Your body has the capability to produce tumors that can be either benign (non-cancerous) or malignant (cancerous). Scientists have long believed that tumors develop from a single cell that can multiply and mutate (change) at an accelerated rate. These mutated cells either remain in their original location, or they can spread to other parts of the body. These two different locations are the basis of primary and secondary tumors.

Primary Tumors

When we look at the growth of cancerous cells in the human body, the location in which a tumor begins growing is known as the primary site. This means that a primary tumor is where cancer first begins to grow in the body. Even if this tumor grows extremely fast or spreads, some signs and symptoms can help diagnose where cancer started.

All benign tumors are considered to be primary. This is because they do not invade surrounding tissues or spread to other parts of the body. There are many different primary tumors, but some of the most common are adenomas, fibromas or fibroids, lipomas, and nevi (moles).

In very rare cases, the primary location of growth cannot be determined. It is estimated that only 3-5% of all cancerous tumors have an unknown origin in which typical diagnostic tests fail to identify the location of the primary tumor.

Secondary Tumors

A secondary tumor is one that starts in one part of the body as a primary tumor and then spreads to at least one other location. The medical term that is used for these types of secondary tumors is known as metastases. When a small tissue sample (biopsy) is taken from a secondary tumor, it is possible to determine the location of the primary tumor location. This is because the secondary tumor will contain cells from the original (primary) location.

For example, if a person is diagnosed with a secondary tumor in the brain, the biopsy of the tumor may show that the primary location was in the breast tissue, lungs, or even skin. This tells the doctor that at some point in time, a small amount of the cells from the primary tumor broke off and traveled through the blood or lymph and implanted in the secondary location. These cancerous cells then continued to grow in the new area, forming a secondary tumor.

A benign primary tumor may pose little or no health problems. A primary malignant tumor, however, can be severe. The severity of a malignant tumor also depends on the location of the primary tumor and how quickly it can spread and form a secondary tumor (metastasize). If you or a loved one finds a lump that you suspect could be a tumor, schedule an appointment with your primary doctor. Early diagnosis of a tumor can identify what type it is and provide prompt treatment if necessary.

References

Ciftdemir, M., Kaya, M., Selcuk, E., & Yalniz, E. (2016). Tumors of the spine. World Journal of Orthopedics, 7(2), 109-116. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4757655/

National Cancer Institute (n.d.). Metastatic Cancer. Retrieved from https://www.cancer.gov/types/metastatic-cancer

Søndergaard, D., Nielsen, S., Pedersen, C. N., & Besenbacher, S. (2017). Prediction of primary tumors in cancers of unknown primary. Journal of Integrative Bioinformatics, 14(2). https://www.ncbi.nlm.nih.gov/pubmed/28686574