The Value of a 21-Gene Test 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 at the University of Michigan, and the results were presented by Steven J. Katz, MD, MPH, during a health policy session at the annual meeting of the American Society of Clinical Oncology, held in Chicago, June 3-7, 2016.

This particular assay, developed by the company 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 or DCIS.

Sixty-nine percent of the 3781 women with breast cancer—from the Georgia and Los Angeles SEER registries—approached by Katz and his team, responded to the survey. Katz said that the mean age of the women who participated was older, and they had a wide distribution of age, ethnicity, and income. The women, who had been treated 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:

• Node-negative favorable (no high-risk features)
• Node-negative, less favorable (age at diagnosis less than 50 years or grade 3 tumor)
• 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 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.

Node negative, favorable (n = 718)

Node negative, unfavorable (n = 283)

Node positive,

(n = 286)

Recommended Against/neutral/for

Got chemo

Recommended Against/neutral/for

Got chemo

Recommended Against/neutral/for

Got chemo

No test (608)

54/21/25

14

25/9/66

59

9/9/82

83

RS

0-17 (427)

78/10/12

3

64/11/25

6

49/12/39

22

18-30 (204)

38/19/43

38

20/25/55

52

9/22/69

64

>30 (48)

0/0/100

100

3/5/92

94

0/0/200

100

Chemo indicates chemotherapy; RS, recurrence score.

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 more treatment, following RS score,” he said, adding that the effect was most evident in women with less favorable prognosis.

“The TAILORx and RxPONDER trials will refine the treatment algorithms further, following the test for recurrence score,” Katz said.

Reference

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).