Unknown primary cancer

How is cancer of unknown primary diagnosed? 

For diagnosis of cancer of unknown primary, your doctor will need to do the following things:

  • talk with you about your medical history. This includes discussing symptoms that might point to the source of the cancer, risk factors (e.g. smoking or drinking), and any previous history of cancer

  • perform a physical examination by examining your nose, mouth, throat, thyroid gland and skin for any suspicious areas

  • arrange a referral to a head and neck or ear, nose and throat (ENT) specialist who may order diagnostic tests such as exams or scans for further assessment.

Common tests used include:

examination under anaesthesia 

In some patients, the primary cancer may grow slowly and be too small to be seen on examination and scans; the primary site may appear later during follow-up. Sometimes, a biopsy of the primary site is needed to make sure there is no cancer within them, but examining these areas is often difficult when the patient is awake. The doctor may suggest examining the areas under general anaesthesia (with you asleep) if the primary site of cancer hasn’t been identified. Whilst under anaesthesia, the doctor can perform a thorough examination of the mouth, throat, voice box and the back of the nose (nasopharynx).
Based on the examination, the doctor may recommend:
  • Needle biopsy (Fine Needle Aspiration or FNA biopsy): This is when a thin needle is inserted into the suspicious lymph node to remove a sample. Typically this is performed using ultrasound guidance with local anaesthetic to reduce your discomfort. The tissue is then examined under a microscope to look for cancer cells by a pathologist. This is the only sure way to know if you have cancer. o
  • If a diagnosis cannot be made based on the FNA, it is either repeated or a core biopsy (a similar procedure with a larger needle) may be performed. If the diagnosis still remains uncertain, then a surgeon may perform an excisional lymph node biopsy to remove the suspicious lump under general anaesthesia and send the sample to the pathologist for review. 
  

Ultrasound scan 

This is used to create a picture of the tissues in the neck, and is a very good way to assess the thyroid gland
 
  

CT (Computed Tomography) scan

This uses X-rays to take pictures of the inside of the body. Depending on the clinical situation, patients may require a CT scan of the head, neck, and possibly the chest. Often dye is injected into a vein during the procedure to give clearer images .

 

MRI (Magnetic Resonance Imaging) scan

This uses magnetic fields to take pictures of the inside of the body, however this is less commonly used than CT scans.

 

PET (Positron Emission Tomography) scan

As the cancerous lymph nodes are often too small to detect, PET scan is unable to show the cancer in the lymph nodes. However, using a radioactive form of sugar, PET shows if the cancer has spread elsewhere in the body and could help identify where the cancer has come from (the primary site) .

 

x-ray of jaw bone 

This is part of the dental assessment, which may be needed before treatments.