B2M and neoplasm: These variables include age, treatment, the presence of B-symptoms, tumor grade and stage, bone marrow involvement, bulky disease, hemoglobin levels, lactate dehydrogenase levels, beta-2 microglobulin (B2M) levels, lymphocyte count, monocyte count, the maximum standardized uptake value before the initiation of second-line treatment, undergoing autologous stem cell transplantation, post-transplant maintenance, and elapsed time to transplant from second-line treatment initiation.