Carcinoma of Unknown Primary (CUP) and Tumor Agnostic Biomarkers

CUP is detected, after spreading to another part of the body from where it started, a phenomenon called metastasis. Therefore, doctors use many tests to try and find out where cancer started in the body, which means to find the primary site of cancer origin. Some tests can also determine which treatments may be most effective.

This section describes the CUP diagnostic tests used to find the primary focus. You should know that not all the tests listed below are always selected for each person. Your doctor will consider the following factors when choosing a diagnostic test:

• • • Depending on the type of cancer suspected
    • Your symptoms
    • Your age and general health status
    • The results of previous medical examinations

In addition to the physical examination, the following tests can be used to diagnose CUP:

Biopsy
It is the removal of a small amount of tissue for examination under a microscope. Only histological examination of a biopsy specimen by a pathologist can make a clear diagnosis. The pathologist is the doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs for the definite diagnosis of diseases. Careful evaluation and control of the tumor tissue removed during a biopsy can sometimes provide information about the location of the primary tumor site.

Evaluation, estimation, and interpretation of the pathologist.
The pathologist makes the diagnosis of cancer by examining the tumor sample collected during a biopsy. The pathologist can sometimes predict the primary site of the tumor based on the appearance of the cancer cells under the microscope or based on the results of special techniques, known as immunohistochemistry (IHC), which are also part of a comprehensive histological examination. The result of the histological examination provides important, definitive information about the cancer and helps clinicians plan additional tests and examinations.

When the primary site of cancer cannot be predicted, a molecular test can be performed by Molecular Biologists, aiming to reveal the genetic profile of the tumor. This test uses the tissue sample from the tumor collected during the biopsy. The results of this new diagnostic test are often useful in helping to choose the most appropriate treatment.

Evaluation by an Oncologist
Before CUP can be diagnosed, several tests must be performed to look for the primary site of the tumor. This is called a clinical evaluation and is usually performed by an Oncologist. An Oncologist is a doctor who specializes in treating people with cancer.

The following diagnostic tests can be included in an evaluation:

• • • Blood & urine cancer marker testing (e.g. PSA, CEA testing, etc.)
    • Plain X-ray
    • Computed tomography (CT) or magnetic resonance imaging (MRI) scan
    • PET scan
    • Introspection
    • Mammography

Consult your oncologist for the best personalization for you.

Most people with CUP have 1 of these 4 types of tumors :

1) Adenocarcinoma

Nearly 60% of people with CUP have adenocarcinoma. Adenocarcinoma can develop in the glandular tissue of most internal organs, including the lungs, stomach, pancreas, colon, ovaries, and breast. Because of this, it is extremely difficult for a pathologist to tell where an adenocarcinoma started when it is in a metastatic area.

Additional diagnostic tests on biopsy samples, called Immunohistochemistry (IHC), can predict the primary tumor site in approximately 30% to 40% of cases.

Determining the molecular profile of the cancer in the biopsy sample can be used to predict the primary site of the cancer, in cases where this was not possible with Immunohistochemistry (IHC).

2) Low differentiated carcinomas

Approximately 20% to 30% of people with CUP have poorly differentiated carcinoma. The Pathologist performs additional tests on biopsy samples of these tumors (Immunohistochemistry IHC), because many such cancers can be cured. Similarly with patients with adenocarcinoma, determining the molecular profile of the cancer can help predict the type of tumor of the primary site, being useful in choosing treatment scenarios.

If this test shows that the cancer is lymphoma, germ cell carcinoma, or neuroendocrine carcinoma, then this often means that effective treatments are available.

3) Squamous cell carcinoma

About 5% to 10% of people with CUP have squamous cell carcinoma. If squamous cell carcinoma is found in the cervical lymph nodes in the neck, the primary site of the cancer is often found in the head and neck area. If it is found in the inguinal lymph nodes in the groin, the primary site is often eventually found in the vulva, vagina, cervix, anus, or bladder.

4) Neuroendocrine carcinoma

About 1% to 5% of people with CUP have neuroendocrine carcinoma. The pathologist most often diagnoses this cancer using Immunohistochemistry (IHC). Some of these tumors are aggressive and grow rapidly, but combination chemotherapy can be effective. Others are very slow-growing, and patients sometimes live for several years, even without treatment.

Doctors are working to learn more about CUP, how to prevent cancer, how to better treat CUP, and how to take the best care of people diagnosed with the disease.

Consult your doctor about the best diagnostic and treatment options for you.

Using molecular profiling of tumors to diagnose the primary site of cancer .

Different tissues in the body make different proteins, depending on which genes are active. This is called gene expression. For example, the genes expressed by healthy lung cells are different from those expressed by healthy colon cells. When cancer develops in these organs, it usually shows the same pattern of gene expression, corresponding to the organ (lung, colon).

