Did you know that treatment for breast cancer is becoming more personalized? Some factors that help tailor treatment are related to an individual. For example, some treatments are chosen based on whether a woman is premenopausal or postmenopausal.
Most factors that help personalize treatment however, are related to the breast cancer itself. Factors such as the stage and hormone receptor status of a tumor help guide treatment. Now, we are starting to learn how the genetic makeup of a tumor may be helpful. Tumor profiling (using gene expression profiling) tools look at certain genes in a breast tumor for information that may help pick the best treatment. At this time, only a few of these tools are available and only one, Oncotype Dx®, is routinely used by health care providers in the U.S. However, this is an active area of study.
Every cell in your body has genes. Genes contain the blueprints (genetic code) for your body. For example, genes contain the information that determines the color of your eyes.
Similarly, every cell in a breast tumor has genes. These genes contain the blueprints for the tumor.
A tumor profiling test does not give genetic information about a person. Rather, it gives information about the genes in cancer cells.
When breast cancer is removed during a biopsy or surgery, the tissue is sent to a pathologist. A pathologist is a physician who studies this tissue under a microscope. If the pathologist determines the cells contain cancer, he/she also determines many characteristics about the cancer cells that guide treatment.
Some characteristics, such as the hormone receptor status and HER2/neu status of a tumor, are already widely used to help guide treatment. Researchers are now looking into how tumor characteristics at the genetic level may also help. Tumor profiling can look at thousands of genes in a tumor. Specific genes (or combinations of genes) may give information useful in making treatment decisions.
The genetic profiles of some breast tumors may help predict whether the cancer is more likely to recur (when cancer comes back) and metastasize (when cancer spreads to other organs).1
Many women are treated with chemotherapy to reduce the chances of recurrence and metastasis. Chemotherapy drugs can travel through the body and get rid of cancer cells that have spread from the breast. However, not all breast cancers will return or metastasize. So, some women are treated with chemotherapy (and endure its side effects) even when it offers them no benefit. Their breast cancers may never return, whether they are treated with chemotherapy or not. So, these women are considered “over-treated” with chemotherapy.
Knowing which tumors are most likely to recur and metastasize could help make appropriate chemotherapy decisions and avoid “over-treatment.” One goal of tumor profiling is to help identify the tumors most likely to benefit from chemotherapy.
At this time, two tumor profiling tools for breast cancer are commercially available: Oncotype Dx and MammaPrint®. These tumor profiling tests can help determine whether chemotherapy is a good treatment option for some breast cancers. They are only used for certain breast cancers though and Oncotype Dx is the only one widely used in the U.S.
Oncotype Dx tests a sample of the breast tumor (removed during a biopsy or surgery) for a group of 21 genes. Along with other factors, the results of the Oncotype Dx test can help predict the chance of metastasis for invasive breast cancers that are: 2-3
Oncotype Dx may also be used in select postmenopausal women with invasive breast cancers that are: 2-4
Although Oncotype Dx can provide some prognostic information in select premenopausal women with lymph node-positive breast cancers, it is not used to guide treatment for these women. Researchers have not yet studied whether it can help predict chemotherapy benefit for lymph node-positive premenopausal breast cancers.
MammaPrint is a tumor profiling tool that can be used for lymph node-negative breast cancers. Although FDA-approved, MammaPrint is still mostly limited to the research setting in the U.S. because it requires a special preparation of the biopsy tissue that is different from what is generally done here. MammaPrint is more commonly used in Europe.
Oncotype Dx is only used for estrogen receptor-positive cancers that will be treated with hormone therapy. It may help determine which of these breast cancers will benefit from the addition of treatment with chemotherapy.
Studies have suggested that tumors with a high Oncotype Dx score (the test shows a high risk of metastasis) may be more likely to benefit from chemotherapy than tumors with a low Oncotype Dx score (the test shows a low risk of metastasis).1,3 Chemotherapy (in addition to hormone therapy) may be advised only for tumors with high Oncotype Dx scores. Tumors that have low scores (those that are unlikely to benefit from chemotherapy) may be treated with hormone therapy alone. In this way, tumor profiling with Oncotype Dx may help some people avoid chemotherapy and its side effects.
Oncotype Dx test scores can be used to group breast cancers into a high, low or intermediate risk of metastasis. It is generally accepted that chemotherapy may be advised for breast cancers at high risk and may be avoided for those at low risk. However, the best way to treat breast cancers at intermediate risk is unclear. (Only breast cancers that are stage I or II, estrogen receptor-positive (and will be treated with hormone therapy), HER2/neu-negative and lymph node-negative are tested with Oncotype Dx. Over 40 percent of these breast cancers have an intermediate risk.)5
TAILORx (Trial Assigning IndividuaLized Options for treatment (Rx)) is a randomized clinical trial designed to learn whether tumors at intermediate risk are best treated with hormone therapy plus chemotherapy or hormone therapy alone. About 7,000 women in the U.S. and Canada were recruited into the study and assigned at random to get one of these two treatments.5 Enrollment is closed and the results of the study are not yet available.
