Primary and Secondary Tumors

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In this month's edition of A Note From Your Doctor, Noelle LoConte, MD answers the frequently asked question about the difference between primary and secondary tumors.

In medical lingo, "primary" refers to the original site of the tumor (for example, the breast or the colon). "Secondary" refers to any additional sites where the cancer has spread (for example, the lungs or the bone).
It is not uncommon that identify metastases (or secondary tumors) from a cancer without being able to identify the "primary" or original, source. The fancy medical term for this is carcinoma of unknown primary. And although it may sound like a fancy way of saying "we don't know what this is," it is a whole diagnosis on its own, with its own clinical trial and treatment regimens.
To be given this diagnosis, a patient usually goes through a work-up to try to find the primary source, which may include things like CT scans, colonoscopies, mammograms and Pap smears, among other tests.
In addition, when the site of cancer is in the neck alone, we treat that like we do other head and neck cancers. If the disease is only in the lymph nodes (glands) under the arms, and the patient is a female, we frequently treat that as breast cancer, given that that is a common location for breast cancer to spread to.
Beyond those two sites, the treatment of carcinoma of unknown primary can include surgery, radiation or chemotherapy. The chemotherapy spreads everywhere in the body that blood spreads to, and treats both the metastases as well as the primary site (wherever that may be).

There have been a good number of clinical trials of various chemotherapy regimens for carcinoma of unknown primary, and we do have several regimens which have been shown to be effective for this disease specifically. Finally, regarding radiation, depending on the size of the radiation field, you can also treat the primary and secondary sites as well with one type of treatment modality.

About Dr. LoConte

Dr. LoConte is an assistant professor of medicine at the University of Wisconsin-Madison. She joined the faculty of the UW Carbone Cancer Center in the summer of 2006. She was the recipient of the American Society of Clinical Oncology Young Investigator Award for 2006. Her clinical interests are in gastrointestinal cancers, as well as cancer of any type in the older adult.

Dr. LoConte writes a column for Advances e-Newsletter called A Note From Your Doctor. In her column, she shares her thoughts on healthy living, cancer research and current treatments. She will even answer your questions.