What is MYC?

Reviewed by Pathologists on:
December 30, 2025

MYC is a gene that provides instructions for making the MYC protein, which plays a major role in controlling how cells grow, divide, and use energy.

MYC is considered a biomarker. A biomarker is a measurable feature in a tumour, such as a gene change or protein abnormality, that helps doctors understand how a cancer behaves and how aggressive it may be.

What is the function of MYC in normal cells?

In normal cells, the MYC protein acts as a growth regulator.

MYC helps control:

• How quickly cells divide.

• How cells make proteins.

• How cells use nutrients and energy.

MYC activity is normally tightly regulated. It turns on when cells need to grow and turns off when growth is no longer needed. This balance helps maintain healthy tissue function.

What types of cancer are associated with MYC?

Abnormal MYC activity is seen in many types of cancer, but it is essential in lymphomas, including:

• Burkitt lymphoma.

• Diffuse large B-cell lymphoma (DLBCL).

• High-grade B-cell lymphomas, including “double-hit” and “triple-hit” lymphomas.

MYC abnormalities can also be found in leukemias and many solid tumours, such as cancers of the breast, lung, colon, and brain. However, the clinical meaning of MYC changes depends on the cancer type.

How does MYC cause cancer?

Cancer can develop when cells grow too quickly and escape normal controls.

When MYC becomes abnormally activated, it sends constant signals that push cells to divide rapidly. This can happen through:

• MYC gene rearrangements, where MYC is placed next to highly active genes

• Gene amplification, which increases the number of MYC copies

• Increased MYC protein expression, even without a clear gene rearrangement

Excessive MYC activity drives rapid cell growth and increases the risk of additional genetic damage, which can lead to aggressive cancer behavior.

Why do pathologists test for MYC?

Pathologists test for MYC because it is an important diagnostic and prognostic biomarker, particularly in lymphomas.

MYC testing can help:

• Identify highly aggressive lymphomas.

• Distinguish Burkitt lymphoma from other lymphomas.

• Classify lymphomas as high-grade B-cell lymphoma when MYC changes occur together with BCL2 and/or BCL6 abnormalities.

• Estimate how fast a tumour is likely to grow.

MYC results can influence treatment intensity and clinical management.

How do pathologists test for MYC?

MYC testing is performed on tumour tissue obtained from a biopsy or surgery. Several laboratory methods may be used, depending on the clinical situation.

Common testing methods include:

• Immunohistochemistry, which measures how much MYC protein is present in tumour cells.

• Fluorescence in situ hybridization (FISH), which looks for MYC gene rearrangements.

• Molecular testing, such as next-generation sequencing, is used in selected cases.

In lymphomas, immunohistochemistry is often used as a screening test, while FISH is used to confirm gene rearrangements.

How do MYC results appear in a pathology report?

MYC results are usually found in sections of the pathology report titled immunohistochemistry, biomarker studies, or molecular testing.

Results may be reported as:

• MYC positive, meaning increased MYC protein expression.

• MYC negative, meaning low or absent protein expression.

• MYC rearrangement detected, if a gene rearrangement is identified.

• No MYC rearrangement detected, if genetic testing is negative.

The report may also include a comment explaining whether MYC is involved in the definition of high-grade or aggressive lymphoma.

How does MYC fit with other lymphoma biomarkers?

MYC is almost always interpreted together with other lymphoma biomarkers.

MYC is commonly assessed alongside BCL2 and BCL6. When MYC rearrangements occur together with BCL2 and/or BCL6 rearrangements, the lymphoma may be classified as a high-grade B-cell lymphoma, often referred to as a “double-hit” or “triple-hit” lymphoma. These lymphomas typically behave more aggressively.

MYC protein expression is also interpreted with markers such as Ki-67, which measures how fast tumour cells are dividing, and CD10, BCL6, and MUM1, which help determine the cell of origin.

By combining MYC results with other biomarkers, pathologists can provide a more accurate diagnosis, prognosis, and risk assessment.

Questions to ask your doctor

• Was my tumour tested for MYC?

• Was MYC protein overexpression or a MYC gene rearrangement found?

• How do my MYC results affect the diagnosis or prognosis?

• Were BCL2 and BCL6 tested at the same time?

• Do my MYC results influence treatment decisions?