<prompt> The single most important predictor of survival in multiple myelomaIL-6 levelsBence jones proteinuriaCD 138 positivitySerum b2-microglobulin  <response>: Ans. d Serum b2 -microglobulinRef: Robbins 9thpg 598-6028th 608-612b2-M concentration is the strongest and most reliable prognostic factor for multiple myeloma. It depends not only on tumor burden but also on renal function. Elevated b2-M values predict early death 