Sarah Harding has advanced-stage breast cancer.
The 38-year-old pop star was diagnosed with breast cancer earlier this year and she recently learned it's already advanced to other parts of her body.
Sarah - who is currently undergoing weekly chemotherapy sessions - wrote on Twitter: "Hi everyone,
I hope you are all keeping safe and well during these uncertain times. I've not posted on here for so long, thank you to everyone who has reached out to check in on me, it really does mean a lot.
I feel now is the right time to share what's been going on.
"There's no easy way to say this and actually it doesn't even feel real writing this, but here goes.
Earlier this year I was diagnosed with breast cancer and a couple of weeks ago I received the devastating news that the cancer has advanced to other parts of my body.
"I'm currently undergoing weekly chemotherapy sessions and I am fighting as hard as I possibly can.
I understand this might be shocking to read on social media and that really isn't my intention.
"But last week it was mentioned online that I had been seen in hospital, so I feel now is the time to let people know what's going on and this is the best way I can think of to do so. (sic)"
Sarah thanked NHS "heroes" for their support over recent months and promised she'd "keep positive" amid her cancer fight.
The singer continued: "My amazing mum, family and close friends are helping me through this, and I want to say a thank you to the wonderful NHS doctors and nurses who have been and continue to be heroes.
I am doing my very best to keep positive and will keep you updated here with how I'm getting on.
"In the meantime I hope you'll all understand and respect my request for privacy during this difficult time.
Sending you all so much love....xx (sic)"