Prognostic correlation of plasma cell acid phosphatase and beta-glucuronidase in multiple myeloma: a Southwest Oncology Group study.

In 1982 a randomized trial of either alternating or syncopated VMCP/VBAP regimens for the treatment of active multiple myeloma was begun (Southwest Oncology Group Study 8229/30). A concurrent investigation was undertaken to evaluate the clinical importance and significance of cytochemically stainable plasma cell acid phosphatase (AP) and beta-glucuronidase enzymes (BG). Pretreatment bone marrow aspirates were available for analysis from 399 patients for AP and 398 patients for BG. The AP scores ranged between 42 and 395, and the BG scores ranged between 1 and 346. There was a significant increase of AP (P = .001) and BG (P = .002) in multiple myeloma as compared with a set of patients with benign plasmacytosis. The enzyme scores did not significantly relate to Ig idiotype of myeloma or other prognostic variables except that the BG scores varied significantly with the level of albumin (P = .03) and hemoglobin (P = .01). Analysis of patient groups with different levels of enzyme scores showed that 61 of 398 patients with an AP score of less than 130 had a poorer median survival of 1.7 versus 2.8 years for patients with higher scores (P = .001). In the multivariate analysis of survival, low AP score was an important prognostic factor (P = .006), but BG did not contribute significantly. It is suggested that the subset of patients presenting with low AP should be considered for specialized or more aggressive therapy.