Procedure For Administering Radiopharmaceuticals To Treat The Bone Pain Of Osteoblastic Metastases

1. Patient evaluation and data required for treatment of painful bone metastases a. A bone scan performed within the previous six to eight weeks must show abnormally increased uptake at the painful site(s).

b. Platelet and leukocyte counts must be adequate. The platelet count should exceed 100,000 mL and leukocyte count should exceed 2500-3500/mL.

c. Significant disseminated intravascular coagulation must be excluded with an assay of fibrin split products.

d. Fully informed, written consent, including an explanation of home precautions, should be accomplished, preferably twice, once several days before the treatment. This should include the risks of pancytopenia, the flare phenomenon, and remote risk of death.

e. The painful site should not be treated with radiopharmaceuticals if there is any risk of vertebral compression, epidural metastasis, osteolytic disease destroying 50% or more of the cortex, or evidence of pathologic fracture.

f. Teletherapy is preferred for treatment of single painful lesion.

2. Dosimetric considerations a. Our dosimetric techniques are currently inadequate to have these data be a part of the decision-making process on therapeutic dosage.

3. Choice of radiopharmaceutical a. Sr-89 has been shown to delay the need for repeat therapy and the onset of new painful metastases.

b. Re-186 etidronate has been demonstrated to cause a shorter period of cytopenia than Sr-89, and the same is probably true for Sm-153 lexidronam.

c. P-32 is far less expensive than the other radiopharmaceuticals, can be given orally, and has equal efficacy with no greater risk of death than with Sr-89, Re-186 etidronate, and Sm-153 lexidronam.

d. Thus, there are benefits to the use of any of these radiopharmaceuticals.

4. Special patient preparation a. No premedication or fasting is required.

b. The patient should be well hydrated at home, and should receive about 0.5-1.0 l of any liquid orally or intravenously before treatment to ensure rapid renal excretion.

c. Constipation must be avoided in order to clear Sr-89 and P-32 from the bowel. These agents are not themselves constipating.

5. Dosage administration a. A running intravenous line should be in place. Make sure it works well by infusion of some 50-100 mL of saline solution.

b. A plastic syringe shield should be used, as the production of bremsstrahlung from beta particle interactions with shielding material increases as the atomic weight of the shielding material rises.

c. Gloves and a finger badge should be worn by the individual performing the injection.

d. These radiopharmaceuticals should be given slowly into the intravenous line over two to three minutes, as the mass of the radiophar-maceutical injected may be sufficient to have physiologic effects. Etidronate and lexidronam may chelate calcium and magnesium, acutely but briefly lowering the blood levels of these cations. A bolus of Sr-89 may have calcium-like effects on cardiac physiology. A vial of calcium gluconate should be on hand for rapid administration if cardiac arrhythmias occur.

6. Treatment monitoring a. The patient may return home after the radiation safety officer monitors the patient.

b. The patient should be told that changes in bone pain usually are seen within 7 to 14 days after treatment but may become even more evident over three to four weeks.

7. Side effects a. The patient should be instructed to report any (cytopenia-induced) bleeding episodes, petechiae, sore throat, or fever at once.

b. The patient should be told there is some chance of an increase in discomfort at the painful sites being treated and instructed on what medication he may take to deal with this. He must also be informed that this is not a discouraging sign.

8. Follow-up plans a. The patient should be told to follow-up either with the referring physician or the nuclear medicine physician, if the referring doctor has so indicated, at least every two weeks up to twelve weeks.

b. Platelet and leukocyte counts may be monitored after two weeks.

c. If there is a response to treatment the patient must be told that this is rarely permanent but that more treatments can be given.

9. Instructions to the patient/ radiation safety a. The patient may return home.

b. For P-32 and Sr-89 treatments, there is no need to avoid proximity to one's spouse, children, or pregnant women.

c. For the gamma-emitting Re-186 and Sm-153 there are no convincing data that the patient represents a radiation hazard to anyone, but local radiation safety office precautions should be followed. There should be little reason for couples to sleep apart for more than a day or so.

d. Men should urinate sitting down for several days after therapy, although urinary Sm-153 lexidronam excretion is generally complete well within 24 hours after injection. There is no need for the use of separate toilets.

e. Handwashing for 20 seconds after urination or defecation is suggested.

f. Separate utensils are not needed.

g. Stringent birth control measures should be undertaken for at least six months.

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