Many rt. Paratracheal/mediastinal, bilateral hilar nodes consistent w/metastasis. Right subcarinal metastatic node mass 3cm. Max suv 9.1. Lung cancer?

Needs Biopsy. Is there a known primary cancer? If not, you will need a biopsy of one of the nodes. Your doctor may suggest a mediastinoscopy and biopsy to get a tissue specimen. There are other causes of mediastinal node enlargement such as infection and sarcoidosis so it is important to make a definite diagnosis. Good luck.
Biopsy. There are several benign as well as malignant cause of that picture. Bronchoscope and mediastinoscopy are usually diagnostic and low risk. If already proven malignant then primary may be suggested by the histology. Abdominal ct can be helpful to rule out pancreas or bowel lesions.
You report. Part of the story (do you smoke, is there a lung lesion, has there been a biopsy?), and the pet findings mean something is not right, from a benign oddity called sarcoid, to lymphoma, to lung cancer. Share your concern with the doctor ordering the pet scan, and if for whatever reason you mistrust the doctor, get a second opinion.