Classifying subtypes of breast cancer by a tumor's biological characteristics (tumor phenotype) can include whether or not it is hormone (estrogen or progesterone) receptor positive, human epidermal growth factor receptor 2 (HER2) positive, or "triple negative," lacking receptors for estrogen, progesterone, and HER2. The latter, HER2, plays a role in cancer cell growth and spread and identifies patients that may be considered candidates for treatment with anti-HER2 drugs in the adjuvant or metastatic settings. In 2007, ASCO and CAP issued clinical practice guideline recommendations to improve HER2 testing accuracy.
About 20 percent of all women with invasive breast cancer are HER2-positive, meaning they overexpress HER2, and about 15 percent of breast cancers do not express HER2, ER, or PgR receptors (triple-negative). Accurate determination of tumor phenotype is critical to properly select therapy options and individualize treatments.
The ASCO/CAP Panel chose to specifically focus on IHC assays for ER/PgR testing based on its widespread use, worldwide impact, and large body of evidence available. In the future, the ASCO/CAP Panel may review new methods and predictive assays to identify patients most likely to benefit from endocrine therapies as new high-level data on validated assays and outcomes become available.
The ASCO/CAP Panel also expects that the new ER/PgR guideline will foster improved communications among cancer specialists and also between patients and their doctors. Because of the availability of effective therapies for patients with hormone-receptor positive disease, the panel chairs encourage women who are told to have an ER/PgR-negative breast cancer to discuss the test result with their cancer specialists, including their oncologist and pathologist. This conversation would touch on questions like whether the hormone receptor test result is consistent with the overall pathology assessment of the tumor and whether the ER/PgR testing was done in a manner that is consistent with the new ASCO/CAP guideline.
"All medical professionals involved in cancer care want to do the right thing and offer the most correct and appropriate care to their patients. It is our hope that the ASCO/CAP ER/PgR guideline will facilitate processes at each health system and institution, so that appropriate measures to ensure accurate predictive biomarker testing (including ER/PgR) are in place and that breast cancer patients receive the highest quality care possible," said Dr. Hammond.
In conjunction with the publishing of the guideline, ASCO and CAP have developed clinical tools and resources for oncologists and pathologists that summarize the findings and recommendations. These resources include a slide presentation on ASCO's website and a guideline summary in the Journal of Oncology Practice. In addition, CAP has developed a Breast Predictive Factors Testing Certificate Program and associated Continuing Medical Education (CME), which will also allow pathologists to gain special expertise in the development and implementation of these tests.
SOURCE College of American Pathologists