Gammaknife-discontinuance of zalkori for surrounding days - 1262984

Fri, 03/28/2014 - 04:33

Hi there

I am having gamma knife in 10 days for two tiny brain mets, saw my oncologist yesterday and she suggested coming off crizotinib for a couple of days before and after the Gammaknife, she said the discontinuance was precautionary and there was no evidence about it. I wondered what views other oncologists /neurosurgeons had about this, Is there any risk of a flare or the cancer having an opportunity to become more aggressive if I am off zalkori for five days or is a gap of this duration of no concern? tThank you Alicia

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Hi Alicia,

In the context of a Xalkori treatment break necessitated by difficulties with side effects from the drug, Dr. West has said:

"I don’t hesitate to offer a break for people with good control. There is some risk of a “flare” of rapid progression — sometimes the cancer can rebound and progress readily after a few weeks off of it if a significant amount of tumor burden is has been effectively suppressed by the targeted therapy and suddenly isn’t. But if my patient needs a break, for whatever reason, I just have them be ready to restart it in the event that they develop rapid worsening of cancer-related symptoms. Otherwise, they can enjoy a break from the side effects and will often do just fine." -

A few days is unlikely to be a problem.

Good luck with the Gamma Knife.

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Dr West

I would say in a situation in which there is no data, you'll see some doctors doing just about everything, but I think the majority would favor holding XALKORI (crizotinib) during brain radiation, even if it's over a few weeks, let alone just a one-day treatment like stereotactic radiosurgery (SRS, also sometimes known as Gamma Knife or Cyber Knife). With SRS, it's a very high dose all at once, so the potential harmful effect of a negative interaction is great, and the time off is very minimal. I am very much inclined to favor a break of at least a day or two before and after SRS, and I think the risk from that break is exceptionally small. One point to make is that XALKORI doesn't get into the brain very effectively, so the risk of overlapping side effects are likely very small, but it's so unstudied and the potential of making a bad assumption so great that I do not see any remote reason to have the treatments overlap.

-Dr. West