How can you tell if a tumour is a primary source or a secondary source?

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Hi there

We have been faced with a situation about our mum.  She was found to have a tumour in her leg which caused the bone to break.  A biopsy was taken and it was found to be metastatic carcinoma of unknown origin.  

We were told that she also had some dark area in her lung that came on quite quickly and was noticed in a check up x-ray. No further investigation was done. 

So  - I would like to know how is a tumour diagnosed as being primary or metastatic? How do you know?

Mum was referred to a cancer of unknown origin team and who have since come back and said the cancer in the bone was primary. And she doesn't have any cancer anywhere else. 

Which in itself sounds like a really dangerous thing to say.

As the cancer was diagnosed as being secondary there was not deemed to be a need to have additional chemo. 

so actually we do not know if there is any other cancer in her body.

So my logical brain says - what was it about the biopsy that said this is secondary? 

How can one team of people tell her she is dying and the other one say that nope, your tumour was primary.

Please help me understand this.

thank you. 

  • Hello MathsGeek,

    Thanks for getting in touch with us. Welcome to the online community, my name is Linda and I am one of the Cancer Information Nurse Specialists on the Macmillan Support Line.

     

    It’s sounds like you have all been through a difficult time and it’s understandable that it has caused confusion. It can’t have been easy to be told conflicting things about your mum’s diagnosis and emotionally this must have been very stressful for you all.

     

    I hope that this information about How cancer can spread, will be useful. It explains more about primary and secondary cancer too.

     

    Primary bone cancers are a rare type of cancer, so it’s common to think that if cancer has been discovered in the bone that it may be a secondary cancer.

     

    Normally the pathologist can tell that a cancer is secondary by looking at the cells under the microscope. The pathologist can see that the cells do not belong to or originate in the surrounding tissue and this can be confirmed with further lab tests.

     

    With cancer of the unknown primary (CUP) the cells can possibly come from a number of places, but no primary tumour can be found.

     

    It sounds like the dark area in the lungs may have been taken as a primary source.

     

    It’s difficult for us to say why they have changed their minds about the tumour. I would encourage you to ask the specialists how they have come to this conclusion. You mention that the specialists have said she doesn’t have cancer anywhere else, I am assuming from that, that your mum had scans carried out and they were unable to detect any other cancer.

     

    It's common for the specialists to say that they cannot detect any other cancer, if unable to see any on the scans but I appreciate that you feel this is a dangerous thing to say.

     

    You also mention that your mum did not have additional chemotherapy, so I am assuming that she has been treated with some chemotherapy.

    It works systemically, which means that it can potentially destroy cancer cells throughout the body.

     

    I hope this helps.

     

    Best wishes,  

    Linda J, Cancer Information Nurse Specialist  

     

    You can also speak with the Macmillan Support Line team of experts. Phone free on 0808 808 0000 (7 days a week, 8am-8pm) or send us an email.  

    Ref: LJ/ DW