Avastin followp

Has anyone heard of taking Avastin as a follow-up to treatment when there is no evidence of disease?  My onc has recommended this to me and she said there are not any studies that she knows of about this because the success of my chemo was so great.    There is a small study of people who still show signs.  You see I am Triple Neg and I have mets to the lymph nodes behind my breast bone.  After the cancer came back in the nodes I was given 4 rounds of A/C + Avastin and my last PET CT was all clear.  I was told that they did not expect this outcome and that it was truely unbelievable that it is gone (and it will most certainly come back).  I credit God for healing me, I know he answers prayers but he also wouldn't want me to be stupid and not do anything I can to keep the cancer from coming back.  I think I will agree to this follow-up treatment but wanted to know your thoughts.  Thanks!