She wrote: "After a pretty weird end to 2018 I was looking forward to taking on some exciting new adventures in 2019 ... and boy has the universe delivered.
"I found a lump and had it checked in Jan, and then found myself playing the world's worst waiting game. The results came back and instead of balling my eyes out or going into shock, I somehow just went ok ... what's next? I've been business mode Gandy, crying mode Gandy, scared of needles mode Gandy and cracking bad jokes to doctors Gandy. I'm alive and I intend to keep it that way."
"Please please please check your boobs, and if you're like "ummm maybe that's something, or nah nah, it's probs nothing" er on the side of something and go see your GP! Mammograms are not scary," she said.
"If you do have cancer it's ideal to find it and kick it's ass before it has time to even get a look in."
Friends and fans have rallied around Gandy sharing words of encouragement.
"Gandy, I am so sorry to hear this, holy sh*t. You're positivity is going to get you through this girl," wrote ZM host Megan Papas.
"Sending big love and positivity your way," says Laura McGoldrick.
"Ok universe that's a move. I'm gutted you are going through this but already uplifted and amazed at your strength and determination. Kia kaha koe," wrote Stacey Morrison.