Journal of Clinical Oncology, 2004 ASCO Annual Meeting Proceedings (Post-Meeting Edition).
Vol 22, No 14S (July 15 Supplement), 2004: 796
© 2004 American Society of Clinical Oncology

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Abstract

The effect of chemotherapy (CT) and external beam radiotherapy (RT) on bone marrow (BM) toxicity of radionuclides in the treatment of bone metastases secondary to breast cancer

University of Pittsburgh Cancer Institute, Pittsburgh, PA; Cytogen Corporation, Princeton, NJ

796

Background: Bone metastases are commonly seen in patients with metastatic breast cancer. Radionuclide therapy has been shown to alleviate the pain of bone metastases but may be associated with BM toxicity, particularly thrombocytopenia. Because many patients with breast cancer and bone metastases also receive CT and RT, we examined the effects of these other treatments on the BM of samarium (Sm)-153-EDTMP (Quadramet®). Methods: A retrospective review of patients (pts) with breast cancer and bone metastases who had received Sm-153-EDTMP was undertaken. Dates of CT and RT, as well as CT regimens were noted. Pre-and post-radionuclide platelet (PLT) and WBC counts were compared, as were the percent decreases in these parameters. Results: Forty-eight pts received 79 courses of Sm-153-EDTMP. Twenty-eight pts received 29 different chemotherapy regimens prior to treatment with Sm-153-EDTMP. Pre- and post-treatment data were available for 21 courses of Sm-153-EDTMP in 20 patients who received CT and RT and for 6 courses of Sm-153-EDTMP in 5 patients who received CT alone. For the entire cohort, the mean ± SEM baseline PLT count was 268 ± 12 x 10³/µL, the mean nadir PLT count was 160 ± 10 x 10³/µL and the mean percent (%) decrease in PLT count was 42%. The mean baseline WBC was 5.8 ± 0.23 x 10³/µL, the mean nadir WBC was 3.7 ± 0.18 x 10³/µL and the mean % decrease was 33%. The mean % decrease in PLT and WBC counts in patients receiving CT and RT was 45% and 41% respectively and the mean % decrease in PLT and WBC counts in patients receiving CT alone was 27% and 35%, respectively. The lowest nadir PLT count was 29 x 10³/µL and the lowest nadir WBC was 1.3 x 10³/µL. Median time to nadir was 28 days. Conclusions: Sm-153-EDTMP is well tolerated in patients with breast cancer who also receive CT and RT. BM toxicity is minimal with relatively small changes observed from pre-radionuclide levels of PLTs and WBCs.

Author Disclosure

Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Cytogen Corp.