CNS 18 - 39 
RISKS 
The surgical risks depend on how well you/your child are before the operation, and 
the place and size of the tumor. All brain operations may cause bleeding or worsening of 
brain function (such as weakness in arm and/or leg, loss of sense of touch over parts of the 
body, loss of speech, ability to understand, memory). There is also risk of infection and 
even of death. Your/your childs particular risks will be discussed with you by the 
neurosurgeon. 
There are also risks due to the gene therapy. Even though the special mouse virus is 
inactivated, cannot grow and is considered harmless in humans, it is possible that the virus 
may grow and/or make the normal cells cancerous. Since 1989, more than 80 people have 
had treatment with similar viruses and these problems have not occurred. But although we 
think these problems are unlikely, they might happen. 
The special virus may also go into surrounding normal tissue and cause damage when 
you/your child get ganciclovir. This has not happened in any animal experiment or in the 
adults who have been treated so far. 
Ganciclovir may cause side effects. The most common has been a fall in white blood 
cell and platelet counts which increases the risk of infection and bleeding. We will stop the 
ganciclovir if the blood counts drop too much. Ganciclovir can also cause permanent or 
temporary infertility and may be associated with birth defects. Therefore, men and women 
of child bearing age should use contraceptives during and for at least 90 days following 
ganciclovir therapy. 
Following therapy, changes indicating a reaction to treatment mav be seen on MR 
imaging. These changes, may be temporary or long lasting. The changes may be associated 
with temporary or permanent neurologic problems . Because this is an experimental 
treatment there may be other risks that we do not know. 
BENEFITS 
We hope, but we do not know, that you/your child will have a decrease in the size of 
the brain tumor and that the information gained will benefit others. 
ALTERNATIVE TREATMENTS 
You/your child may decline any further treatment. No standard treatment is known to 
be of benefit, but other experimental therapies are available at this and other institutions . 
STATEMENT OF UNDERSTANDING 
1 . I have read the material above and I willingly agree to take part/let my child take part 
in this study. 
2. I have been able to talk as much as I want to with Dr. , who is taking 
care of me or my child , about the reasons for this study and about 
its risks. 
3. I have been told about the other choices for treatment or for no treatment. 
4. I know that this study may have risks that the doctors do not know about now. 
5. I know that I/my child can withdraw from this study at any time. If this happens, 
I/my child can still be treated at St. Jude. 
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Recombinant DNA Research, Volume 18 
