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Cancer metastases without an identified primary focus are one of the most challenging cases in oncology. They account for about 5% of all malignant tumours. Typically, cancer treatment tactics depend on the primary neoplasm. Without its detection, it is difficult to carry out oncotherapy. In this article, we will discuss how metastases without a primary source are treated and what is the prognosis of the patients.



What is metastatic cancer?

how do cancer metastases develop

The spread of malignant cells from the place where they first formed to another part of the body is called metastasis. This process develops when cells from the primary tumour travel through the blood or lymphatic system. They “settle” in other organs or tissues of the body, where they begin to divide.


Metastatic cells are of the same structure as the ones in the “main” tumour. They usually start growing in the last stages of cancer.


As the cancer progresses, the patient’s condition worsens. They may experience symptoms not only caused by the primary neoplasm but also those areas where the cancer has metastasized.


Metastatic tumours of unknown primary are most often diagnosed in the following organs and systems:


    иконка галочки lymph nodes,  

    иконка галочки liver,  

    иконка галочки spine, 

    иконка галочки lungs, 

    иконка галочки bones, 

    иконка галочки brain.


A new metastatic tumour is the same type of cancer as the primary neoplasm. For example, if breast cancer has spread to the lungs, the malignant cells in the lungs are breast cancer cells, not lung cancer cells. Therefore, the treatment plan is tailored to the underlying disease, not the metastases.

To travel abroad for diagnosis and treatment of malignant tumour metastases without an identified primary focus, please contact MediGlobus coordinating physicians. Our specialists will help you with the choice of medical centre and doctor.

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Diagnosis of metastases and primary tumour

Metastatic tumours with an unknown primary require a comprehensive examination of the body. The choice of diagnostic methods takes into account the localisation of secondary neoplasms and the patient’s symptoms. Doctors may prescribe:


    иконка галочки imaging tests (MRI, CT, PET-CT, ultrasound, X-ray, mammography, endoscopic examinations);  

    иконка галочки laboratory examinations (blood, urine, faeces, PSA in men, etc.);  

    иконка галочки biopsy. 


In 80% of cases, the primary tumour remains undetected throughout treatment. Even with the systematic use of radiological and endoscopic techniques, the primary focus of the cancer is rarely detected. 

Diagnosis of cancer metastases


The primary tumour is diagnosed postmortem in 50-75% of cases. In half of the patients, the cause of secondary malignant foci was cancer of the lung, large intestine, or pancreas. Less often metastases without a primary tumour are detected with tumours of colon and rectum, kidneys, as well as bile ducts and liver. 

Treatment of metastatic cancer of unknown primary

Treatment of metastatic cancer of unknown primary

The ICD-10 International Classification of Diseases code for metastases without a primary lesion is as follows:


    иконка галочки C76 – oncopathology of inexact localisation;  

    иконка галочки C80 – cancer without specification of localisation.  


Treatment depends on the suspected primary foci and is tailored to the individual patient.


It is aimed at alleviating the symptoms of the disease, as well as reducing the main tumour and destroying metastases.


The key treatment options are:


    иконка галочкиchemotherapy,  

    иконка галочки radiation therapy,  

    иконка галочки radiosurgery (CyberKnife and Gamma Knife), 

    иконка галочки targeted therapies, 

    иконка галочки radiofrequency ablation,  

    иконка галочки immunotherapy.

Treatment of brain metastases with an unknown primary

Brain metastases can develop from any type of primary tumour, but some of them have higher risks. Among them are lung, breast, intestine and kidney cancer.


In half of the cases, brain metastases are diagnosed in lung cancer patients, and in 30% – breast cancer. The symptoms vary depending on the localisation of the primary tumour.


Most often, patients with brain metastases suffer from seizures, headaches, dizziness, nausea and vomiting.


Depending on the number of secondary brain tumours and the general condition of the patient, treatment options may include:


    иконка галочки surgery (in rare cases),  

    иконка галочки radiation therapy,  

    иконка галочки Gamma Knife or CyberKnife,  

    иконка галочки chemotherapy. 

