Sigmoid Colectomy

I am 47 years old and the doctor scheduled me for Colonoscopy November 9th the results were a cancerous tumor size 3-4 cm in the colon He scheduled a appointment with the surgeon and he scheduled a CT Scan and that was normal and the CEA Labs were normal. I was so happy to hear about that. But he said he will not know how much to cut my colon until he goes in during surgery. This is a terrible thing and I am trusting God that I will not have to start chemo or radiation. I'm so scared of the surgery can someone please let me know about this. The surgeon explained that I may have to wear a colostomy bag but I'm not claiming that. I'm trusting God.