The Utility of Cytologic Specimens for Molecular Testing, Our Experience in a Cancer Center
S Billah, M Guo. UT MD Anderson Cancer Center, Houston, TX
Background: With increased targeted treatment for cancer patients, PCR-based molecular testing to determine the eligibility for the treatment has been significantly increased in our hospital. However, the experience of using cytologic specimens for molecular testing is limited. We retrospectively reviewed the cytology cases with molecular testing in order to determine the utility of cytologic specimens for the testing.
Design: A total of 130 molecular tests using cytologic specimens from 62 patients were retrieved from the Department of Pathology at M.D. Anderson Cancer Center from June to August in 2009. The patients included 26 males and 36 females with an age-range from 37 to 87 years old and an average age of 63 years. The cytologic preparations, i.e., cell blocks vs. smears, were compared with the specimen adequacy and DNA extraction sufficiency for molecular testing.
Results: In 62 patients, lung cancer (31 cases) was the most frequent primary carcinoma, followed by colon (5 cases), breast (3 cases), pancreas (2 cases) and ovary carcinoma (1 case). Other malignancies include melanoma (8 cases) and lymphoma (5 cases). EGFR was the most frequently tested biomarker (41) followed by K-ras (40), BRAF (14), PIK3CA (8), C-Kit (8) and N-ras (6). Specimens consisted of 56 cases of FNA, 5 cases of pleural fluid and 1 case of peritoneal fluid. In cytologic specimens used for molecular testing, cell block material accounted for 76% (47/62), while smears accounted for 24% (15/62). Insufficient material for molecular testing was determined in 9 cases, 6 cases (13%, 6/47) from cell block material and 3 cases (20%, 3/15) from smears. Six cases had insufficient DNA for molecular testing, 3 cases (6%, 3/47) from cell block material and 3 cases (20%, 3/15) from smears. The combined insufficiency rates for molecular testing were 19% (9/47) in cell block material and 40% (6/15) in smears, respectively.
Conclusions: Cytologic material can be used for molecular testing to guide targeted treatment in cancer patients. Cell block material was used more frequently and had lower insufficient rate for molecular testing compared with smears. Our findings suggested the importance of obtaining sufficient cytology sample for cell block preparation if molecular testing is anticipated.
Wednesday, March 24, 2010 1:00 PM
Poster Session VI # 70, Wednesday Afternoon