Clinicopathological and molecular features of colorectal cancer with synchronous adenoma

To investigate the clinicopathological and molecular features of colorectal cancer (CRC) with synchronous adenoma and to describe features of synchronous adenomas in CRC patients.

Single-centre retrospective cohort of 180 patients were included. The clinicopathological and endoscopic data were collected. The expression mismatch repair (MMR) proteins were detected by immunohistochemistry. The determination of microsatellite instability (MSI) was performed by multiple fluorescence PCR, and the mutations of genes were detected by real-time PCR.

Among all cases, 49 were diagnosed as CRC with synchronous adenoma, and 131 were diagnosed as solitary CRC. Some of the differences between the groups are: higher incidence was found in male (71.4 vs. 52.6%, p = .023) and in patients with habit drinking (34.7 vs. 14.5%, p = .030) and with other neoplastic diseases (42.7 vs. 26%, p = .028). Less tumors in the synchronous group were diagnosed as stage III and IV than in the solitary group (28.6 vs. 45%, p = .045). One and four mutant subtypes of KRAS gene mutations were detected insynchronous group and solitary group respectively.The prevalence of BRAF mutations in solitary group was higher than that in the synchronous group (7.4 vs. 0%, p = .045). A total of 123 adenomas were found in synchronous group and they tend to be smaller than 10 mm (74%).

Gender, a habit of drinking and other neoplastic diseases are risk factors for the development of a synchronous adenoma. With a low rate of BRAF mutations, the responses to monoclonal antibody and prognosis of patients with synchronous adenomas may be better than that of solitary CRC.