Two national cancer organizations recently updated their guidelines and recommendations for breast cancer testing to include a multiparameter gene expression test. The American Society of Clinical Oncology (ASCO), a professional organization that represents members from several oncology disciplines, and the National Comprehensive Cancer Network (NCCN), a national organization consisting of 21 cancer centers across the U.S., each released revised guidelines within the last few months. New to both sets of guidelines is the recommended use of a multi-gene test to predict the risk of breast cancer recurrence and the effectiveness of certain therapies in specific populations of breast cancer patients.

The test, Oncotype DX, is a molecular assay that looks at a panel of 21 genes in a sample of tumor tissue removed during a biopsy. The new recommendations regarding the use of this test apply specifically to patients with early breast cancer that has not spread to lymph nodes (node-negative) and whose tumor has tested positive for estrogen receptors (ER-positive). Testing cancerous breast tissue for receptors to hormones is often part of an initial workup of breast cancer and helps to determine treatment options. Patients with tumors that are ER-positive (tumors whose growth is stimulated by estrogen) are often treated with the anti-estrogen drug tamoxifen. However, not all ER-positive tumors show good response to tamoxifen.

Oncotype DX, say the guidelines, has been shown to improve the ability to predict whether a patient will benefit from tamoxifen therapy. This test can be used to identify patients at high or low risk of recurrence and may help determine which patients will receive the most benefit from tamoxifen therapy alone and who could possibly forego treatment with chemotherapy. The recommendations also pointed out that patients whose results from this test suggest a high risk of recurrence may benefit most from standard chemotherapy (CMF) rather than from tamoxifen.

The 2008 version of NCCN’s Clinical Practice Guidelines in Oncology includes Oncotype DX in the decision tree that is intended to help guide patients and their health care providers through various treatment options. ASCO’s 2007 Update of Recommendations for the Use of Tumor Markers in Breast Cancer, released in November of 2007, does not include a specific place in the decision tree for the use of this test but suggests that Oncotype DX may be considered for use in newly diagnosed patients with node-negative, estrogen-receptor positive breast cancer.

Not enough is known yet, say the ASCO comments, to determine whether results from Oncotype DX can be applied to hormone therapies other than tamoxifen or chemotherapies other than CMF. The clinical utility of gene expression assays such as Oncotype DX continues to be evaluated. A large, prospective, randomized clinical trial, the Trial Assigning Individualized Options for Treatment (TAILORx), is ongoing and may provide additional information in the future to further assist patients and their doctors with decisions about approaches to treating their breast cancer.

Sources

S1
(24 Jan 2008) NCCN Updates Breast Cancer Guidelines. Medical News Today (online article). Available online at http://www.medicalnewstoday.com/articles/94979.php.

S2
National Comprehensive Cancer Network Practice Guidelines in Oncology. Breast Cancer v.2.2008.

S3
(November 20, 2007). Harris L, et al. American Society of Clinical Oncology 2007 Update of Recommendations for the Use of Tumor Markers in Breast Cancer. Journal of Clinical Oncology Vol 25, No 33, 2007: pp. 5287-5312. Available online at http://jco.ascopubs.org/cgi/content/full/25/33/5287