How to deal when a parent doesn't want to know?

My dad had an MRI three weeks ago for a surgery he is having next week. It was clear for what he is having done (a neurostimulator implant for severe nerve damange pain) but there was also a mass found in his mediastinum, deviating the esophagus and trachea. A CT scan 2 weeks later showed the mass had grown transversely 5mm to be 9.1 cm by 6.1 by 4.7. He is having a hard time swallowing food, night sweats, and severe weight loss (he is down to 108 pounds) on top of the nerve damage. They are suspecting either lymphoma or lung cancer and supposed to do a biopsy while he's there for the surgery.

I've been handling his finances since his wife, my step mother, passed away in January of cancer and now he's basically put me in charge of his medical stuff as well. I have permission to speak with his doctors and complete access to his test results online. After reading them myself, I suggested we call his surgeon's office to find out his results and he doesn't want to know. He is scared to find out. I'm not a doctor or nurse so its not my place to be telling him results when I'm not 100% sure what they mean. But I know they aren't good.

How do you help a loved one get through a surprise cancer diagnosis, just months after their spouse died from it? So lost and not ready to lose my dad yet.