It is true that Fred has a relatively rare form of Non-Hodgkins Lymphoma, that is indolent, (slow to progress), and he has never had symptoms that made him ill. However, his doctors haven't really discussed his prognosis in detail.
His form of lymphoma is called nodal marginal zone lymphoma .
The prognosis of nodal marginal zone lymphoma is discussed in a recent review article . 5-year survival is estimated at 50-70%.
Thompson's prognosis would appear to be better than the average 30-50% likelihood of death within 5 years of the diagnosis (he was diagnosed in 2004), as his appears to have been initially treated at an earlier stage, he has gotten this far without evidence of early transformation into diffuse large B-cell lymphoma, and he has been treated with newer immune medications not available at the time these survival studies were done. More detail about the pathology would need be available to better estimate a prognosis (and such records really should be made available). Based on the information that is available, it cannot be said that his NHL is not life-threatening.