The actor and singer - best known for playing Liberty Savage in the E4 soap between 2010 and 2013 - announced on social media that she is to undergo surgery and radiotherapy treatment after consulting doctors about lumps she found on her neck.
Phillips revealed on Instagram: "Just before Easter weekend I had an appointment to see a consultant who sat me down and told me that I had been diagnosed with thyroid cancer, and that I would need surgery and radiotherapy treatment.
"I never thought I would be told that I have cancer at the age of 28, you never think it’s going to happen to you."
The soap star - who is due to undergo surgery in the next week - revealed she had initially been sent away by a GP who dismissed the lumps as minor, due to her age.
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She said: "I booked in with a specialist and immediately she told me she was very concerned due to where my lumps were located and referred me for an urgent biopsy and scans."
Phillips - who competed in The Voice UK in 2017 - urged her followers: "If ever you find a lump or something unusual on your body, never just think it’s nothing, don’t be told that you’re fine by the GP and you’re ‘young’, always get things checked out by a specialist if you can and insist on tests even if it turns out to be nothing, as catching things early is crucial for a good prognosis."
The singer said she is looking forward to being on the road to recovery.
Liberty was introduced to Hollyoaks in 2010 as the sister of Savage brothers Dodger and Will. She was written out on 2013 when she went to Los Angeles to pursue a music career.
The character was reintroduced in 2018 played by Jessamy Stoddart, who is currently appearing on-screen as Liberty.
The 24-year-old model and social media influencer took part in Strictly The Real Full Monty on ITV in 2021.