I've been diagnosed with early-stage breast cancer. I've heard that a gene expression profiling test might help in planning my treatment. What is it?

Answers from Timothy J. Moynihan, M.D.

Gene expression profiling tests (Oncotype DX, MammaPrint, others) are used in an attempt to determine the right treatment for the right person with early-stage breast cancer. Early-stage breast cancer is cancer that may have spread to nearby lymph nodes but not to distant parts of the body. Gene expression profiling is designed to allow people who don't need additional treatment (adjuvant therapy) to avoid the side effects of unnecessary treatment, and for those who may benefit from adjuvant therapy to receive it. A gene expression profiling test analyzes the patterns of a number of different genes within the cancer cells to help predict how likely it is that an early-stage breast cancer will recur after initial treatment.

The effectiveness of gene expression profiling is still being studied in a number of clinical trials. And while some doctors are using gene expression profiling to plan treatment, others are waiting for the results of these studies. Discuss with your doctor the pros and cons of gene expression profiling. These tests are not for people with more advanced breast cancer that has spread to distant parts of the body.

There are a few gene expression profiling tests currently available. More tests are in development.

July 10, 2012