Danielle Duffy, from Netherley, died at Woolton Marie Curie Hospice on Tuesday (12 October), aged just 38.
The mum-of-two was head of social sciences at St Julie’s Catholic High School, and first went to her GP feeling unwell in August of this year.
She then underwent tests before being diagnosed with ‘cancer of unknown origin’ on 7 October at Whiston Hospital.
Cancer of Unknown Primary (CUP) means that doctors do not know where a cancer started in the body before it spread to other areas, which can be because the cancer is too small to be seen on scans, it is hidden beside or behind a larger secondary cancer, or the body’s immune system has cleared the initial source.
Danielle was due to start chemotherapy the following Monday, but she sadly died just five days after her diagnosis.
Her sister, Lisa Wellbeloved, 42, said: "The family and Danielle thought that she was going to start chemo whilst at the hospice.
"We didn’t think she would pass away there.
"She never got a chance to fight it, which is tragic."
Lisa described her sister as "her best friend" and "an amazing mum" to her children Daniel, 7 and Isabella, 3.
She said: "Everything she did was for her children, she adored them.
"They are heartbroken, but they’ve got a permanent guardian angel now."
Fundraising page set up in Danielle’s memory
A Just Giving fundraising page has now been set up by Danielle’s family in her name. So far, it has raised over £2,300.
The funds raised will go towards staff at Marie Curie in Woolton, who Lisa described as "angels on earth". She also said the fundraiser "is what Danielle would have wanted."
Lisa said of the staff at the Hospice’s Sefton Ward: "They didn’t just help Danielle. They helped us. They made an awful time more comfortable."
To donate or find out more about the fundraiser, visit the Just Giving page.