Rosario Dawson is spending as much time as possible with her father Greg, who has cancer.

While attending the Toronto International Film Festival, where her upcoming series Briarpatch premiered its first two episodes, the actress opened up about her dad’s health for the first time, explaining how she divides her time between shooting and visiting with him.

“My dad has cancer right now, I’ve been leaving every other weekend for his chemo treatments,” Dawson, 40, told PEOPLE. “Yesterday we were filming and they worked it out so I could go home just an extra couple hours so I could be with my dad, and then do my screening, then come over here.”

The star added, “They moved the whole schedule around.”

The actress was adopted as a baby by Greg who began dating her mother while she was pregnant. She has an estranged relationship with her biological father.

Although shooting the USA Network series, in which Dawson plays an investigator who returns to her Texas hometown following her sister’s murder, has been challenging, it’s also been deeply rewarding for the star.

“It’s very demanding. This is definitely one of the harder jobs I’ve ever had,” Dawson said, explaining that in addition to quick turnarounds, they film in such high altitudes that she gets “massive migraines” and drinks chlorophyll water to help with altitude sickness.

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Through the process, Dawson said she’s “getting to grow and develop myself and I’m getting to have insights into my family, into my life.”

“I’m working with incredible folks who just remind me of what it is and why we do what we do and we don’t always elicit this much pleasure from work but this has been really reaffirming and powerful,” she shared. “This has definitely been one of the most beautiful chapters in my life. “

Briarpatch is set to premiere on USA Network in 2020.