лечение метастазов в головном мозге без выявленного первичного очага


The gold standard for the treatment of brain metastases is CyberKnife stereotactic radiosurgery. It makes it possible to remove tumours of any localisation without incisions or opening the skull.

Management of bone metastases of unknown primary

Management of bone metastases of unknown primary

Bone metastases are typically associated with prostate, breast and thyroid cancer. In some cases, they can be caused by oncology of the GI tract, kidneys, ovaries, soft tissue sarcoma and melanoma. Breast tumours account for about 80% of all cases of metastasis to bone tissue. 


The prognosis for treatment of bone metastases is among the most favourable. Oncotherapy can take many years, and in cases of primary prostate and breast cancer, a decade. 


If bone metastases do not cause pain or pathological fractures, they are successfully controlled with drug therapy: bisphosphonates, chemo, monoclonal antibodies and hormonal drugs. If the patient has concerning symptoms, radiation therapy or surgery is advised. 

Treatment of lung metastases of unknown primary

Treatment of lung metastases depends on the spread of cancer, as well as the primary tumour. In most cases, lung metastases are caused by:


    иконка галочки bone sarcoma (25%),  

    иконка галочки kidney cancer (17%),  

    иконка галочки colorectal cancer (15%),  

    иконка галочкиmelanoma (10%),  

    иконка галочкиmalignant breast tumours (9%),  

    иконка галочкиbreast oncology (8%).


Surgery and/or chemotherapy are usually prescribed to control secondary tumours in the lungs. Surgery involves resection of the affected part of the organ. Radiosurgery, radiotherapy, radiation therapy, targeted and hormonal therapy are also recommended for patients with these types of tumours. If metastases cause the formation of fluid around the lung, the patient will need thoracentesis – a procedure to remove the fluid with a special needle. It makes breathing easier.

Treatment of liver metastases without a primary focus

Tumours of the stomach, intestine, breast, lung, prostate, pancreas and melanoma most often metastasise to the liver.


Treatment of such tumours is aimed at eliminating metastatic foci or reducing the symptoms of the disease. For this purpose, resection of the affected parts of the liver, radiofrequency ablation (RFA) and chemotherapy are performed. 


Patients are also prescribed chemoembolisation – the introduction of a special “clogging” drug into the lumen of the vessel. This makes it possible to stop feeding the tumour and thus cause its destruction. 


Prognosis in secondary malignant lesions of the liver, as a rule, is unfavourable. The 5-year survival rate of patients is approximately 11%. 

Treatment of liver metastases without a primary focus

Management of metastases to neck lymph nodes without a primary focus

The treatment of lymph node cancer of unknown primary without metastases to other organs and systems includes surgical removal of these nodes and irradiation of the area. Chemotherapy is also often prescribed. The 5-year survival rate is 12%.


    Prognosis of treatment of metastases without a primary focus

    Most patients with undetected primary tumours and metastases have an unfavourable survival prognosis. The median survival of such patients is 12 months. About 5% of such patients cross the 5-year survival threshold. 

Clinics for the treatment of metastases without a primary tumour





    иконка галочки Metastatic cancer of unknown primary is diagnosed in about 5% of all cancer patients. It is somewhat more common in men than in women. 

    иконка галочки Detection of the primary tumour requires a complex of examinations. Since metastases are often caused by pancreatic, lung and colon cancer, the diagnostics include a chest X-ray, ultrasound and CT scan of the abdominal organs. MRI, PET-CT, laboratory tests and biopsies are also used to make a diagnosis. 

    иконка галочки In the international classification of diseases, metastatic cancer of unknown primary disease has the codes C76 and C80. Treatment of the disease includes chemotherapy, radiotherapy, radiosurgery, surgery, targeted therapy and immunotherapy. The choice of treatment takes into account the primary tumour and the patient’s condition. 

    иконка галочки The prognosis for this category of patients is unfavourable. The average life expectancy is 12 months. 

    иконка галочки Foreign patients come to such clinics as Liv, Sheba, Fuda, SoonChunHyang, Teknon and the University Hospital of Cologne to fight this disease. 


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How to treat metastatic cancer of unknown primary

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