Oncotype Dx with an Intermediate Recurrence Score

  • The 21-gene recurrence-score assay (e.g., Oncotype DX, Genomic Health):
    • Is one of several commercially available gene-expression assays:
      • That provide prognostic information:
        • In hormone-receptor-positive breast cancer
  • The assay originally set cut points for:
    • Low risk at a recurrence score less than 18
    • Intermediate risk at 18 to 30
    • High risk at greater than 30
  • It is predictive of chemotherapy benefit:
    • When the recurrence score (RS) is high (greater than 26) and
  • It is prognostic for very low rates of distant recurrence:
    • 2% at 10 years:
      • When the RS is low (less than 10)
  • The TAILORx prospective randomized clinical trial:
    • Was completed to determine whether chemotherapy is beneficial for women with an intermediate RS of 11 to 25:
      • The cutoffs for this trial were adjusted to ensure all patients in the intermediate range who may benefit were included
    • At 9 years of follow-up:
      • The endocrine therapy only and the chemo-endocrine therapy group had similar rates of invasive disease-free survival:
        • 83.3% vs. 84.3% respectively
      • The endocrine therapy alone was noninferior to chemoendocrine therapy:
        • For all patients in the intermediate RS study group (RS 11 to 25)
      • The two groups also had similar outcomes in freedom from disease recurrence at a distant or locoregional sites:
        • However, the chemotherapy benefit for invasive disease-free survival varied with the combination of recurrence score and age (P=0.004):
          • With some benefit of chemotherapy found in women 50 years old or younger with an RS of 16 to 25:
            • In women less than 50 receiving chemotherapy:
              • Demonstrated a lower rate of distant recurrence than endocrine therapy if RS was:
                • 16 to 20 (percentage-point difference, 0.8 at 5 years and 1.6 at 9 years) or 21 to 25 (percentage-point difference, 3.2 at 5 years and 6.5 at 9 years):
                  • Overall survival however remained similar
            • For this reason, researchers conclude that the 21-gene assay can identify women with ER+ early-stage breast cancer:
              • Who may be spared chemotherapy if they are over 50 years old with an RS of 25 or lower:
                • As well as women 50 years or younger with RS of 15 or lower
  • References:
    • Sparano JA, Gray RJ, Makower DF, Pritchard K, Albain KS, Hayes DF, et al. Adjuvant chemotherapy guided by a 21-gene expression assay in breast cancer. N Engl J Med. 2018;379(2):111-121

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