For brain cancer what is the typical survival rate grade 3 anaplastic astrocytoma. All I have found is 3-5 years?

MAY be longer. My wife had a 6cm grd 3 astrocytoma in 2000. She had surgery, radiation and chemo. She remains in remission.
That's right. I'm sorry to tell you that 3-5 years is right, but remember that's an average. That means some people live longer than 5 years, and some don't live as long as 3 years. Each person is different, and survival depends on many factors. Ask your doctor to be honest with you along the way, and keep hoping... There are new treatments for astrocytoma every day! Best wishes!
Generally true. There are many new molecular markers for the grade 3 anaplastic astrocytoma that suggest that the outcomes may be improved. One of the newest is the idh1/2 set of mutations. The astrocytomas that have these have a better response to the treatments and have a longer survival rate. There are new targeted therapies against the hedgehog genes that hold some promise. Keep watching for trials.
Options. 3-5 is median survival - so it can be more or less in different individuals. Ask your doctor if there is an "oligo" component in the astrocytoma, which makes the tumor more responsive to radiation. Also ask if a mgmt mutation study may be indicated in this case.