Clinicopathological features and prognosis of patients with colorectal Mucinous adenocarcinoma mixed with other pathological components: a nationwide retrospective study in China.

BACKGROUND

Mucinous adenocarcinoma (MAC) is typically admixed with other pathological components, including conventional adenocarcinoma, signet ring cell carcinoma, and/or neuroendocrine neoplasms. Specifically, signet ring cell differentiation (MASD) is defined as a signet ring cell component comprising less than 50% of the tumor, and neuroendocrine differentiation (MAND) is defined as a neuroendocrine component constituting less than 30%. Furthermore, MAC admixed with conventional adenocarcinoma was defined as classic mucinous adenocarcinoma (CMAC) in this study. Therefore, the study aimed to investigate the clinicopathologic and prognostic differences between patients with CMAC and those with either MASD or MAND [collectively termed mucous adenocarcinoma mixed with other pathological components (MAM)].

METHODS

We collected data from a multi-institutional registry of patients who underwent surgical curative resection for histologically proven MAC between January 2016 and September 2021 at 22 medical institutions in China. Patients with MAC with percentage of signet ring cell ≥ 50% or percentage of neuroendocrine component ≥ 30% were excluded.

RESULTS

A total of 2023 patients from 22 medical institutions who met the study criteria were included. MAM, compared to CMAC, showed more aggressive histologic features, including higher rates of lymphovascular invasion (47.0% vs. 18.0%, p < 0.01), perineural invasion (68.0% vs. 35.1%, p < 0.01), T4 stage (33.5% vs. 26.5%, p < 0.01), N2 stage (56.2% vs. 17.8%, p < 0.01), and TNM stage III disease (73.5% vs. 49.2%, p < 0.01). MAMs had lower 3-year overall survival compared to those with CMAC (66.7% vs. 81.6%, p < 0.01). Multivariable analysis indicated that MAMs, including MASD and MAND, was an independent prognostic factor for poor disease-free survival and overall survival.

CONCLUSION

Our analysis of a large patient cohort confirmed the aggressive clinicopathological features and poor prognostic outcomes of MAM, including MAND and MASD, compared with CMAC. These findings underscore the need for surveillance protocols for MAM in clinical practice.