The American Society of Clinical Oncology and the College of American Pathologists (CAP) issued a joint guideline aimed at improving the accuracy of immunohistochemistry (IHC) testing for the expression status of estrogen (ER) and progesterone receptors (PgR) in breast cancer.
A news release notes that the two groups conducted a systematic review of medical research literature in partnership with Cancer Care Ontario to develop the recommendations. The guideline was published in the April 19 issues of ASCO's Journal of Clinical Oncology (JCO) and CAP's Archives of Pathology & Laboratory Medicine.
“There is clearly a need to accurately identify breast cancer subtypes as ER and/or PgR-positive to help us identify those patients most likely to benefit from endocrine therapy and minimize the risk of potentially denying effective and life-saving therapy to patients incorrectly labeled as having ER/PgR-negative invasive disease, while allowing patients with true ER/PgR-negative disease to be considered for other therapies.” said Antonio C. Wolff, MD, Co-chair of the ASCO/CAP Hormone Receptor Testing in Breast Cancer Panel and Associate Professor of Oncology at Johns Hopkins Kimmel Comprehensive Cancer Center.
The guideline recommends the following:
- Testing ER and PgR status on all newly diagnosed invasive breast cancers (primary site and/or metastatic site), and whenever appropriate, repeat testing in patients with a known breast cancer diagnosis who now present with a local or distant recurrence.
- Establishing uniform testing measures that focus on proven, reliable, and reproducible assays and procedures.
- Having testing laboratories validate their assays against existing and clinically validated tests. Results should agree at least 90% of the time with those of the clinically validated assays for positive receptor status and at least 95% for negative receptor status.
- Transporting breast tissue specimens from the operating room to the pathology laboratory as soon as they are available for gross assessment. The time from tumor removal to initiation of fixation should be kept to one hour or less. Fixation of the sample in neutral buffered formalin must extend for at least six hours and no longer than 72 hours.
- Performing ER and PgR testing in a CAP-accredited laboratory or in a laboratory that meets the accreditation requirements spelled out in the guideline. CAP will require that every accredited lab performing testing participate in a mandatory proficiency testing program.
- Considering an ER and PgR test performed by an IHC assay as positive if at least 1% of the tumor in the sample tests positive, which helps predict whether a patient is likely to benefit with endocrine treatment. The panel recognized that it is reasonable for oncologists to discuss the pros and cons of endocrine therapy with patients whose tumors contain low levels of ER by IHC (1% to 10% weakly positive cells) and to make an informed decision based on available information.
“The main goal of the ASCO/CAP ER/PgR guideline is to improve the accuracy of test results and ensure that patients receive appropriate care like endocrine therapy, as it has the potential to improve survival and save lives,” Dr. Wolff said. “Widespread access to accurate ER/PgR testing is also critical because breast cancer is the most common cause of cancer death in women in low and middle-income countries, and most of them have ER and/or PgR-positive disease.”
Elizabeth Hammond, MD, the panel's other co-chair, said, “Increased attention to simple measures such as the handling of tissue specimens from the moment they are taken from the patient to when they reach the pathologist, the uniform fixation of specimens, the standardization and validation of lab assays, rigorous reporting procedures, and greater access to treatment interventions have the potential to significantly improve breast cancer outcomes around the world.”
The ASCO/CAP Panel said it also expects that the new ER/PgR guideline will foster improved communications among cancer specialists as well as 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,” Dr. Hammond said. “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.”
In conjunction with the publishing of the guideline, ASCO and CAP also 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, which will also allow pathologists to gain special expertise in the development and implementation of these tests.