RE: Sr-89, Radiotherapy & cord compression.

[carol marcus <csmarcus@ucla.edu>]

At 07:41 PM 2/8/00 -0600, you wrote:
>Carol and other responding radsafers,
>
>Thankyou for your replies to my query re Sr89 (and thanks to Chris Alston
>for grabbing it from the medphys list and submitting it here for your
>consideration). 
>
>I understand Dr Marcus's reasoning and appreciate that where impending SCC
>is clinically suspected external beam is definitely the way to go. 
>
>Allow me to make my query a little more focused. 
>
>Can anyone suggest a reason or point me to literature that would give any
>radiobiological (or other) basis that could explain how Sr89 (4 mCi) could
>provoke a spinal cord compression in a patient with no clinical neurological
>symptoms prior to the dose administration.  
>
>Regards
>
>Martin Carolan
>Senior Physicist
>Wollongong Hospital
>Wollongong NSW 2500, AUSTRALIA.   
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Dear Martin and Radsafers:

Sr-89 does NOT "provoke" spinal cord compression (SCC).  I tried to make
that clear in my first e-mail, but apparently failed to do so.  It is
contraindicated as a THERAPY for SCC, not as a CAUSE of SCC.

I would also suggest that you stop looking at the package insert as some
sort of fountain of truth.  The physical constant information is usually
correct (but not always---FDA didn't even understand the concept of a
specific gamma ray constant for Sm-153 and demanded the use of a number too
high by a factor of two---and the dosimetry done in recent years is
generally good.  Information about the use of the drug is best obtained from
the USP-Drug Information (D.I.), which has radiopharmaceutical experts,
rather than the FDA, which has very few competent individuals in this area
and those who are there do not have the power needed to create a sensible
package insert in cooperation with the company.  The package insert is a
negotiated settlement between the manufacturer and largely ignorant FDA
employees.  Due to FDA abuse of the Prescription Drug User Fee Act (PDUFA),
radiopharmaceutical indications on the package insert are purposely forced
to be incomplete in order to milk more money out of the manufacturers, which
is accomplished in collusion with the Health Care Finance Administration, a
sister agency to FDA under the Department of Health and Human Services.

Ciao, Carol

Carol S. Marcus, Ph.D., M.D.
<csmarcus@ucla.edu>

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