unusual line slav defense [FEN ""] 

1.d4 d5 2.c4 c6 3.Nc3 Nf6 4.Nf3


Here we reach slav defense main line and theory goes with 4...e6

As a way to avoid theory as black I used to play in blitz 4...g6, goes with bishop fianchetto and castle.

As white I'm a d4 player and although not many people deviate 4...e6 with 4...g6 this could happen.

Searching in professional games I didn't see many games with 4...g6.

My question is: How white proceed after 4...g6? (there must be a reason why professionals rare play this move)
According to this database: 

The next move for white will be:


5.e3 with 40% of win, 46% of draw and 14% of lose. (3538 games were played like that)
5.cxd5 with 48.5% of win, 41.5% of draw. (344 games were played like that)


Example for a game which start like this:

[Event "1st Rottal Open 2017"]
[Site "Pfarrkirchen GER"]
[Round "6.1"]
[Date "2017.4.17"]
[White "Haba, Petr"]
[Black "Riediger, Martin"]
[Result "1/2-1/2"]

[FEN ""]    
1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.Nc3 g6 5.cxd5 cxd5 6.Bf4 a6 7.h3 Bg7 8.e3 Nc6 9.Be2 O-O 10.O-O Bf5 11.Rc1 Ne4 12.Na4 Bd7 13.Qb3 b5 14.Nc5 Nxc5 15.Rxc5 e6 16.Bd6 Re8 17.Ne5 Nxe5 18.dxe5 f6 19.Bc7 Qe7 20.Bd6 Qd8 21.Bc7 Qe7 22.Bd6 1/2-1/2