HEALTH experts at Clatterbridge are calling for greater awareness and more clinical trials on the fourth most common cause of cancer-related deaths in the UK.
"Unknown primary tumours" are diagnosed when oncologists are unable to identify the source of the cancer, as it has spread to other parts on the body by the time a patient is diagnosed.
An estimated 400 people are diagnosed in Merseyside every year, making the cancer's journey even more distressing as patients are unable to identify where their cancer started.
Richard Griffiths, consultant in medical oncology at the Clatterbridge Cancer Centre, said: "Unknown primary cancers are usually very advanced when they first come to light because the primary cancer has given no symptoms.
"This is why the survival rate of this type of cancer is currently very low."
Scans are used to produce detailed three-dimensional images of the inside of the body and are commonly used to work out the best treatment methods for various cancers.
They can show how far a cancer has spread and where it started from, something which is particularly important with unknown primary tumours.
Dr Griffiths continued: "We hope this format of scan will allow us to offer more tailored treatments to our patients.
"It can be an extremely difficult time for patients as they may find it hard to understand how they've lived with cancer for so long without noticing any symptoms.
"It can be hard for healthcare professionals who don't specialise in this area to know how best to diagnose unknown primary cancer as it is not always obvious which are the best tests to perform and this can lead to delays in starting treatment.
"Raising the profile of this cancer group and carrying out more clinical trials could make a significant difference to patients through earlier diagnosis and treatment known to give the best possible outcomes."