Cancer is named from the place it originates. This makes a difference on what type of treatments will be effective. Being diagnosed with cancer of the unknown primary (CUP) means that cancer has been found in the body but the place of origin is unknown.

If later, the place of origin is found then the type of cancer diagnosis changes from an unknown primary to the specific organ or body area that the disease first began.

Some cases of cancer of the unknown primary are unfortunately never found. Physicians will then decide on the best course of treatment based on two factors: The way the cells look under the microscope and which organs are currently involved.

Statistics and Prognosis:

The exact number of cases of this disease is not known. It may be about 2% to 5% of all cancers in the United States. It is found more often among men than among women. The average age of people with this cancer is about 60 years.

This is a very dangerous cancer. Only half of patients will live 9 to 12 months after their cancer is found. There are several reasons why this cancer is so serious. First, most of these are fast-spreading cancers. Second, because the exact type is not known, it is harder for doctors to know what treatment is best. Also, the cancer is often widespread, making it harder to cure.

In recent years, microscopic and other diagnostic techniques have improved dramatically. For this reason, doctors can now determine the primary site in about four out of five cases.

Cancer of the unknown primary is when cancer is found somewhere in the body but the pathologist is unable to tell where the cells originated from. The cancer cells are so poorly differentiated that they do not resemble any cells of the body. It can be very difficult to find the right treatment because doctors usually use the type of cancer as the main starting point to choose chemotherapy or treatments that are known to be effective. Other problems arise with this type of diagnoses. Many physicians do not have much to go on to treat this disease or know if the patient is likely to survive.

French researchers have developed a prognostic model for cancer of the unknown primary. The findings were published in the December 1st issue of Cancer. Low serum albumin levels and elevated serum lactate dehydrogenase (LDH) in the blood of patients had the worse prognosis overall. This prognostic model can show who has the most powerful adverse prognostic factors.

Even with this information though, it doesn't seem to have anything to do with treatment. They can tell who has a better or worse prognosis but what then?

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Cancer of the unknown primary