Touch Imprint Cytology in Tumor Tissue Banks for the Confirmation of Neoplastic Cellularity and for DNA Extraction

Abstract

Learning the characteristics of frozen tissue samples stored in tumor banks for biological studies remains a problem. To assess the use of touch imprint cytology on fresh tissue samples as a rapid and reliable method of determining the presence and quantity of neoplastic cells before freezing. Touch imprint cytology was performed on 259 specimens of operable breast cancer. Touch imprints were prepared from fresh tissue specimens before freezing samples for storage. Each tumor sample was imprinted on a glass slide and stained with hematoxylin-eosin. Tumor cellularity was quantified as negative, poor, moderate, or rich. A significant correlation was found between samples with a tumor size greater than 2 cm and high tumor cellularity (P = .03; chi(2) test). Furthermore, 35% of ductal tumors showed higher tumor cellularity compared with lobular tumors (P < .001; chi(2) test). No association was found between lymph node status and tumor grade. When samples for which more than 2 imprints were available were examined, tumor cellularity among imprints of the same sample showed an overall agreement of 0.67 (P < .001; kappa statistic). It was also determined that the higher the cellularity, the higher the agreement. Our data also showed concordance of 0.87 (P < .001; kappa statistic) between touch imprint cytology imprints and histologic sections from contiguous tumor. Moreover, 11 randomly selected samples underwent DNA extraction, polymerase chain reaction, and sequencing to verify the feasibility of DNA analyses. We found that DNA from touch imprint cytology was amplifiable and suitable for direct sequencing. Touch imprint cytology may represent an important step in the quality control of tumor cellularity of breast cancer specimens designed to be stored in tumor biobanks and a valid method for assessing the suitability of such tissue for further biomorphologic and biomolecular applications.