Don't sell eggs or birds from your flock, as this would spread the disease.
Here is some information about Marek's disease: https://www.msdvetmanual.com/poultry/neoplasms/marek-disease-in-poultry
How old was she and did she appear sick prior to being butchered?
These tumors could have been caused by Leukosis or Marek's Disease. To know exactly what you are dealing with, send it in to your state vet. laboratory for analysis.
I would not eat this bird.
ETA: And welcome to the BYC...