I bet he's as happy to be home as you are!
I don't know about you, but when I'm worried about my dog and feeling confused, the only thing that will fix it for me is to understand it better. Otherwise my worry just makes me more worried.....
So...
... Here's another good link. Take a look at this inbetween all those Tiny loving sessions that you'll be having this weekend. This may help clear up some of the confusion for you:
http://www.labbies.com/cancer2.htm
Read the first section down through "Cancer Staging", then scroll down and you'll see the section on Lymphoma. This is very informative, but on the technical side (it's hard to avoid getting technical with things like this).
Good luck on Monday, and give that handsome fella some loving from all of us, too!