In Europe, a study similar to TAILORx, but using MammaPrint rather than Oncotype Dx to guide treatment, is underway. MINDACT (Microarray In Node-negative and 1 to 3 positive lymph node Disease may Avoid ChemoTherapy) is a randomized clinical trial sponsored by the European Organization for Research and Treatment of Cancer.
The results of these trials may help providers better understand how these tumor profiling tests can inform treatment decisions.
PAM50 (Prediction Analysis of Microarray 50) is a promising new tumor profiling tool that looks at a set of 50 genes in estrogen receptor-positive breast cancers. This set of genes may give more information than other tests to help identity which of these cancers have the highest and the lowest risk of recurrence.6-7 PAM50 is still under study and is only available in a research setting.
Tumor profiling is a promising area in breast cancer treatment. By combining the genetic profile of a tumor with other information about the breast cancer and the individual, providers can personalize treatment plans. This helps each person get the most benefit from his/her treatment, while avoiding over-treatment (including unwanted side effects).
Although Oncotype Dx is the only gene expression profiling test commonly used in the U.S. for breast cancer, other tests are under study. As research in this area grows, so will the ability to personalize breast cancer treatment to each individual.
According to Eric Winer, MD, chief scientific advisor to Susan G Komen for the Cure®, “genomic profiling of breast cancers has come of age. More than ever before, we are able to understand how one cancer differs from another, and what makes an individual cancer, and in some cases, an individual cancer cell, grow or die. We still have much work to do, but the field has advanced by leaps and bounds in the last 10 years. Ultimately, by better understanding the underpinnings of a breast cancer, we will devise new and improved treatments.”
Clinical trials test the benefits of new treatments and diagnostic tools (like Oncotype Dx). If you are newly diagnosed with breast cancer, we encourage you to consider joining a clinical trial before starting treatment. Learn more about clinical trials.
BreastCancerTrials.org in collaboration with Susan G. Komen for the Cure® offers a custom matching service that can help you find a clinical trial that fits your health needs.
Susan G. Komen for the Cure® and 10 Affiliates have provided essential funds to support the RxPONDER (Rx for Positive Node, Endocrine Responsive breast cancer) clinical trial. RxPONDER is designed to help determine whether Oncotype Dx provides useful prognostic information for women with early breast cancers that are hormone receptor-positive, HER2-negative, and lymph node-positive.
Komen funds have paid for the initial Oncotype Dx testing of 226 women that wanted to participate in RxPONDER but were uninsured or unable to afford the cost of the test themselves.
Susan G. Komen’s Research and Scientific Programs also provide funding for numerous grants which focus on the development of tumor profiling tools as treatment decision aids. In just the past six years Komen has invested more than $60 million in over 80 grants focused on genetic tests that can help predict response to therapy and aid in treatment decisions. Current Komen-funded researchers are using tumor profiling to:
1. Paik S, Shak S, Tang G, et al. A multigene assay to predict recurrence of tamoxifen-treated, node-negative breast cancer. N Engl J Med. 30;351(27):2817-26, 2004.
2. Genomic Health, Inc. Oncotype Dx: Breast cancer assay. Redwood City, CA. http://www.oncotypedx.com/en/Breast.aspx, 2012.
3. Dowsett M, Cuzick J, Wale C, et al. for the Arimidex, Tamoxifen, Alone or in Combination (ATAC) Trialists’ Group. Prediction of risk of distant recurrence using the 21-gene recurrence score in node-negative and node-positive postmenopausal patients with breast cancer treated with anastrozole or tamoxifen: a TransATAC study. J Clin Oncol. 28(11):1829-34, 2010.
4. Albain KS, Barlow WE, Shak S, et al. for the Breast Cancer Intergroup of North America. Prognostic and predictive value of the 21-gene recurrence score assay in postmenopausal women with node-positive, oestrogen-receptor-positive breast cancer on chemotherapy: a retrospective analysis of a randomised trial. Lancet Oncol. 11(1):55-65, 2010.
5. National Cancer Institute. The TAILORx Breast Cancer Trial. http://www.cancer.gov/clinicaltrials/noteworthy-trials/tailorx, 2010.
6. Chia SK, Bramwell VH, Tu D, et al. A 50-gene intrinsic subtype classifier for prognosis and prediction of benefit from adjuvant tamoxifen. Clin Cancer Res. 18(16):4465-4472, 2012.
7. Prat A, Parker JS, Fan C, et al. Concordance among gene expression-based predictors for ER-positive breast cancer treated with adjuvant tamoxifen. Ann Oncol. 23(11):2866-73, 2012.
Updated January 8, 2013
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