Underutilization of gene expression profiling for early-stage breast cancer in California

Cancer Causes Control. 2016 Jun;27(6):721-7. doi: 10.1007/s10552-016-0743-4. Epub 2016 Apr 20.

Abstract

Purpose: To describe the utilization of gene expression profiling (GEP) among California breast cancer patients, identify predictors of use of GEP, and evaluate how utilization of GEP influenced treatment of early-stage breast cancer.

Methods: All women diagnosed with hormone-receptor-positive, node-negative breast cancer reported to the California Cancer Registry between January 2008 and December 2010 were linked to Oncotype DX (ODX) assay results.

Results: Overall, 26.7 % of 23,789 eligible patients underwent the assay during the study period. Women age 65 or older were much less likely than women under age 50 to be tested (15.1 vs. 41.4 %, p < 0.001). Black women were slightly less likely and Asian women were slightly more likely than non-Hispanic white women to undergo GEP with the ODX assay (22.2 and 28.9 vs. 26.9 %, respectively, p < 0.001). Patients residing in low SES census tracts had the lowest use of the test (8.9 %), with the proportion increasing with higher SES category. Women with Medicaid health insurance were less likely than other women to be tested (17.7 vs. 27.5 %, p < 0.001). Receipt of adjuvant chemotherapy (ACT) was associated with the ODX recurrence score, although only 63 % of patients whose recurrence scores indicated a high benefit received ACT. Of patients not tested, 15 % received ACT.

Conclusions: Nearly three-fourths of eligible breast cancer patients in California during the 3-year period 2008 through 2010 did not undergo GEP. As a result, it is likely that many women unnecessarily received ACT and suffered associated morbidity. In addition, some high-risk women who would have benefited most from ACT were not identified.

Keywords: Breast cancer; Cancer registry; Chemotherapy; Gene expression profiling; Genomics.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • African Americans / statistics & numerical data
  • Age Factors
  • Aged
  • Asian Americans / statistics & numerical data
  • Breast Neoplasms / genetics*
  • Breast Neoplasms / pathology
  • Breast Neoplasms / therapy
  • California
  • Chemotherapy, Adjuvant
  • European Continental Ancestry Group / statistics & numerical data
  • Female
  • Gene Expression Profiling / statistics & numerical data*
  • Healthcare Disparities / ethnology
  • Healthcare Disparities / statistics & numerical data*
  • Humans
  • Mastectomy
  • Medicaid / statistics & numerical data
  • Middle Aged
  • Neoplasm Recurrence, Local*
  • Neoplasm Staging
  • Registries*
  • Risk
  • Social Class*
  • United States