Shannen Doherty's breast cancer has gone to her brain, she claims.

Shannen Doherty of "Charmed" and "Beverly Hills, 90210" revealed on Instagram Tuesday that her breast cancer,

which she was diagnosed with in 2015, has spread to her brain.

The news was accompanied by an emotive video of Doherty, 52, crying as she underwent radiation treatment.

Patients must wear a custom-made mask during the procedure to keep their heads steady so that the lasers can hit the tumor as precisely as possible.

"On January 5th, my CT scan showed Mets in my brain," Doherty explained. "...On January 12, the first round of radiation was administered.

My terror is palpable." Doherty claims she is "extremely claustrophobic" and that "there was a lot going on in my life" at the time of the therapy.

The announcement came a day after she posted another video of herself being fitted for the radiation mask following her CT scan.

Doherty has been battling cancer for several years. She was diagnosed with breast cancer in 2015, after her dog Bowie began to "obsessively sniff" her side.