3BEP vs 4EP

[IowaBrian]

http://www.medscape.com/viewarticle/417748_2

here is one study I know if you do a search on this forum it has been talked about I believe in the USA they like to do the 3 BEP but if you have lung issues or have a problem with the B then they will switch to the 4 EP.
Brian

[mjc8185]

Are there any discussions available regarding the differences between 3BEP vs 4EP? I'm told MD Anderson does 4EP vs 3BEP. I'm assuming this is at least partly due to the fact that Houston air quality is not the greatest and therefore BEP may be riskier (?).