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FSR vs. GK:
pros and cons

Also see the our spreadsheet comparing statistics for the two.

• pro: the available data indicates that  for larger tumors, FSR has lower complication rates than GK;

• pro: for smaller tumors, FSR has better hearing preservation rates (see results of study below);

• pro: for most FSR protocols, there are no pins in the head; relocatable masks and mouthpieces are used instead;

• con: FSR has been around for 7 years vs. 30+ for GK, so those who want something proven would might feel more comfortable with GK. For example, the relocatable masks and mouthpieces used for FSR have not been perfected yet, and may create room for error;

• con: FSR is less readily available and is not single-session, which means it is less convenient:  it may be harder to obtain coverage from the insurance company, one may have to travel further to be treated, and one will have to stay there longer;

• con: GK is uniform across all centers, whereas FSR comes in more different "flavors" (see our discussion here), making comparison between centers more difficult.

Here are recent results of a study comparing GK and FSR, by Dr. David W. Andrews et al from the Jefferson University Hospital and the Wills Neurosensory Institute in Philadelphia (based on a write-up in the ANA/NJ Newsletter, August 2002).

During the period 1994-2000, sixty-nine patients were treated using the Gamma Knife and 56 were treated with the Linac (FSR). Patients were treated with GK or FSR depending upon the preference of their physicians, except that patients with very large tumors were assigned to FSR. The GK treatment plan included a 12 Gy tumor margin dose, in line with current practice to keep the dosage as low as possible; and the FSR technique involved 2 Gy fractions delivered over five weeks. significantly higher

The outcomes were very good for both treatments. Tumor control rates were 97-98%. Both treatments achieved high rates of preservation of facial and trigeminal nerve function, and a few patients actually experienced improved nerve function. Preservation of functional hearing was 2.5-fold higher in patients treated with FSR, as measured at 1 year follow-up; the report suggests that immediate FSR treatment may prove preferable to a policy of wait-and-watch for purposes of hearing preservation. Gait disturbance was a post-treatment complaint in three cases; hydrocephalus requiring shunt placement occurred in two cases each for GK and FSR. (Published in the Int'l.J.Radiation Oncology Biol Phys, Vol 50, Aug 1, 2001)

Either system can be an effective way to control an AN if the teams are well-trained and experienced.

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Last Edited: Sunday, December 01, 2002