The importance of combined hematologic and CT diagnosis for monitoring response in patients with multiple myeloma treated with Bortezomib based therapy

Abstract

8597 Background: To assess the potential role of radiological monitoring (conventional CT) of lytic bone lesions for diagnosis of progressive (PD) or relapsing (R) multiple myeloma (MM) in comparison with laboratory-based diagnosis, soft-tissue based CT-diagnosis and combined hematologic-radiological diagnosis. Materials and Methods: Between 3/03 and 12/07, 201 patients with MM underwent nonenhanced whole-body low-dose multidetector-CT (WBLD-MDCT) survey parallel to hematological follow up (582 investigations). CT-scans were performed using a standardized low-dose protocol assessing number and size of lytic bone lesions (bone window setting, bW) similar to conventional X-ray diagnosis. In addition, number, size and density of medullary and extra-medullary lesions (soft-tissue window setting, s-tW) were analyzed. Progressive or relapsing myeloma was defined by progression of lytic bone lesions, medullary and extra-medullary tumor infiltration and/or of established basic hematologic parameters. Results: 210/582 investigations showed PD or R. 50/210 (24%) yielded the correct diagnosis by all three methods, 50/210 (24%) were diagnosed correctly by WBLD-MDCT (bW), 133/210 (63%) by laboratory-based testing and 195/210 (93%) by WBLD-MDCT (s-tW) as well as by the combination of the latter two. 8/26 assessments of R were biomarker negative. Only 1 of these examinations proved positive on WBLD-MDCT (bW) while the other 7 were correctly diagnosed by WBLD-MDCT (s-tW) due to progress of medullary infiltration and/or extra-medullary manifestation. Of the biomarker-negative assessments of PD (84/210), only 24 (24/84) showed progress of osteolysis on WBLD-MDCT (bW) while all were correctly assessed by WBLD-MDCT (s-tW). Discussion: This retrospective analysis indicates that monitoring of lytic bone lesions in patients with MM is inaccurate for assessment of progression or relapse of multiple myeloma. Due to the effects of specific chemotherapy and accompanying bisphosphonates therapy, progression of lytic bone lesions seems to occur much later in the course of the disease showing slower growth kinetics compared with medullary and extra-medullary myeloma manifestations. No significant financial relationships to disclose.