The 47-year-old actress discovered her health issues in February after undergoing a full-body MRI scan but her primary care physician originally tried to talk her out of it.
She told PEOPLE: "I didn't know why I wanted to get this scan except for the fact that I just did."
After her primary care doctor insisted that she didn't need the scan, due to her age and good results from her annual physical, Busy consulted her cousin's husband, Beverly Hills internal medicine physician Dr Justin Donlan, who told her "knowledge is power".
Philipps explained: "What he said really resonated with me. I think that that really speaks to us as women. We are frequently told by doctors that there is nothing to worry about and you kind of know that there's something to worry about.
"I do think that that is something that I hope, especially women, can take away from my experience. First of all, there's nothing to be afraid of in having information. It's only empowering. Secondly, if you feel anything, don't let some doctor be like, 'You don't need to do it.' That's a waste of time. See things through if you can.
"Ultimately, we, as humans, have the ability to be in touch with what is going on inside of our own bodies if we're able to recognise it and listen to ourselves. Frequently, we dismiss ourselves."
The scan revealed a mass on Philipps' brain, which was revealed to be a grade 2 oligodendroglioma, found in just 1100 to 1300 people per year in the US.
Philipps also revealed that her friend and Dawson's Creek co-star Michelle Williams reminded her that she had felt like something was wrong for some time.
She said: "When I first told her and she said, 'Busy, you have been saying for the past two years, My brain feels broken.' And she was right. I have. I've been saying this for the last few years. I don't know, my brain feels broken.
"(Now) my brain does not feel broken anymore. I'm kinda like good to go."
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