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Evidence-Based Oncology July 2016

The Value of a 21-Gene Test in Early-Stage Breast Cancer

Surabhi Dangi-Garimella, PhD
During a health policy session at the annual meeting of the American Society of Clinical Oncology, Steven J. Katz, MD, MPH, discussed the Oncotype DX Breast Cancer Assay, and it's impact on recommendations for chemotherapy in early-stage breast cancer.
Can the Oncotype DX Breast Cancer Assay, also known as the 21-gene Recurrence Score (RS) assay, impact recommendation and receipt of chemotherapy in early-stage breast cancer? Does the test also improve patient experience? These were some of the questions posed by researchers from the University of Michigan, with results presented by Steven J. Katz, MD, MPH, during a health policy session at the annual meeting of the American Society of Clinical Oncology.

This particular assay, developed by Genomic Health, is expected to predict disease recurrence and response to chemotherapy in estrogen receptor (ER)–positive, lymph node–negative early-stage breast cancer. According to the company website, the test also predicts the risk of local recurrence in those who have the more common non-invasive form of breast cancer, ductal carcinoma in-situ, commonly referred to as DCIS.

Sixty-nine percent of the 3781 women with breast cancer— from the Georgia and Los Angeles SEER registries—who were approached by Katz and his team, responded to the survey. Katz said that while the average age of the women who participated was older, they had a wide distribution of age, ethnicity, and income. The women, who had received treatment in 2013 and 2014, were asked to answer questions related to their oncologist’s treatment recommendations, chemotherapy receipt, and treatment decision satisfaction. More than 1200 patients with stage I/II, ER+, HER2- disease were categorized into 3 groups:
  1. Node-negative favorable (no high-risk features)
  2. Node-negative, less favorable (age at diagnosis less than 50 years or grade 3 tumor)
  3. Node-positive
The regression analysis conducted on this data was adjusted for comorbidity, education, income, race, location, and sampling design.1

Katz showed that in the sample of women who were evaluated, recommendations for chemotherapy and receipt of chemotherapy were both in line with their respective risk scores: a majority of those tested received a recommendation for, and subsequent chemotherapy treatment (see TABLE below). “While a majority of tested patients, about 75%, reported that the test helped decision making, yet a small percentage [25%] did not recall their test status,” Katz said.

Katz believes that the RS assay is genuinely concordant with node-negative disease, and test uptake is substantial even in patients with node-positive disease. “Patients seem to shift toward less chemotherapy, rather than altered treatment, following RS score,” he said, adding that the effect was most evident in women with less favorable prognosis.

“The TAILORx2 and RxPONDER3 trials will refine the treatment algorithms further, following the test for recurrence score,” Katz said. The Trial Assigning IndividuaLized Options for Treatment (Rx) (TAILORx) and Rx for Positive NoDe Endocrine Responsive Breast Cancer (RxPONDER) trials are examining wheth-er genes that are frequently associated with RR for women with early-stage breast cancer can be used to assign patients to the most appropriate and effective treatment. EBO
References
  1. Katz SJ, Friese CR, Li Y, et al. Clinical use of the 21-gene assay and patient experiences in early-stage breast cancer. J Clin Oncol. 2016;34 (suppl; abstract 6501).
  2. The TAILORx breast cancer trial. National Cancer Institute website. http://www.cancer. gov/types/breast/research/tailorx. Accessed June 6, 2016.
  3. RxPONDER trial: Treatment options. SWOG website. http://swog.org/Visitors/S1007/ treatment.asp. Accessed June 6, 2016.
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