Tufts Medical Center Department of Pathology and Laboratory Medicine is the headquarters for a new international consortium of accreditation agencies and academic pathologists in the recently launched Consortium for Analytic Standardization of Immunohistochemistry (CASI). The consortium will establish industry-wide immunohistochemistry (IHC) reference standards to improve test accuracy and reproducibility. The announcement was recently published online in Archives of Pathology & Laboratory Medicine.
CASI is initially funded by a $2 million grant from the National Cancer Institute. Its mission is to integrate analytic reference standards into IHC, a test format widely used in surgical pathology to evaluate cancers in tissue samples and determine correct treatment.
Clinical laboratory practices in IHC differ from practices in other types of hospital laboratories, such as the blood testing laboratory. Standard patient blood tests can be analyzed in any lab and yield the same results every time because of international reference standards that ensure all tests are aligned with one another; both patient and physician can have confidence in the results whenever the tests are performed.
No such reference standards exist in IHC, meaning that different labs can – and often do – return different results from the same sample. Rates of clinically inadequate IHC testing are roughly 10 times that of clinical blood testing labs, with test discrepancy rates of 10 to 30 percent.
“The absence of analytic standards is a highly unusual situation for a clinical diagnostic testing environment,” according to the paper. “There is no precedent . . . for an entire clinical laboratory testing industry to lack analytic standards, especially one so large, well established, and critically important for patient care as IHC.”
CASI will conduct studies to determine appropriate analytic sensitivity thresholds for selected IHC tests, publish the data it collects, and then offer analytic sensitivity recommendations. In addition to guiding routine clinical practice, these recommendations will be intended to facilitate and simplify methodology transfer between laboratories, from published literature, and in clinical trials.
“Physicians rely on IHC companion diagnostic results to inform diagnosis and treatment decisions for their cancer patients. However, without reference standards, pathologists lack the necessary tools to ensure accurate, consistent results,” said Keith Miller FIBMS, former director of the UK National External Quality Assessment Scheme for Immunohistochemistry, a CASI steering committee member. “CASI was formed to fill this critical void in surgical pathology by establishing the standards and controls that make more reliable test results possible.”
“CASI’s technical mission – to identify objective, quantifiable analytic sensitivity guidelines for IHC assays – has an important patient impact,” said Dr. Steve Bogen, the head of CASI and a clinical pathologist in the Tufts Medical Center Department of Pathology & Laboratory Medicine. “The standards of clinical laboratory practice that CASI creates stands to provide oncologists greater confidence in diagnosing patients and selecting the proper course of treatment, reduce the need for re-testing in laboratories, and inform accurate patient selecting during clinical trials.”