Shinya Takaoka1, Yosuke Hirotsu2, Hiroshi Ohyama1,3, Hitoshi Mochizuki1,4, Kenji Amemiya4, Toshio Oyama5, Hiroshi Ashizawa1, Dai Yoshimura1, Keiko Nakagomi1, Kenji Hosoda1, Yoji Suzuki1, Yuichiro Kojima1, Masao Omata1,6. 1. Department of Gastroenterology, Yamanashi Central Hospital, 1-1-1 Fujimi, Kofu, Yamanashi, Japan. 2. Genome Analysis Center, Yamanashi Central Hospital, 1-1-1 Fujimi, Kofu, Yamanashi, Japan. hirotsu-bdyu@ych.pref.yamanashi.jp. 3. Department of Gastroenterology, Graduate School of Medicine, Chiba University, Inohana, Chuo-ku, Chiba, Japan. 4. Genome Analysis Center, Yamanashi Central Hospital, 1-1-1 Fujimi, Kofu, Yamanashi, Japan. 5. Department of Pathology, Yamanashi Central Hospital, 1-1-1 Fujimi, Kofu, Yamanashi, Japan. 6. The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.
Abstract
BACKGROUND: Multiple gastric cancers at the same time (synchronous) or recurrence after 1 year (metachronous) are frequently encountered. Since their genetic profiles were not well elucidated, we molecularly subtyped the genetic events of synchronous and metachronous early-stage gastric cancers. METHODS: We studied mismatch repair (MMR) genes in 84 tumors from 31 patients (15 synchronous and 16 metachronous) by immunohistochemistry. We performed microsatellite instability analysis and targeted sequencing of 58 significantly mutated genes (SMGs) in 35 tumors from thirteen patients. Genomic data from TCGA were used for comparisons with advanced-stage cancers. RESULTS: Among the 31 patients, at least one deficient-MMR (dMMR) tumor was observed in eight (26%). Of eight patients, seven showed a mixture of proficient-MMR (pMMR) and dMMR tumors. The one case with only dMMR had six recurrent tumors within 2 years. To further subtype, we sequenced 58 SMGs in 35 samples (25 pMMR and 10 dMMR) from thirteen patients. In 35 samples, 163 mutations were identified, but none matched in almost cases, strongly indicating different clonal origins, whether synchronous or metachronous occurrences. Of the 25 pMMR cases, 1 belonged to Epstein-Barr virus (EBV), 24 belonged to chromosomal instability (CIN) subtypes. Of the thirteen cases, repetitive CIN, a mixture of CIN and MSI, a mixture of CIN and EBV, and repetitive MSI were observed in nine (70%), two (15%), one (8%) and one (8%), respectively. CONCLUSIONS: Despite multiple tumors occurring in the same patient simultaneously or several years apart, clonal origin was totally different. 'Switching' or 'mixing' of dMMR and pMMR, EBV or CIN occurred, which had clinical relevance with regard to immunotherapy.
BACKGROUND:Multiple gastric cancers at the same time (synchronous) or recurrence after 1 year (metachronous) are frequently encountered. Since their genetic profiles were not well elucidated, we molecularly subtyped the genetic events of synchronous and metachronous early-stage gastric cancers. METHODS: We studied mismatch repair (MMR) genes in 84 tumors from 31 patients (15 synchronous and 16 metachronous) by immunohistochemistry. We performed microsatellite instability analysis and targeted sequencing of 58 significantly mutated genes (SMGs) in 35 tumors from thirteen patients. Genomic data from TCGA were used for comparisons with advanced-stage cancers. RESULTS: Among the 31 patients, at least one deficient-MMR (dMMR) tumor was observed in eight (26%). Of eight patients, seven showed a mixture of proficient-MMR (pMMR) and dMMR tumors. The one case with only dMMR had six recurrent tumors within 2 years. To further subtype, we sequenced 58 SMGs in 35 samples (25 pMMR and 10 dMMR) from thirteen patients. In 35 samples, 163 mutations were identified, but none matched in almost cases, strongly indicating different clonal origins, whether synchronous or metachronous occurrences. Of the 25 pMMR cases, 1 belonged to Epstein-Barr virus (EBV), 24 belonged to chromosomal instability (CIN) subtypes. Of the thirteen cases, repetitive CIN, a mixture of CIN and MSI, a mixture of CIN and EBV, and repetitive MSI were observed in nine (70%), two (15%), one (8%) and one (8%), respectively. CONCLUSIONS: Despite multiple tumors occurring in the same patient simultaneously or several years apart, clonal origin was totally different. 'Switching' or 'mixing' of dMMR and pMMR, EBV or CIN occurred, which had clinical relevance with regard to immunotherapy.
Authors: Kai Wang; Junsuo Kan; Siu Tsan Yuen; Stephanie T Shi; Kent Man Chu; Simon Law; Tsun Leung Chan; Zhengyan Kan; Annie S Y Chan; Wai Yin Tsui; Siu Po Lee; Siu Lun Ho; Anthony K W Chan; Grace H W Cheng; Peter C Roberts; Paul A Rejto; Neil W Gibson; David J Pocalyko; Mao Mao; Jiangchun Xu; Suet Yi Leung Journal: Nat Genet Date: 2011-10-30 Impact factor: 38.330
Authors: Ahmedin Jemal; Freddie Bray; Melissa M Center; Jacques Ferlay; Elizabeth Ward; David Forman Journal: CA Cancer J Clin Date: 2011-02-04 Impact factor: 508.702