Research into the causes, diagnosis, and treatment of cancer is being done at many cancer research centers. Scientists are making progress in understanding how changes in a person's DNA can cause normal cells to develop into cancer. A greater understanding of the gene changes that can occur in cancer is providing insight into why these cells become abnormal. Some of these advances may lead to better diagnosis and treatment of cancers of unknown primary (CUPs).

Diagnosis

It is very important that doctors are able to identify the origin of cancers of unknown primary so that the most effective treatments can be used. Immunohistochemistry and other lab tests can be very helpful in this regard, but they are not yet able to tell where all CUPs have started. Newer lab tests now becoming available will help classify CUP more precisely and predict a patient's prognosis and response to treatment.

Some of the most promising tests perform what is called gene expression profiling on a tumor sample. Instead of looking for changes in a single gene or protein, these tests look at patterns of many genes at the same time to see which ones are turned on or off. This pattern is then compared with the patterns of genes in known types of cancer to see if they match. Several different gene expression profile tests are now available. While they can help narrow down the cancer type to help guide doctors, they are not yet able to tell which type of cancer it is with certainty.

But these tests will continue to get more accurate. Hopefully at some point in the future, the number of cancers of unknown primary will drop dramatically, as doctors will be able to test tumor samples and determine what types of cancer they are.

Treatment

Because CUP represents a number of different types of cancer, it is unlikely that a single treatment breakthrough will benefit all people with CUP. Still, progress in treating some of the more common types of cancer is likely to benefit people with CUP as well, especially if the cancers can be classified more accurately.

Some newer drugs called targeted therapies are being studied. These drugs have more selective effects than chemotherapy. Some of these, such as bevacizumab (Avastin) and erlotinib (Tarceva), are available to treat other cancers and have shown some activity in CUP. Clinical trials are in progress to help determine who may benefit from targeted drugs and what drugs and combinations are best.

Many patients with cancer of unknown primary face a serious prognosis, so the need for advances in treatment is obvious. Clinical trials of new treatments are essential if progress is to occur. Some of these trials are testing new chemotherapy drugs, new drug combinations, and new ways to give these drugs. Other clinical trials are studying new approaches to treatment, such as biological therapy, immunotherapy, and gene therapy. Because CUP is a very diverse category of many types of cancers, progress against CUP is likely to depend on continued progress toward understanding the molecular basis of all cancers.

Last Medical Review: 10/15/2009
Last Revised: 10/15/2009