Miso Kim, Hyo Sup Shim, Sheehyun Kim, In Hee Lee, Jihun Kim, Shinkyo Yoon, Hyung-Don Kim, Inkeun Park, Jae Ho Jeong, Changhoon Yoo, Jaekyung Cheon, In-Ho Kim, Jieun Lee, Sook Hee Hong, Sehhoon Park, Hyun Ae Jung, Jin Won Kim, Han Jo Kim, Yongjun Cha, Sun Min Lim, Han Sang Kim, Choong-Kun Lee, Jee Hung Kim, Sang Hoon Chun, Jina Yun, So Yeon Park, Hye Seung Lee, Yong Mee Cho, Soo Jeong Nam, Kiyong Na, Sun Och Yoon, Ahwon Lee, Kee-Taek Jang, Hongseok Yun, Sungyoung Lee, Jee Hyun Kim, Wan-Seop Kim
J Pathol Transl Med. 2024;58(4):147-164. Published online January 10, 2024
In recent years, next-generation sequencing (NGS)–based genetic testing has become crucial in cancer care. While its primary objective is to identify actionable genetic alterations to guide treatment decisions, its scope has broadened to encompass aiding in pathological diagnosis and exploring resistance mechanisms. With the ongoing expansion in NGS application and reliance, a compelling necessity arises for expert consensus on its application in solid cancers. To address this demand, the forthcoming recommendations not only provide pragmatic guidance for the clinical use of NGS but also systematically classify actionable genes based on specific cancer types. Additionally, these recommendations will incorporate expert perspectives on crucial biomarkers, ensuring informed decisions regarding circulating tumor DNA panel testing.
Background Homologous recombination defect is an important biomarker of chemotherapy in certain tumor types, and the presence of pathogenic or likely pathogenic mutations involving BRCA1 or BRCA2 (p-BRCA) mutations is the most well-established marker for the homologous recombination defect. Gastric cancer, one of the most prevalent tumor types in Asia, also harbors p-BRCA mutations.
Methods To investigate the clinical significance of p-BRCA mutations, we analyzed 366 gastric cancer cases through next-generation sequencing. We determined the zygosity of p-BRCA mutations based on the calculated tumor purity through variant allelic fraction patterns and investigated whether the presence of p-BRCA mutations is associated with platinum-based chemotherapy and a certain molecular subtype.
Results Biallelic p-BRCA mutation was associated with better response to platinum-based chemotherapy than heterozygous p-BRCA mutation or wild type BRCA genes. The biallelic p-BRCA mutations was observed only in the chromosomal instability subtype, while all p-BRCA mutations were heterozygous in microsatellite instability subtype.
Conclusions In conclusion, patients with gastric cancer harboring biallelic p-BRCA mutations were associated with a good initial response to platinum-based chemotherapy and those tumors were exclusively chromosomal instability subtype. Further investigation for potential association with homologous recombination defect is warranted.
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