Tina Knowles battled breast cancer last year — and says she shudders thinking what could’ve happened if it hadn’t been caught early … especially since she’d already missed a scheduled mammogram.

Beyoncé’s mom is opening up about the life-changing ordeal in her new book — “Matriarch: The Memoir” — to PEOPLE and CBS Mornings, saying she finally rescheduled the mammogram she missed during the COVID pandemic … and that’s when docs found two tumors.

She said one tumor was benign, but the other turned out to be stage 1 breast cancer in her left breast … admitting she was in total disbelief — especially since she’s always been on top of her health.

Tina said Beyoncé took the news like a champ — staying calm and focused, even though she could see her mind racing on how to handle it. Solange was a bit more chill, but essentially, Tina said her girls became her team.

She had surgery to remove the tumor last year, along with a breast reduction. She’s doing great now, cancer-free, and credits God for helping her catch it early.