This information is about unknown primary tumours (UPTs), which are also sometimes called an occult primary malignancy (OPM). It is only natural to be in a state of shock when you have been diagnosed with cancer. It is all the harder to accept when doctors do not seem to be able to identify where the cancer is. This is a fairly rare situation, but one which can cause a lot of distress.
Primary And Secondary Cancers
A malignant tumour (cancer) is made up of millions of cancer cells. Some of these cells may break away from the original (primary) tumour and spread to other parts of the body where they may form new tumours. These new tumours are referred to as metastases or secondary tumours.
Secondary cancer is usually made up of exactly the same type of cancer cells as primary cancer. This means, for example, that if someone has primary lung cancer that has spread to form secondary tumours in the bones, these bone secondaries will be made up of lung cancer cells. These are quite different from the abnormal bone cells that would form a primary bone cancer. The treatment used for these secondary bone cancers would be designed to treat lung cancer cells, not bone cancer cells.
However, a small percentage of secondary tumours are made up of cells that cannot be identified under the microscope because they look too abnormal, and so it is not possible to tell what kind of primary cancer they have come from.
Unknown Primary Tumours
For most people who have cancer, the primary cancer is easy to identify, as their symptoms will have alerted their doctor to the likely cause, and this will have been confirmed by the tests done at the hospital.
In people with an unknown primary tumour, the tests will have found evidence of a secondary cancer but will not have been able to identify the site of the primary cancer.
Why The Doctors May Not Find The Primary Tumour
There are a number of possible reasons for why the primary might not have been found:
The primary tumour may have disappeared spontaneously because your immune system may have destroyed the primary tumour, but not the secondaries.
The secondaries may have grown and spread very quickly, while the primary is still too small to be seen on x-rays or scans.
The primary tumour may be impossible to see on x-rays or scans because it is hidden by several larger secondaries that have grown close to it.
It is thought that sometimes tumours of the lining of the digestive system may have been passed out of the body through the bowel.
Tests And Investigations
Your doctor will want to do a number of tests in order to try to identify the primary cancer. Exactly which tests you will be asked to have will depend on the clues the doctor has already picked up – for example, the symptoms you have had, your medical history, and where your secondary cancer is. Unfortunately, it is not possible to describe all the possible tests that you may be asked to consider, on this factsheet. However, your doctor should describe to you the purpose of each test.
Tests will probably include an x-ray and a CT scan, blood tests, urine tests and a biopsy (the removal of a small sample of the secondary tumour for examination in the laboratory).
Women may often be asked to have an x-ray of the breast tissue (mammogram) to see whether or not the secondary cancer could be due to a breast cancer.
Tests may be carried out on men and women to see whether or not the cancer started in the lining of the digestive system. These investigations enable a doctor, or specialist nurse, to examine the gullet (oesophagus) and the large bowel (colon and rectum) through a thin flexible tube called an endoscope. The tests used for this purpose are endoscopies and colonscopies. If necessary, a small sample of cells is taken, which can be examined to see if they are normal (biopsy).
These tests can take a lot of time and can be exhausting, particularly if you are feeling ill. You may also find it very frustrating if even the most sophisticated tests are unable to give you an answer.
Information can help to reduce your frustration. Ask your doctor or the other staff looking after you to explain what the tests involve, why they are being done, and what the results mean. If you don’t understand their explanation at first, ask again. You may find it helpful to write down the questions you want to ask.
Unknown Primary Tumours Treatment
Some types of secondary cancers from unknown primaries are responsive to treatment, and you may be offered chemotherapy, hormonal therapy, or radiotherapy, alone or in combination.
Unfortunately, for many people with an unknown primary tumor, by the time it is diagnosed, treatment is unlikely to bring about a cure. If you are feeling well when the cancer is diagnosed, and do not have any troublesome symptoms, your doctor may initially suggest no treatment. This is because it may be better to wait until you really need the treatment. This is not because nothing more can be done, but because the risks and side effects of any treatment outweigh the possible benefits at that time. Your doctor or specialist nurse can discuss this with you further.
Many drugs and other treatments are available to control your symptoms and make you feel more comfortable. These are known as palliative treatments or supportive care. If you have pain, sickness (nausea), or any other distressing symptoms, tell your doctor, or the nurse looking after you, so that they can offer you help and support.
You may want to try a complementary therapy, such as relaxation, visualization, or aromatherapy, which can help to relieve tension and give you back a sense of being in control.
Many different emotions may affect you at this time. Anger, resentment, guilt, anxiety, and fear of the unknown are some of the most common feelings that people may have. You might find yourself sorrowful, anxious, and unfit to rest. You may experience feelings of hopelessness and depression. These are generally ordinary responses, however, it is regularly troublesome and upsetting to confess to them.
You do not have to cope with these feelings on your own; there are people available to help you. Some hospitals have their own emotional support services with specially trained staff, and many of the nurses on the ward will have been given training in counseling. You may feel more comfortable talking to a counselor outside the hospital environment or to a religious leader.