Avastin and fistula


My mom is diagnosed with recurrence in pelvis - few nodes lit up in pet scan in right internal iliac region.
One of the Oncologists(whom we went for second opinion) said risk of avastin causing fistula and infection is high if the tumour is in radiated area.
Is there any data for this? Have any of you heard/experienced the same?

Infact she had first round of folfiri + avastin last week. 
She fell down while using restroom just after couple of hrs after infusion of avastin.
She said she couldnt remember what happened perhaps she lost consciousness for a min or so. At that time her BP was high.
Our onc said he doesn't doubt on avastin but sent for neurology opinion and neurologist said it looks like or could be seizure.
And prescribed some medication.

NOw want to weigh all the side effects and benefit of using avastin.

As usual thanks for sharing any info you would know on this.

Son of mom,
May2012 - LAR for rectal tumour
June - Nov 2012 - Radiation + chemo(FOLFOX)