RE: Sr-89, Radiotherapy & cord compression.

[Karin Gordon <KGordon@exchange.hsc.mb.ca>]

Treatment with Sr-89 could be categorized as continuous low-dose
irradiation, the dose from the isotope in the bone takes weeks to be
delivered and and the palliative effects usually do not appear until about
three weeks or so after administration. As Dr. Marcus indicated, in cases of
imminent spinal cord compression, it is urgent to deliver an large, acute
dose of radiation to quickly halt the tumour progression in the vertebral
body.  If a patient suffered spinal cord compression shortly after Sr-89
therapy administration, it is likely that it would have occurred in the same
time frame without the Sr-89 treatment. Unless you are constantly doing
diagnostic spinal x-rays or bone scans on these patients, you may not be
aware of the severe deterioration of a vertebral body due to rapid tumour
progression.  Occasionally the first symptom of gross metastatic disease in
the spinal column is not pain, but sudden collapse of a vertebral body,
leading to rapid cord compression and paralysis. So it's likely the Sr-89
had nothing to do with provoking the cord compression, rather the timing of
the Sr-89 administration and the cord compression was coincidental and in
this case the outcome might have been more successful if external radiation
had been applied instead. 

Regards from the frozen North
Karin
************************************************************************

Karin Gordon RTR, RTNM, RTT
Radiation Safety Office 
Winnipeg Health Sciences Centre
GC-214, 820 Sherbrook Street
Winnipeg, Manitoba
CANADA, R3A 1R9

phone   (204) 787-2903
fax        (204) 787-1313
e-mail    kgordon@hsc.mb.ca
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-----Original Message-----
From: Carolan, Martin [mailto:CarolanM@iahs.nsw.gov.au]
Sent: Tuesday, February 08, 2000 7:39 PM
To: Multiple recipients of list
Subject: RE: Sr-89, Radiotherapy & cord compression.


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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