Repeating Breast Cancer Prognostic and Predictive Markers.
Sara Bakhtary, Kristin C Jensen. Stanford University Medical Center, CA; Palo Alto Veterans Health Care System, Palo Alto, CA
Background: Estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) are important prognostic factors in breast cancer and impact clinical decisions regarding adjuvant systemic therapy. Prior to the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) Recommendations published in January 2007, it was estimated that approximately 20% of HER2 testing may be inaccurate. The publication outlined validation procedures, quality assurance, and proficiency testing requirements for CAP-accredited laboratories performing HER2 testing beginning in 2007 to improve accuracy. Similar guidelines have been proposed for ER and PR testing. Despite testing standardization, breast cancer predictive markers are sometimes performed on initial core biopsies and then repeated on the resection specimen.
Design: Breast cancer cases with predictive marker testing from January 2007 to August 2010 were reviewed. Of these 1233 cases, 226 had ER, PR, and/or HER2 repeat testing. All predictive marker test values, dates of testing, and status of neoadjuvant therapy were recorded. Also noted was whether testing was performed at an outside institution, and whether those studies were reviewed at Stanford.
Results: Of the 226 cases with testing on more than one specimen, overall repeat test agreement was 96% for ER (211/220), 90% for PR (197/220), and 94% for HER2 (205/217). Fifty-one cases (23%) were ER/PR negative on initial testing with 8% change in status at retest. Fifty-six cases (25%) were initially performed and then repeated at Stanford with 9% status change at retest. Seventy-six cases (34%) were initially performed at an outside institution and not reviewed at Stanford with 13% status change at retest. Eighty-six cases (38%) were initially performed elsewhere and reviewed at Stanford with 19% status change at retest.
Conclusions: Since the establishment of guidelines by ASCO/CAP in January 2007, less than 10% of breast cancer cases have had a status change in predictive marker results, suggesting that widespread test and report standardization has been effective. At least some of these changes could be attributed to sampling at the time of core biopsy and interpretation of stains. Considerations for repeat testing include delayed treatment and increased health care cost.
Monday, February 28, 2011 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 26, Monday Morning