Bear in mind that they are making predictions based on general experiences. They can't possibly know exactly what will happen with your mom. They are only guessing.
The fact that there are two tumors in the pelvis may mean that the cancer has "learned" how to travel. Being only in the pelvis, it hasn't traveled very far. It's still possible that the chemo will wipe out the tumors and none will ever appear again. They are saying she will not be cured because there is also a possibility new tumors will appear in other areas of her body even if these shrink to nothing. But they don't know with absolute certainty.
I would also agree you should look into a second opinion. I'm not sure why they are not offering Gamma Knife as an option.
47yo single mom of 4 (24, 21, 18, 16) at Dx
6/13 - RC T4b IIIc 5LNs on PET CEA 5.4
8/13 - Finish chemorad
10/13 - APR/hyst+ovaries/perm colostomy 2/12 nodes+
6/14 - Finish Xelox 6 rds
1/15 - CT clear CEA 0.2
10/15 - CT/MRI clear CEA 0.7
4/16 - CT clear
10/16 - CT/MRI clear CEA 0.6