"My sweet father-in-law has been dealing with pancreatic cancer for the last year and a half. A few days ago he was having stomach issues & was unable to keep anything down," she wrote on Instagram alongside a picture of Kevin in a hospital bed. "His doctors decided to do an exploratory surgery to find the problem, which we thought was just a minor issue. Unfortunately, we were completely wrong. The cancer has spread throughout his entire abdomen. We are so blindsided and still in shock."
Carson continued by explaining that doctors told them that unfortunately they would only have a few weeks left before the cancer takes his life.
"After much heartache and discussion, Kevin has decided to fight it and try another aggressive chemotherapy treatment," she added. "My heart hurts to tell you all that I will not be able to do the DWTS tour this winter. This is an extraordinarily difficult time for us."
"I hope all of you can understand that my place is here with my family. Right now, my focus needs to be on my family & especially on my husband. I want to wish my partner, Frankie, and the whole tour an amazing run. I love my fans & I feel so devastated that I can't be there, but know that my heart is there with you ❤️" she concluded.
ET has learned that Carson will not be replaced on the tour, but the rest of the cast will stand as announced.
Carson and her partner, Frankie Muniz, came in third place during season 25 of the ABC dancing competition.
The duo was a fan favorite this season and last month it was announced that the Malcolm in the Middle star would be joining the dancing troupe on tour, which kicks off later this month.
ET spoke with Muniz about how he's preparing for it. Watch below.