[1867] EGFR Mutation Analysis: What's Being Tested? The Experience of a Single Academic Medical Center.

Laura J Tafe, Mary C Schwab, Joel A Lefferts, Carol Hart, Candice C Black, Vincent A Memoli, Vijayalakshmi Padmanabhan, Gregory J Tsongalis. Dartmouth-Hitchcock Medical Center, Lebanon, NH

Background: Testing for EGFR mutations is an important tool to guide molecularly targeted therapy in patients with pulmonary non-small cell carcinoma (NSCLC). Diagnostic molecular pathology laboratories receive specimens for EGFR mutation analysis from a variety of sources. In this study, we review our experience with the types and appropriateness of specimens submitted to us for EGFR mutation testing.
Design: A database was created to record information on the specimens submitted to our molecular pathology laboratory during the 15 month interval that we have offered EGFR mutation analysis as a clinical test. Information recorded included specimen preparation (i.e. fresh/formalin fixed), type of specimen (i.e. FNA, core biopsy, excision), clinical status of tested tumor (i.e. primary, metastasis, recurrence) and the diagnosis of the primary tumor with site of origin. All in house specimens were reviewed by a pathologist for adequacy of material for testing.
Results: From May 2009 to August 2010, our laboratory evaluated 242 specimens for EGFR mutation status. Twenty-two (9%) were submitted by outside institutions, 75 (31%) by cytology and 145 (60%) by surgical pathology. Overall, only 4 cases did not have sufficient DNA to complete the analysis. Of the 238 evaluable cases, 216 were formalin-fixed paraffin-embedded (FFPE) and 22 were fresh frozen. Most specimens were surgical resection/excisions (98, 41%) and core biopsies (94, 39%) followed by FNA cell blocks (30, 13%); others included pleural fluids, sputum and washes. The primary tumor was most frequently tested (149, 63%) followed by metastases (75, 32%) and rarely recurrent and second primaries. As expected, the overwhelming majority of tumors were diagnosed as adenocarcinoma or poorly differentiated/NOS NSCLC (208 and 12 respectively). However, 3 squamous cell carcinomas and 1 large cell neuroendocrine carcinoma of lung were also tested. Interestingly, 9 cases of metastatic carcinoma of other known primary and 5 cases of metastatic carcinoma of unknown primary were submitted. In total, 4 were insufficient for genotyping, 24 were positive for an EGFR mutation and 214 were non-mutated.
Conclusions: Overall, our clinicians and pathologists are submitting samples appropriate for EGFR mutation analysis that can be successfully evaluated. Rarely, the test is probably ordered inappropriately in instances where a known carcinoma other than NSCLC is the diagnosis. Our study also shows that at times physicians are using EGFR mutation analysis to aid in the diagnosis and possibly treatment of a carcinoma of unknown primary.
Category: Quality Assurance

Monday, February 28, 2011 1:00 PM

Poster Session II # 230, Monday Afternoon


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