Abstract
BackgroundSignet ring cell carcinoma (SRCC) is a rare subtype of colorectal cancer (CRC). The aim of this study was to characterise the genomic alterations and outcomes of SRCC.MethodsMedical records of metastatic CRC (mCRC) patients whose tumours were evaluated by NGS analysis were reviewed. SC-mCRC were classified into two groups: SRCC (>50% signet ring cells) and adenocarcinoma (AC) with SC component (≤50% signet ring cells).ResultsSix hundred and sixty-five mCRC patients were included. Of the 93 mCRC cases with SC features, 63 had slides for review. Of those 63 cases, 35 were confirmed SRCC, and 28 were AC with SC component. Compared with AC group, KRAS and PIK3CA mutations (mts) were found in only 11% (OR: 0.13) and 3% (OR: 0.15) of SRCC cases, respectively. In contrast to the 44% rate of APC mts in AC group, only 3% of SRCC patients had APC mts (OR = 0.04).ConclusionsSRCC has distinct molecular features, including low rates of KRAS, PIK3CA and APC mts. Further study to identify activation pathways and potential therapeutic targets are needed.
Highlights
Signet ring cell carcinoma (SRCC) is a rare subtype of colorectal cancer (CRC)
We reported the gene mutation frequencies in AC with signet ring cell (SC) component metastatic CRC (mCRC)
We found SRCC to be more commonly found in younger aged patients, right-sided tumour, poorly differentiated histology, more frequently with peritoneal metastasis over lung or liver metastasis and significantly inferior OS compared with non-SRCC tumours
Summary
Signet ring cell carcinoma (SRCC) is a rare subtype of colorectal cancer (CRC). The aim of this study was to characterise the genomic alterations and outcomes of SRCC. SRCC is defined by a greater than 50% presence of signet ring cells, while cases with less than or equal to 50% presence of signet ring cells are noted to have signet ring features without a formal SRCC designation.[5] In the previous studies, SRCC has been associated with younger age, advanced tumour stage at presentation and lymph node metastasis,[2,6,7,8] and SRCC has significantly poorer prognosis compared to that of adenocarcinomas.[6,9,10,11,12,13,14] Several studies have suggested a higher rate of microsatellite instability and BRAF gene mutation in SRCC.[7,15,16,17] the sample sizes in those studies were generally small, and most evaluated only single gene mutation. The aim of this study was to characterise the genomic alterations, clinicopathological characteristics and outcomes of SRCC
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