Carcinoma of Unknown Primary

A diagnosis of carcinoma of uncertain primary is made when the cancer's origin cannot be determined. Most frequently, cancer is identified when medical professionals locate the site of cancer's onset (the primary tumor). Such locations may also be found if cancer has spread (metastasized). Doctors can locate the cancer cells that have spread throughout the body in carcinoma of unknown primary, also known as the occult primary cancer, but they are unable to locate the underlying tumor.

While selecting the best therapies, doctors take the original tumor's location into account. Hence, if a carcinoma of an unknown source is discovered, medical professionals attempt to pinpoint the main tumor location. While attempting to pinpoint the origin of your cancer, your doctor may take into account your risk factors, symptoms, and outcomes from examinations, imaging tests, and laboratory testing.

Carcinoma of Unknown Primary: Causes

Cancer often develops when cells experience Genetic alterations (mutations). Cells receive their instructions from the DNA. When normal cells would normally die, some mutations can make a cell proliferate uncontrollably and keep it alive. When this occurs, the aberrant cells gather and develop into a tumor. The tumor cells can separate and disperse (metastasize) to other bodily regions.

Cancer cells that have spread to other body areas are observed in carcinoma of an unknown source. Yet, the primary tumor is not located. This may occur if:

  • Imaging scans are unable to detect the primary malignancy because it is too tiny.

  • The body's immune system was able to eradicate the initial malignancy.

  • The first malignancy was eradicated during surgery for a different condition.

Carcinoma of Unknown Primary: Symptoms

Depending on which body area is affected, cancer of unknown origin might present with various signs and symptoms. In general, they might consist of −

  • An unnoticeable bulge under the skin

  • Pain

  • Alterations in bowel habits, such as diarrhea or new, recurring constipation

  • often urinating

  • Cough

  • Fever

  • Sweats at night

  • Shedding pounds without trying

Carcinoma of Unknown Primary: Risk Factors

The major risk factors include −

  • Aged. Those over 60 are more prone to develop this form of cancer.

  • Cancer in the family. There is some evidence to suggest that carcinoma of unknown origin may be linked to a family history of lung, renal, or colon cancer.

Carcinoma of Unknown Primary: Diagnosis

The following examinations and techniques are used to determine primary cancer's origin −

  • Exam of the body. To determine your diagnosis, your doctor may inquire about your signs and symptoms and inspect the region that worries you.

  • Image-based exams. To aid with your diagnosis, you could have imaging tests like an X-ray, CT scan, or MRI.

  • Removing a tissue sample for analysis. Your doctor could suggest a treatment to extract a sample of cells for lab testing to determine if the symptoms you are experiencing are due to cancer (biopsy). You might need to have surgery or have a needle inserted through your skin to do this. Doctors will examine the cells in a lab to determine whether or not they are malignant and to determine their possible origin.

You could undergo further testing to hunt for the location where the cancer cells originated if initial tests reveal that cancer cells originated from another part of the body (the primary tumor).

Tests might consist of −

  • Exam of the body. Your body will be meticulously examined by your doctor to check for cancerous lesions.

  • Image-based exams. To check for indications of the primary malignancy, your doctor can advise imaging testing. CT and positron emission tomography (PET) scans may be part of these examinations.

  • A blood test. Blood tests that gauge how well your organs are functioning might provide your doctor with hints about whether cancer may be harming your kidneys and liver, for example. Tumor markers, which are substances that some cancers generate sometimes in the blood, may help your doctor make a more accurate diagnosis. Prostate-specific antigen (PSA) for prostate cancer and cancer antigen (CA) 125 for ovarian cancer are two examples of tumor markers.

  • Using a scope to look into the body. To check for symptoms of cancer, the doctor may inspect the interior of your body using a long, thin tube fitted with a camera. To check the interior of your lungs, esophagus, stomach, liver, or small intestine, the scope may be introduced through your mouth. The scope can be put into your anus to inspect the colon and rectum.

Carcinoma of Unknown Primary: Treatment

The doctor may suggest the following treatments based on the severity of the condition −


Drugs are used in chemotherapy to destroy cancer cells. One or more chemotherapy medications may be ingested orally, injected intravenously through a vein in your arm, or both. If you have cancer cells spread throughout your body, chemotherapy may be advised.

Radiation Treatment

High-powered energy beams from sources like X-rays and protons are used in radiation treatment to destroy cancer cells. You lie on a table during radiation therapy as a machine rotates around you, sending radiation to specific areas of your body.

Cancer of an unknown source that is localized to one place of the body may be treated with radiation treatment. Moreover, it can be used to assist manage symptoms, such as the pain brought on by a malignancy that is advancing.


If your carcinoma of the unknown source is confined to one place, such as a lymph node or the liver, surgery to remove cancer may be a possibility. After surgery, your doctor can advise radiation to eradicate any cancer cells that might have persisted.

Palliative (Supportive) Care

Palliative care is a type of specialist medical treatment that concentrates on relieving pain and other severe sickness symptoms. Specialists in palliative care collaborate with you, your loved ones, and your other medical professionals to add an extra layer of support to your continuing treatment. When receiving more invasive therapies like surgery, chemotherapy, or radiation therapy, palliative care can be employed.

Carcinoma of Unknown Primary: Prevention

Some risk factors can raise your chance of cancer, just like they might for other malignancies. But, whether you have risk factors or not doesn't mean you will develop cancer. Nevertheless, there are several recognized cancer risks that you may take action on to enhance your overall health and perhaps reduce your chance of cancer, such as −

  • If you smoke, put an end to it. Several malignancies are more likely to develop in smokers.

  • Consume a diet rich in fruits, vegetables, beans, and other legumes, as well as lean proteins.

  • If you are overweight, lose weight.

  • To lower your chance of developing skin cancer, dress in protective clothes such as caps and sunscreen.

  • Continue to be active.

  • Minimize your alcohol consumption; men and women should each only have two alcoholic drinks every day.


The likelihood of curing carcinoma of unknown primary (CUP) is lower than curing primary cancer since CUP is not original cancer and has already spread when it was discovered. Individual survival rates range from a few months to many years.

Life expectancy is influenced by several variables, such as −

  • Where the cancer is located.

  • How far it has migrated to different tissues and organs.

  • What kind of cancer cells are present and how atypically do they appear under a microscope?

  • Your overall well-being.

  • Your reaction to previous medical treatments.

Dr. Durgesh Kumar Sinha
Dr. Durgesh Kumar Sinha


Updated on: 29-Mar-2023


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