Pollex shared the news Wednesday on Twitter, asking her followers to keep her in their prayers.
"Big surgery Friday. Will have my family, friends and @MartinTruex_Jr by my side," she tweeted. "Just say a little prayer for me that it goes well."
Truex Jr.'s spot in Friday's event will now go to Matt Crafton, the reigning Camping World Truck Series champion. Truex Jr. is expected to join his Furniture Row Racing team Saturday and to compete in Sunday's Sprint Cup Series race.
Pollex has been an avid cancer advocate, specifically childhood cancer, even before her diagnosis. She and Truex Jr. have hosted Catwalk for a Cause to benefit children with pediatric cancer in Charlotte, N.C., since 2007 in addition to running the Martin Truex Jr. Foundation, which is "hooked on helping" "children stricken by illness, poverty and neglect."
"Sherry's passion is helping children, and specifically those fighting pediatric cancer," read a statement on the foundation's website. "Her involvement is well known, as she is the creator of the Foundation's annual Catwalk for a Cause. If you would like to honor Sherry, please consider making a donation towards Pediatric Cancer Research."
Thank you so much for all the prayers!!! I'm going to need them. But I'm a fighter. I can beat this!! Cancer picked the wrong chick— Sherry Pollex (@SherryPollex) August 13, 2014