Tomomi Yamaguchi1, Toshiaki Akahane2,3, Ohi Harada1, Yasutaka Kato4, Eriko Aimono5, Hidehiro Takei6, Takashi Tasaki2, Hirotsugu Noguchi2, Hiroshi Nishihara4,5, Hajime Kamata7, Akihide Tanimoto2,3. 1. Department of Pathology, Laboratory of Cancer Medical Science, Hokuto Hospital, Obihiro, Hokkaido, Japan. 2. Department of Pathology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan. 3. Center for Human Genome and Gene Analysis, Kagoshima University Hospital, Kagoshima, Japan. 4. Department of Biology and Genetics, Laboratory of Cancer Medical Science, Hokuto Hospital, Obihiro, Hokkaido, Japan. 5. Keio Cancer Center, Keio University School of Medicine, Shinjuku-ku, Tokyo, Japan. 6. Department of Diagnostic Pathology, Asahikawa Medical University, Asahikawa, Hokkaido, Japan. 7. Department of Neurosurgery, Hokuto Hospital, Obihiro, Hokkaido, Japan.
Abstract
BACKGROUND: Cancer genome profiling of cytology specimens using next-generation sequencing (NGS) requires adequate and good-quality DNA. Genomic examination of cytology samples was conventionally performed on cell block (CB) or smear specimens than on residual liquid-based cytology (LBC) specimens, which are high-quality DNA sources even after long-term storage. METHODS: We estimated tumor fractions of 37 residual LBC specimens, including 30 fine needle aspiration (FNA) samples from the thyroid (12 papillary thyroid carcinomas and two malignant lymphomas), lymph node (13 metastatic carcinomas and one malignant lymphoma), and breast cancer (one phyllodes tumor and one invasive ductal carcinoma), two pancreatic carcinoma samples, and five liquid (ascites, pleural effusion, and cerebrospinal fluid) samples. The DNA was extracted from all samples and subjected to NGS using a customized cancer gene panel comprising 28 cancer-related genes. RESULTS: NGS analysis revealed somatic mutations corresponding to pathological diagnosis with adequate variant allele frequency (VAF) in 24 LBC specimens, which had significantly higher tumor fraction (72.5% ± 4.9%). Ten cases, including the five fluid samples, had very small tumor fractions (7.5% ± 2.3%) to obtain sufficient VAF. Other two samples had high tumor fractions but showed very low VAF, indicating the presence of fusion genes. The remaining one sample yielded no DNA recovery. CONCLUSION: The residual LBC specimens collected by FNA from the thyroid gland and lymph node were verified to carry high tumor fraction and could serve as an alternate source for molecular testing to screen and diagnose cancers without the use of CB or smears.
BACKGROUND:Cancer genome profiling of cytology specimens using next-generation sequencing (NGS) requires adequate and good-quality DNA. Genomic examination of cytology samples was conventionally performed on cell block (CB) or smear specimens than on residual liquid-based cytology (LBC) specimens, which are high-quality DNA sources even after long-term storage. METHODS: We estimated tumor fractions of 37 residual LBC specimens, including 30 fine needle aspiration (FNA) samples from the thyroid (12 papillary thyroid carcinomas and two malignant lymphomas), lymph node (13 metastatic carcinomas and one malignant lymphoma), and breast cancer (one phyllodes tumor and one invasive ductal carcinoma), two pancreatic carcinoma samples, and five liquid (ascites, pleural effusion, and cerebrospinal fluid) samples. The DNA was extracted from all samples and subjected to NGS using a customized cancer gene panel comprising 28 cancer-related genes. RESULTS: NGS analysis revealed somatic mutations corresponding to pathological diagnosis with adequate variant allele frequency (VAF) in 24 LBC specimens, which had significantly higher tumor fraction (72.5% ± 4.9%). Ten cases, including the five fluid samples, had very small tumor fractions (7.5% ± 2.3%) to obtain sufficient VAF. Other two samples had high tumor fractions but showed very low VAF, indicating the presence of fusion genes. The remaining one sample yielded no DNA recovery. CONCLUSION: The residual LBC specimens collected by FNA from the thyroid gland and lymph node were verified to carry high tumor fraction and could serve as an alternate source for molecular testing to screen and diagnose cancers without the use of CB or smears.
Authors: Dana M Hartl; Joanne Guerlain; Ingrid Breuskin; Julien Hadoux; Eric Baudin; Abir Al Ghuzlan; Marie Terroir-Cassou-Mounat; Livia Lamartina; Sophie Leboulleux Journal: Cancers (Basel) Date: 2020-11-06 Impact factor: 6.639