The serum-free light chain assay cannot replace 24-hour urine protein estimation in patients with plasma cell dyscrasias.

indolent nature of relapse in this genetic subtype. Our observations suggest that although the composition of the various genetic subtypes at diagnosis and relapse appear similar, the prognosis of some subtypes (especially t(11;14)) can be markedly different at relapse when modulated by secondary events (eg, increased proliferation), whereas others (such as hyperdiploid MM) appear to behave similarly at diagnosis and relapse. Our observation also has important therapeutic implications as it suggests relapsed t(11;14) should be treated aggressively and drug combinations or addition of new agents may be more appropriate for these patients. On the other hand, bortezomib seemed to be an effective therapy in relapsed t(4;14) patients, improving the prognosis of these patients to that of genetic subgroups with good prognosis. Our observations highlight the fact that different treatment strategies may be needed for newly diagnosed and relapsed patients even within the same genetic subtypes. Wee J. Chng, George Mulligan, Barbara Bryant, and Leif Bergsagel