Can I refer to my previous CASE expression? I know the code is wrong but I want to do something like this:

SELECT
Distinct(trafficSource.campaign) AS Campaign,

Case 
  When (SUBSTR(trafficSource.campaign,10,4)) = 'news' then  'eNEWS'
  When (SUBSTR(trafficSource.campaign,23,4)) = 'news' then  'eNEWS'
  Else Null
End as **eNEWS_Flag**,

Case
  When **eNEWS_Flag** = 'eNEWS' then (SUBSTR(trafficSource.campaign,21,2)) Lang_Flag,

From Blah Blah 

WHERE eNEWS_Flag is NOT NULL