The effect of bone and bone marrow involvement in PET CT and plasma cell ratio in bone marrow biopsy on prognosis in multiple myeloma patients

ABSTRACT THE EFFECT OF BONE AND BONE MARROW INVOLVEMENT IN PET CT AND PLASMA CELL RATIO IN BONE MARROW BIOPSY ON PROGNOSIS IN MULTIPLE MYELOMA PATIENTS Multiple myeloma (MM) is a type of malignancy characterized by the uncontrolled proliferation of plasma cells in the bone marrow. It clinically presents with renal failure, lytic bone lesions, hypercalcemia, and anemia. The prognosis of this disease depends on various factors. The involvement of bone and bone marrow in PET/CT and the plasma cell ratio in bone marrow biopsy play critical roles in assessing the severity of the disease and the response to treatment. This thesis examines the relationship between the prognostic values of bone involvement and metabolic activity level (SUVmax) in PET/CT at diagnosis and the plasma cell ratio in bone marrow biopsy in MM patients, as well as factors affecting survival. A total of 48 patients diagnosed with multiple myeloma and followed up at the Hematology clinic of Fırat University Medical Faculty Hospital between January 2015 and May 2023, aged 18 and over, were included in the study and their data were retrospectively analyzed. The study included 48 patients, of whom 25 (52.08%) were female and 23 (47.92%) were male. The median age at diagnosis was 61.5 years (41-80). Upon evaluation of the patients' CRAB findings at diagnosis, 31% had bone involvement, 17% had anemia, 10% had hypercalcemia, and 6% had renal failure. When patients were evaluated based on the presence of bone involvement according to M protein type, no statistically significant difference was found between the groups. However, despite the lack of statistical significance, the proportion of bone involvement was higher in those with the kappa light chain type (12.9% with bone involvement vs. 5.88% without, p=0.087). No significant relationship was found between bone involvement and gender (p=0.83). There was no significant relationship between the plasma cell ratio being above or below 50% and the presence of bone involvement (p=0.99). A weak relationship was found between bone involvement and albumin (p=0.08). A strong relationship was found between the plasma cell ratio and hypercalcemia (p=0.0082). Laboratory findings showed that albumin and a plasma cell ratio of 50% or higher had an impact on bone involvement (p=0.075, a weak relationship). The number of patients with bone involvement and SUVmax <5 was 12 (25%), and the number with SUVmax ≥5 was 19 (39%). A strong statistical relationship was found between bone involvement and SUVmax ≥5 (p=0.00012), while weak relationships were observed between bone involvement and M-protein type kappa and albumin levels (p=0.087 and p=0.080, respectively). No significant relationship was found between the response to first-line treatment (partial response and above vs. below partial response) and bone involvement or plasma cell ratio (p=0.99 for bone involvement, p=0.107 for plasma cell ratio). The median treatment duration for patients with bone involvement was 39 months (1-106) and for those without was 35 months (1-95). No statistically significant relationship was found between bone involvement and survival (p=0.612). The median survival time for patients with a plasma cell ratio ≥50% was 37 months (1-105), and for those with a ratio <50% it was 38.5 months (4-106). No significant difference in survival times was found based on whether the plasma cell ratio was ≥50% (p=0.773). The median survival for patients with SUVmax ≥5 was 43 months (4-106) and for those with SUVmax <5 was 36 months (1-65). No statistically significant difference in survival times was found based on whether SUVmax was ≥5 (p=0.271). A strong relationship was found only between the plasma cell ratio and hypercalcemia among the CRAB findings (p=0.0082). A strong statistical relationship was found between bone involvement and SUVmax ≥5 (p=0.00012), while weak relationships were observed between bone involvement and M-protein type kappa and albumin levels (p=0.087 and p=0.080, respectively). No significant difference was found between the plasma cell ratio or SUVmax and survival times. Keywords: Multiple Myeloma, PET/CT, Bone Involvement, Bone Marrow, Plasma Cell Ratio