Radionuclide Therapy for Palliation of Bony Metastases

Radiopharmaceuticals approved by the Food and Drug Administration:

§        89Sr strontium chloride

§        153Sm-EDTMP

§        32P-Na phosphate

Typical Injected Dose:

§        4 mCi of 89Sr strontium chloride

§        1 mCi of 153Sm-EDTMP

§        4 mCi/kg of 32P-Na phosphate

Physical Characteristics of 89Sr and 153Sm and 32P

 

 

32P

89Sr

153Sm

t1/2

14.3 days

50.5 days

46.7 hr

mode of decay

b-

b-

b-

Emax

1.73 MeV

1.463 MeV

0.803 MeV

Range in tissue

8 mm

7 mm

5 mm

General information

§    Sr-89 is a bone localizing calcium analog with distribution very similar to 99mTc-MDP

§    Sm-153 EDTMP is a bone localizing phosphate analog  with a distribution very similar to that of 99mTc-MDP

§    Ratio of metastatic lesions to normal bone =  5:1

§    Ratio of metastatic lesions to marrow  =  10:1

§    Retention of 89Sr and  153Sm  in metastases is significantly longer than in bone

§    No reported adverse reactions

§    30-50% of patients have measurable decrease in WBC and platelets

§    Recovery begins at about 6 weeks

§    Flare phenomenon (increased pain for a few days early in the course of treatment) is often prognostic indicator of successful treatment

§    80% Response rate overall for both drugs

§    Sm has a gamma ray usable for imaging

§    Sm has a more rapid onset of relief than Sr-89, but a shorter mean duration of effect than Sr-89

§    Up to 80% patients experience relief- onset of effect at 10 to 20 days for Sm-153 and 15-25 days for Sr-89

§    20% of prostate Ca patients become pain free

§    Average duration of effect is up to 6 mo

§    Range of relief was between 4 and 12 mo

§        Greater success with prostate cancer than breast cancer

§        Retreatment no sooner than 90 days (if a minimal effect has been obtained, retreatment at 30-45 days may be indicated)

§        Osteosarcoma outcome questionable- usually not beneficial

 

Radionuclide Therapy: Clinical Outcomes

 

80% response divided into 3 groups, based on pain and medication diaries

moderate response:    morphine moving down to codeine

marked response:       morphine moving down to advil

dramatic response:     morphine moving down to no drugs