BBC presenter Rachael Bland, who blogs about having cancer, says her hopes now rest on clinical trials after being told her breast cancer was "incurable".
The 40-year-old said she had become a "lab rat", in her latest post, after starting her first trial last week.
She also revealed she was out with her young son when she received a call with the news that her cancer was incurable.
Bland, who also co-hosts the podcast You, Me and the Big C, was diagnosed with breast cancer in November 2016.
She had months of chemotherapy and radiotherapy in 2017 but required more surgery earlier this year after discovering cancer had spread to her lymph nodes.
The BBC Radio 5 live newsreader and presenter was with her two-year-old son Freddie and his friends at an ice cream farm when she received a call with the results of some biopsies.
On her blog 'Big C little me', she wrote: "My heart raced as I answered it, knowing a phone call did not bode well.
"Then came the words 'I am so sorry, it's bad news. The biopsies have come back showing the same cancer is back and is in the skin'.
"I watched my little Freddie innocently playing away in a tyre in the barn and my heart broke for him.
"I scooped him up and dashed home and then had to break (her husband) Steve's heart with the news that my cancer was now metastatic and therefore incurable."
Metastatic – or secondary – breast cancer occurs when cancer cells spread from the primary cancer in the breast through the lymphatic or blood system to other parts of the body.
Olympic medal winning sprinter Katharine Merry, four-time Olympic rowing champion Matthew Pinsent, and fellow BBC presenter Victoria Derbyshire – who has previously spoken about having treatment for breast cancer – were among those to send their support to Bland on social media.
Bloody hell Rachael. Sending loads of this:
— Victoria Derbyshire (@vicderbyshire) May 20, 2018
End of Twitter post by @vicderbyshire
Other people who have followed her progress since she started writing about her cancer diagnosis responded by saying what an inspiration she had been to them.
One Twitter follower, Tom Millen, said: "I couldn't be more gutted for someone I've never met. May you continue to inspire others as you do me."
Another, Tamsin Edwards, who is also living with cancer, said: "Your podcast has helped me more than I can say: fears about chemo, how to think about the future, effects on partners and the ways cancer affects other people than me.
"We're all in the waiting game – I'm so sorry for your results and wish you well."
Her husband, Steve Bland, said: "I hate that she has to write this so so much… but I'm so very very proud that she did."
I am unbelievably gutted for you Rachael. And your lovely husband and son. The podcast has been such a friend to me since my diagnosis and I am so heartbroken at the unfairness of this for you. Im sure you dont feel it right now but you are so brave. I will pray for you.
— Amanda Steele (@SteeleAmanda) May 20, 2018
End of Twitter post by @SteeleAmanda
I have read your story from the start and Im sorry to read this post but you have every hope and good wish I can offer. Trials are the breakthroughs of the future so I hope this world class teams work hits the jackpot for you xx
— LouiseNicksy (@Nicksy200) May 20, 2018
End of Twitter post by @Nicksy200
Bland told the BBC she had been "absolutely overwhelmed by all the wonderful messages", adding that "whatever happens, I feel like I have such amazing support from everyone".
After going through a strict screening process, Bland started immunotherapy – which works by harnessing the immune system to destroy cancer cells – at the Christie Hospital in Manchester last Wednesday.
She is taking a new trial drug that is designed to make immunotherapy – usually used for other cancers – more effective in treating breast cancer.
It was very early in the process, she said, but she felt "an odd sense of pride" that she was one of fewer than 150 people in the world to test it.
"If it doesn't help me then I hope the data I provide will at some point in the future help others in the same position," she added.
"I feel a bit like a grenade with the pin out… just waiting for some odd sensations to appear. Tick tock."
She said she will stay on the trial if, when she has a scan in six weeks, the cancer is stable or has shrunk, or if it has grown by more than 20% she will be put on a different trial.
"We are waiting and hoping," she said.