That is EXCELLENT news about the mitotic index. Less than 5 vs greater than 5 is what they use as a cut-off, but "less than 3" is the greatest survival time category.
Unfortunately, there were not clean margins, which increases the risk. These two things combined is why the report says "variable clinical behaviour can be anticipated". Good news is that there is not evidence that it has spread to the lymph system.
Anything you can do to support the body's defense here would probably pay off.
I'm really glad that he is feeling so much better!