@cassueriose, If he's healthy enough for the adventure, a second opinion can be very helpful. I've never regretted it, and mine is located a two-hour drive from my home.
Also if he needs it in the future, he'll have an established relationship with another expert.
I'm not a clinician, but I tend to think that unless we have pathology look at the cells of a metastasis, we never really know for sure if it's cancer. But the doctors and radiologists that read the scans are very good at identifying cancer through the images. They usually know even without the pathology, but it's an excellent question for his team, and the second opinion doctor/s too.
How is your family doing? Are they receptive to you, and other, helping during this time?