Hello,
My dad was recently diagnosed with a GI NET. We live in the US . The primary tumor is 6cm in diameter and in/near/on his pancreas, and is also inoperable due to being all up in some important arteries. Mesinteric artery sounds familiar. His tumor was causing a big problem because it was oozing blood into the GI tract, resulting in life-threatening anemia/low iron (which caused symptoms that led to his diagnosis).

He had a 2-week course of radiation therapy targeting the tumor, and is now on a monthly lanreotide injection. The radiation won't likely shrink the tumor, but it will help keep it asleep. I think it was called for to help stop the internal bleeding, too. He just had surgery to have a stent put in a vein that the tumor was pushing on. That's all the treatment he will have for the foreseeable future.
His tumor has spread to the lymph system, liver, maybe a few other places. But it's slow growing and non-functional.

Sounds like chemotherapy is something that could be considered in the distance future if needed, but it's not part of the standard of care for the point he's at. My dad did a conference consult at the Mayo Clinic where there are some top NET experts, and they agreed with everything his oncologist had been doing to date (but also recommended getting the stent placed).

What I have gathered is that lanreotide is the front line treatment for inoperable GI NETs. It feels anticlimactic, but I'm grateful because as treatments go it's pretty low drama, low time commitment, and no side effects for him.

I don't know if there's any stent equivalent for the bowel, to stop your tumor from pushing on it. Sorry to hear about those symptoms, that sounds rough.

Good luck! Sounds like you have a good doctor. I hope there's something that can be done for your various symptoms.