If a large lipoma on the shoulder was confirmed to be a lipoma by mri, should someone go ahead and have surgery just incase it turns cancerous?

I favor surgical rem: Surgical removal is recommended because MRI is not 100% reliable in making the distinction between a benign(Lipoma) and malignant fatty tumor (Liposarcoma).

Confirmation: Lipomas don't turn in to cancer. But they can grow very big and be difficult to remove. MRIs are good but nothing is a good as putting tissue under a microscope. If it has not changed for years you can probably continue to watch it. I it is increasing in size, becoming more hard, or becoming painful those would all be reasons to have it excised. If you want to be sure of Dx. You need a biopsy.