Shannen Doherty is opening up about a new development in her fight against cancer.

The Beverly Hills, 90210 alum, who revealed her stage 4 diagnosis three years ago, recently shared that her cancer has metastasized to her brain. Doherty gave the heartbreaking update to her cancer journey on Instagram this week.

"On January 5th, my ct scan showed Mets in my brain," the Charmed alum captioned one video, shared on June 6. "Yesterdays video was showing the process of getting fitted for the mask which you wear during radiation to your brain. January 12, the first round of radiation took place."

Doherty said her "fear is obvious," adding, "I am extremely claustrophobic and there was a lot going on in my life. I am fortunate as I have great doctors like Dr Amin Mirahdi and the amazing techs at [Cedars-Sinai Medical Center]. But that fear…. The turmoil….. the timing of it all…. This is what cancer can look like."

The 52-year-old's emotional post was met with love from friends like Sarah Michelle Gellar, who wrote, "You are a warrior."

Meanwhile, fellow pal Selma Blair wrote, "This is a lot. This is a lot to take on , still again."