[2024] Duplication of Molecular Testing at a Tertiary Care Oncology Center

Melissa W Taggart, Wai-Chin Foo, Susan C Abraham. MD Anderson Cancer Center, Houston, TX

Background: Molecular testing of solid tumors is rapidly expanding due to the increased use of predictive and prognostic markers in personalized cancer therapy. In gastrointestinal (GI) carcinomas, mutation in either KRAS or BRAF genes predicts lack of response to cetuximab-based chemotherapy in second-line treatment of metastatic disease. Microsatellite instability (MSI) analysis by PCR and immunohistochemistry (IHC) can identify patients with Lynch syndrome and (arguably) identify tumors with lack of response to 5-FU but improved cancer-related survival. The widespread use of these markers in GI oncology can lead to unnecessary duplication of molecular testing when patients are referred to tertiary care centers.
Design: We reviewed all molecular tests requested by GI oncologists or oncologic surgeons for clinical/non-investigational purposes on 100 consecutive patients with colorectal or small bowel carcinomas at our cancer center during 2012. Available scanned copies of original pathology reports, outside laboratory tests, and outside and inside clinical notes were carefully reviewed to determine whether the requested tests were previously performed. In instances where testing was mentioned in the outside clinic notes but results were not documented, phone calls were placed to determine if the testing actually took place.
Results: 217 molecular tests were requested in these 100 patients, including 49 for KRAS, 36 for BRAF, 64 for MSI analysis by PCR, 65 for MSI analysis by IHC (MLH1, MSH2, MSH6 and PMS2) and 3 for MLH1 promotor methylation to help distinguish sporadic MSI-high carcinoma with MLH1 protein loss from Lynch syndrome-associated cancer. Unnecessary molecular testing was requested in 7 (14%) KRAS, 5 (14%) BRAF, 3 (5%) PCR for MSI, 9 (14%) IHC for MSI, and 1 (33%) MLH1 promotor methylation. Among this group of unnecessary requests, testing was variably: 1) already performed at an outside CLIA-certified laboratory on the same or equivalent specimen (n= 12), 2) scientifically invalid (e.g., request for BRAF analysis in a specimen known to be KRAS mutated) (n=4), or 3) requested twice for in-house testing (e.g., separate requests at different times by an oncologist or his/her physician's assistant) (n=9).
Conclusions: Given the time-consuming nature and high cost of molecular testing, duplication or unnecessary testing in 12% of GI carcinomas can significantly drive up the costs of specialized medical care. These results support the role of pathologists in screening molecular testing requests, the incorporation of outside laboratory results into pathology reports, and the push for widespread use of electronic medical records.
Category: Quality Assurance

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 282, Tuesday Morning


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