Shannen Doherty's oncologist details the final days of the "incredible warrior"

Days after her death on Saturday, July 13, from stage 4 breast cancer, Shannen Doherty 's oncologist-turned-friend Dr. Lawrence D. Piro is telling People about the final days in the life of the "incredible warrior."

Dr. Piro, with Cedars-Sinai Medical Center in Los Angeles, became a close friend of the Beverly Hills, 90210 alumna in her yearslong fight with the disease.

"In her mind, she was not wanting to consider any other alternative than 'we were beating this," he tells the magazine.

Dr. Piro explains ultimately, "things turned much more difficult in the last couple of weeks," adding, “We kept going until we couldn't go any more."

He expressed, "The last conversation that we had, she was in the process of realizing that things had taken a pretty significant turn ... She wanted to continue to take treatment and fight through, even though her physical condition had taken a bit of a downturn. And so we did."

Piro recalled, "In the last few hours, she was in a place where she was very comfortable and sleeping and transitioning, and she was surrounded by some of her very close friends," adding her dog Bowie was also with her.

"The room was surrounded by a select group of friends that were giving her a lot of care and support," he said. "It was somber and sad, but beautiful and loving. The hardest thing about this was that she wasn't ready to leave because she loved life."

Dr. Piro said Doherty felt "misunderstood most of her life," and "would want us to live our lives as strongly as we can, committed to our convictions and to not allow others to label you or to misrepresent you and stop you from living your best life."