My sister had two Golden Retrievers from the same litter. One got a cancerous fatty tumor. My sister drove Molly from Atlanta to Auburn for chemo until she found an veterinary internal medicine specialist in Marietta who was qualified to do chemo. Molly did well on the chemo, but succumbed to the illness. Mandy then got the same type of tumor, and my sister decided against chemo because it didn't extend Molly's life long enough to be worth the expense and the discomfort to the dog.
My standard poodle, Pepper, had a melanoma in one of her toes two years ago. I discovered it because she had a split toenail, and when I googled "split toenail" and "canine," I saw links that said it was a sign of toe cancer, relatively common in black standard poodles. We were advised by a specialist to amputate all three joints in the toe to be extra conservative. The biopsy came back positive for early melanoma. The veterinary oncologist at UGA said that since it was caught so early, she wouldn't recommend chemo. The vet checks all of Pepper's soft tissue and toes every three months, as recommended by the specialist. We keep her out of the sun except for potty breaks.
If she were diagnosed with cancer that was treatable with chemo, I would not hesitate to do it.
Prayers for Cheyenne, you, and your family.