - FU, tumors, colorectal , breast and head and neck cancers
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 Fluoropyrimidines, 5 - fluorouracil, 5 - FU, tumors, colorectal , breast and head and neck cancers