Alcohol and Formalin-Fixed Cytology Specimens Offer an Effective Alternative to Formalin-Fixed Tissue for ALK Break-Apart FISH Testing in Lung Adenocarcinoma
Frida Rosenblum, Joanne Garver, Ediz F Cosar, Lloyd Hutchinson, Elizabeth M Kurian. University of Massachusetts Medical Helathcare System, Worcester, MA
Background: For most patients with lung nodules, multiple molecular studies are often requested to determine targeted therapeutic options. In the case of crizotinib therapy, the predicted response is dependent on detection of ALK rearrangement using the gold standard fluorescence in-situ hybridization (FISH). While the current FDA guidelines require formalin fixed paraffin embedded (FFPE) tissue sections, our study validates the utility of alcohol and formalin-fixed cytology specimens.
Design: As part of our institution's (UMMHS) routine clinical practice, between November 2010 and October 2012, ALK FISH was performed on 116 lung adenocarcinoma cytology or surgical specimens. All specimens used papanicolaou stain, with integrated cytomorphology and FISH analysis, through the BioView automated Imaging system. FISH slides were scored according to the package insert. As part of the validation, 26 specimens were run in duplicate against the standard methodology carried out at reference laboratories. All slides on file (40 cytology and 38 surgical cases), were reviewed by two pathologists to assess the predominant morphologic patterns.
Results: Our cohort included 116 tumors of which 53% (62) were cytology and 47% (54) were surgical specimens. The mean age was 66 years. The 26 specimens ran in duplicate were concordant with the referral lab result. Eighteen failures were due to: (1) insufficient cells, (2) no hybridization signals, and/or (3) cancellation of the test or positivity of EGFR or KRAS. The cytology specimens included 44% (27/62) FNA's and 56% (35/62) fluids, washes and brushes. Of the surgical specimens, 57% (31/54) were biopsies. All three ALK positive cytology cases (5%, 3/62) were pleural fluids, submitted as formalin-fixed conventional cell blocks, and 2 displayed a micropapillary pattern. Of the ALK positive surgical cases (6%, 3/54), 2 showed a predominantly mucinous (67%) pattern. Failed testing in the conventional cell blocks was due mainly to lack of hybridization signals (4/19), and due to insufficient cellularity in the alcohol fixed rapid cell blocks (3/28).
Conclusions: Our study validates the utility of alcohol or formalin fixed cytology specimens for ALK FISH testing. In the new climate of cost efficient healthcare with an emphasis on less invasive procedures, ALK FISH testing on cytologic specimens may limit the need for tissue biopsy and offers invaluable therapeutic options for patients in which tissue can not be obtained.
Tuesday, March 5, 2013 1:45 PM
Proffered Papers: Section C, Tuesday Afternoon