Tumor Burden and Intraosseous Metabolic Activity as Predictors of Bone Marrow Failure during Radioisotope Therapy in Metastasized Prostate Cancer Patients

Abstract EN

Rationale.

Radium-223-Dichloride (Ra-223) is an alpha-emitter, used to treat bone metastases.

Patients with high metastatic burden and/or with increased trabecular bone uptake could present a higher incidence of hematologic toxicity.

We hypothesized that these two factors are predictors of bone marrow failure.

Material and Methods.

A computer algorithm discriminated between trabecular bone (BVol) and tumor metastases (MVol) within pretherapeutic whole-body skeletal SPECT/CT (N=47).

The program calculated the metastatic invasion percent (INV%) as the MVol/(MVol+BVol) ratio and extracted the BVol mean counts.

BVol counts were correlated to % drop of hemoglobin (Hb), leukocytes (WBC), and platelets (PLT) after 3/6 Ra-223 cycles.

Patient-specific and computational-derived parameters were tested as predictors of hematologic toxicity with MANOVA.

Results.

BVol counts correlated with drop of Hb (R = 0,65, p<0.01) and PLT (R = 0,45, p<0.01).

Appendicular BVol counts showed a better correlation (p<0.05, p<0.01, and p<0.001 for Hb, WBC, and PLT, resp.).

INV% directly correlated with BVol counts (R = 0.68, p<0.001).

At MANOVA, grade III/IV toxicity was predicted by INV% (p<0.01), by long-bone invasion (p<0.005), and by BVol counts (p<0.05).

Conclusions.

In patients with significant bone tumor burden, degree of bone invasion and trabecular bone uptake are predictors of subsequent bone marrow failure.