Differences in histological features and PD-L1 expression between sporadic microsatellite instability and Lynch-syndrome-associated disease in Japanese patients with colorectal cancer

• Published in: International journal of clinical oncology 2018-06, Vol.23 (3), p.504-513
• Main Authors: Yamada, Rin, Yamaguchi, Tatsuro, Iijima, Takeru, Wakaume, Rika, Takao, Misato, Koizumi, Koichi, Hishima, Tsunekazu, Horiguchi, Shin-ichiro
• Format: Article
• Language: English
• Subjects: Adult; Aged; Asian Continental Ancestry Group - genetics; B7-H1 Antigen - genetics; B7-H1 Antigen - metabolism; Cancer Research; CD8 antigen; Colorectal cancer; Colorectal carcinoma; Colorectal Neoplasms - genetics; Colorectal Neoplasms - pathology; Colorectal Neoplasms, Hereditary Nonpolyposis - complications; Colorectal Neoplasms, Hereditary Nonpolyposis - genetics; Confidence intervals; DNA Methylation; Female; Genetic disorders; Humans; Immunotherapy; Invasiveness; Male; Medicine; Medicine & Public Health; Microsatellite Instability; Middle Aged; Mismatch repair; MLH1 protein; Mutation; MutL Protein Homolog 1 - genetics; MutL Protein Homolog 1 - metabolism; Oncology; Original Article; PD-L1 protein; Promoter Regions, Genetic; Proto-Oncogene Proteins B-raf - genetics; Surgical Oncology; Tumors
• ISSN: 1341-9625; 1437-7772
• DOI: 10.1007/s10147-018-1238-y

Background The field of immunotherapy has recently focused on cancers with microsatellite instability (MSI). These cancers include both Lynch-syndrome-associated tumors, which are caused by mismatch repair (MMR) germline mutations, and sporadic MSI tumors, which are mainly attributed to MLH1 promoter methylation. The present study aimed to clarify differences in the histological and PD-L1 expression profiles between these two types of MSI cancers in Japanese patients. Methods Among 908 cases of colorectal cancer treated via surgical resection from 2008 to 2014, we identified 64 MSI cancers, including 36 sporadic MSI and 28 Lynch-syndrome-associated cancers, using a BRAF V600E mutation analysis and MLH1 methylation analysis. Of the latter subgroup, 21 (75%) harbored MMR germline mutations. Results The following were more frequent with sporadic MSI than with Lynch syndrome associated cancers: poor differentiation (50.0 vs. 7.1%, P  = 0.0002), especially solid type (30.6 vs. 3.6%, P  = 0.0061); medullary morphology (19.4 and 0%, P  = 0.015), Crohn-like lymphoid reaction (50.0 vs. 25.0%, P  = 0.042), and PD-L1 expression (25.0 vs. 3.6%, P  = 0.034). However, the groups did not differ in terms of the mean invasive front and intratumoral CD8-positive cell densities. In a logistic regression analysis, PD-L1 expression correlated with poor differentiation (odds ratio: 7.65, 95% confidence interval: 1.55–37.7, P  = 0.012), but not with the difference between sporadic MSI cancer and Lynch-syndrome-associated cancer (odds ratio: 4.74, 95% confidence interval: 0.50–45.0, P  = 0.176). Conclusions Therefore, compared with Lynch-syndrome-associated cancers, sporadic MSI cancers are more frequently solid, poorly differentiated medullary cancers that express PD-L1.