It is now possible to analyze a tumor sample from a biopsy to understand which genes are expressed. This can predict where the cancer started, that is, predict its primary site.

Personalized therapy based on tumor molecular gene expression profiling is replacing empiric chemotherapy as the standard treatment for patients with CUP who do not fit into any of the specified subgroups (see Types of CUP). Ongoing clinical trials are examining the effects of selected therapy based on tumor molecular gene expression profiling to better define its role in the treatment of CUP.

Targeted therapy

Targeted therapy targets specific molecular alterations within the cancer cell or the environment around and within the tumor. These alterations include gene mutations in the tumor and the abnormal activity of various signaling proteins in the tumor.

Some targeted therapies are approved by the FDA/EMA for specific cancers, either as monotherapy or in combination with chemotherapy. Examples of these targeted therapies include:

-HER2-targeted therapy for HER2-positive breast cancer

-BRAF inhibitors for melanoma with a BRAF mutation

-EGFR inhibitors for non-small cell lung cancer that has a mutation in the EGFR gene, etc.

However, no targeted therapies are currently approved specifically for the treatment of CUP, and targeted drugs approved for other cancers have not been tested for CUP.

Since CUP covers many tumor types, it is possible that some patients will benefit from targeted therapies that have already been shown to successfully treat specific tumor types. For example, therapies that target HER2, which is a molecular alteration found in about 1 in 5 breast cancers, have dramatically improved treatment outcomes in these patients.

Could a patient with CUP who is predicted to have breast cancer have a molecular gene expression profile with an alteration in HER2? If so, could therapy targeting the HER2 alteration benefit this patient? The answer to both questions is likely to be yes.

A recent study found that the incidence of potentially treatable molecular alterations (using targeted therapies already approved for other cancers) is about 25% in CUP. In ongoing clinical trials, people with CUP whose tumors have specific molecular alterations are being treated with drugs that target the abnormality. It is possible that these clinical trials will identify additional effective treatment options for specific patient groups.

Immunotherapy.

In recent years, new drugs that activate the immune system to fight cancer (such as anti-PD-1 and anti-PD-L1 receptor drugs) have been used to treat various types of cancer, such as lung cancer, kidney cancer, head/neck cancer, and certain breast and colon cancers.

Given that most of these types of cancer are represented in the population as cancers of unknown primary (CUP), scientific data suggests that it is reasonable to believe that some patients with CUP could also benefit from immunotherapies.

Other molecular predictors of response to immunotherapy have recently been identified. Patients whose tumors have these predictors (including microsatellite instability MSI or high tumor TMB mutational load) are likely to respond to immunotherapy, regardless of their tumor type. Both of these molecular alterations occur in CUP.

In any case of cancer of unknown primary focus, the findings of a molecular test will help in choosing the most appropriate therapeutic alternative. Possible discovery of gene mutations (determination of the molecular profile of the tumor) will help the Oncologist choose the best possible treatment (targeted therapy or immunotherapy versus chemotherapy, or combinations of the above).

Most of the time, the sample material we are called upon to handle is small because it has resulted from a minimally invasive method (needle biopsy, fluid aspiration, paraffin block with minimal material).

In our laboratory, Pathologists check in a timely manner whether the material to be examined is sufficient. If so, then a management algorithm is followed, with the aim of achieving the performance of multiple tests on the material (Immunohistochemistry, real-time PCR, NGS) in order to fully check the molecular profile of your tumor (proteins, genes, histological Grading).

In this case, and once sample enrichment manipulations have been exhausted, we contact your clinician to discuss alternative approaches in order to obtain the desired information to select the optimal treatment for you. Some examples:

• • • Performing an alternative test (e.g. Immunohistochemistry instead of PCR, or choosing Next Generation Sequencing (NGS))
    • Performing Immunohistochemistry instead of FISH (Fluorescent In Situ Hybridization) and tubulin
    • Possible blood sampling instead of tissue testing (liquid biopsy)
    • Possible option to take a new biopsy or puncture

• • • When the tumor is inaccessible
    • When available tissue is minimal or exhausted (paraffin cube)
    • When the patient cannot support a repeat biopsy
    • When repeat biopsy is not recommended
    • When the patient does not respond to treatment and there is a need for reassessment

LI.B.E.R.O. & LI.B.E.R.O. PLUS detects gene alterations of major clinical significance, which are then used by your Oncologist to personalize your treatment regimen.

A small amount of blood (~20 ml) is taken, as in a routine hematology test. In case the blood collection is not done at Microdiagnostics facilities, the blood should be collected in 2 Streck 10ml vials (please contact us to supply them to you).

Transport conditions: The blood vials are kept at room temperature. Please note that the blood should not be refrigerated, exposed to ice packs, or frozen. After collection, it is recommended that it be transported at Microdiagnostics facilities as soon as possible.

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