1911
Median progression - free survivals ( PFSs ) were 2 . 6 ( stratum 1 ) and 2 . 7 months ( stratum 2 ) .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 None