What were the results of the flush??? Stones, cellular poisons, lymphatic debris???
When you uncork the liver the rest of the body opens up and more poisons are released from cells and intersticial spaces. Until the liver filters those out you may get some symptoms. Thus the tumor growth.
After that the tumor should actually shrink and be smaller than before the flush.
Sounds like he's getting pretty close to the end of the cleansing though, so don't stop now. Keep us posted.