Bone involvement is a defining feature of symptomatic multiple myeloma (MM). There is little information on changes in bone mineral metabolism that occur with bisphosphonates and anti-myeloma medication.
Newly-diagnosed MM patients were prospectively enrolled from January to December 2017. Serum bone turnover markers estimation [CTX, P1NP, and Osteocalcin (OC)], DEXA scan, and Tc99 bone scintigraphy were assessed at baseline. Antimyeloma drugs and monthly bisphosphonates were given as per institutional protocol. Bone turnover markers were re-assessed at 3 months.
24 patients were enrolled. Median age was 55 years (35 – 76 years); 79.16% males. Bone pains and anemia were most common [renal failure 45.8% and hypercalcemia 45.8%]. IgG subtype was most common (52%) [IgA 21%, light chain 16%]. 83.3% had ISS stage III disease; mean β-2 microglobulin was 17.81 (± 25.16) mg/mL. 70.83% patients had multiple lytic lesions and 29.16% had baseline fracture. On DEXA scan, 41.67% had osteopenia and 12.5% had osteoporosis. All bone markers showed a graded but statistically insignificant correlation with the extent of bone involvement, P > 0.05. Baseline CTX levels in patients with pathological fractures were significantly higher. Baseline β-2 microglobulin significantly correlated with CTX (r = 0.44) and P1NP (r = 0.43) levels; OC showed no such correlation. At 3 months, a significant decline was seen in CTX levels [0.46 (±0.84) v 1.16 (±1.19), P = 0.001]; minimal rise was seen in P1NP and OC levels, P > 0.05. Fall in CTX levels in patients receiving VTD regimen was significantly greater than VCD regimen, P = 0.012. The decline in CTX among patients exclusively treated with zoledronate was significantly larger than those who received initial ibandronate followed by zoledronate, P = 0.017. At 3 months, overall response rate was 75% [CR 16.7%, VGPR 50%, PR 33.3%].
The bone turnover markers significantly correlated with β-2 microglobulin. Bisphosphonates and anti-myeloma medications considerably reduced CTX (bone resorption marker) but had a trivial effect on P1NP and OC. Larger prospective studies with longer follow up are required to interpret dynamics of bone turnover markers in myeloma.
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