The goal of this clinical trial is to evaluate whether iopofosine I 131 is more effective than the combination Rituximab-Cyclophosphamide-Dexamethasone (R-CD). The main question the study aims to answer is:
• Does iopofosine I 131 work better than R-CD when looking at the length of time during and after the treatment that a patient lives with WM but it does not get worse.
Participants will:
* Be randomly assigned to received either iopofosine I 131 or R-CD.
* If assigned to iopofosine I 131, have it administered via infusion 2 times each cycle for a total of 2 cycles (each cycle is about 3 months long).
* If assigned to R-CD, it will be administered for up to six cycles, and each cycle is 3-weeks long
* Visit the clinic once every 3 weeks for checkups and testing.
* Report any side effects or new medications.