I have a cancerous growth in my upper right lung. I had a biopsy on it and it came back benign. What could this mean?

Uncertain. A cancerous growth cannot be benign. It sounds like they found a lung nodule and biopsied it. If the doctor told you it is benign, then you need not worry. I would check back with your doctor.
Need to be careful. Could be sampling error. Have your doctor talk to the doctor who did the biopsy. May need to repeat biopsy or have an open biopsy. Depends on how suspicious your doctor is. More concerning if pet scan positive.
Possibilities. It could be a benign condition/tumor vs false negative. Two options- if that looks really suspicious i.e. Growing significantly or high FDG uptakes on pet scan-you should consider to see a cardiothoracic surgeon for a video assisted -resection/ biopsy vs-repeat pet/ct or ct scan within a close interval if the lesion does not look suspicious. Please discuss with you doctor the best way to manage.