2154
We conclude that the presence of this metabolic defect combined with topical 5-FU ( a drug demonstrating a narrow therapeutic index ) results in the unusual presentation of life - threatening toxicity after treatment with a topical drug .
 life - threatening toxicity, 5-FU
Please list all entity pairs containing a certain relationship in the given options.Output format is "word1, word2; word3, word4". 
Option: adverse effect 
Text: {0} 
Answer:
 life - threatening toxicity, 5-FU