Evaluation of thrombocytopenia in patients treated with rhenium-186-HEDP: guidelines for individual dosage recommendations.
A potential limitation of rhenium-186-1,1-hydroxyethylidene diphosphonate (186Re-HEDP) therapy in patients with painful bone metastases is thrombocytopenia. Given the palliative character of this therapy, it is essential to be able to predict the degree of thrombocytopenia before therapy.


METHODS
Thus far, 39 prostatic cancer patients with multiple painful bone metastases were treated. Twenty-one patients underwent the therapy twice, resulting in 60 therapies. From the pre-therapy 99mTc-HDP scintigram, the bone scan index (BSI) was determined as an index of the extent of bone involvement.


RESULTS
The administered activity ranged from 1104 to 3479 MBq 186Re-HEDP. The platelet count was lowest 4 wk following therapy. From this value and the pretreatment level, the percentage decrease in the platelet count was determined (47% +/- 19%, range 14%-89%). The BSI ranged from 8 to 93. Regression analysis showed a functional relation (R = 0.78; p < 0.001) of the percentage of platelet decrease with BSI and administered activity normalized to standard body surface area.


CONCLUSIONS
Using this relation, it is possible to predict thrombocytopenia by pretreatment bone scintigraphy and to adjust the dosage to each patient to avoid unacceptable toxicity.
de Klerk
J M
JM
Department of Nuclear Medicine, University Hospital Utrecht, The Netherlands.
van het Schip
A D
AD
Zonnenberg
B A
BA
van Dijk
A
A
Stokkel
M P
MP
Han
S H
SH
Blijham
G H
GH
van Rijk
P P
PP
D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000532:radiotherapy* / Q000556:secondary*; D004307:Dose-Response Relationship, Radiation; D012968:Etidronic Acid / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D010976:Platelet Count / Q000528:radiation effects; D011471:Prostatic Neoplasms / Q000473:pathology; D011868:Radioisotopes / Q000009:adverse effects* / Q000627:therapeutic use; D012211:Rhenium / Q000009:adverse effects* / Q000627:therapeutic use; D013921:Thrombocytopenia / Q000209:etiology*
D011868:Radioisotopes; D012211:Rhenium; D012968:Etidronic Acid