Teddi Mellencamp is celebrating after undergoing the final radiation treatment in her battle with cancer

In a post on Instagram, Teddi shared a video showing her ringing the bell and wrote: "Ringing the bell can signify a major phase of treatment - today was my last day of radiation. Five more rounds of immunotherapy to go. Love you all for the kind messages."

Earlier on Thursday, Teddi revealed her final day of radiation treatment came a week later than expected after doctors found more tumours in her brain.

In a post on social media, she explained: "Today's a pretty big day. Today's supposed to be my final day of radiation, granted it was supposed to be last week, but then they found those pesky four more tumors ... I wore a nice shirt ... just in case I do get to ring my bell. I have a pretty good feeling."

The reality star - who has three children and a stepdaughter with her estranged husband, Edwin Arroyave - previously admitted her cancer battle is the "hardest thing" she's ever faced.

She told Us Weekly magazine: "I'm fighting for my life. But also for my family's life and all the people I love. This is definitely the hardest thing [I've faced in my life], but now it feels less hard.

"When I was in the ICU, it was incredibly difficult because I had no memory. One day, I realized it was my daughter's birthday, and I couldn't be there for it; it was really sad. It's still sad when I can't be there for my kids the way I'd normally be."

Teddi added she's been using humour to cope during the tough times, saying: "Everybody wants me to be super positive all the time. One of my coping mechanisms is being sarcastic. I'd rather joke about it and have the best possible outcome than be completely in denial and have my heart broken."