Clinicopathological features and prognosis of patients with colorectal mucous adenocarcinoma mixed with other pathological components: A nationwide retrospective study in China

Background. Numerous studies have examined the clinicopathological and prognostic differences between conventional adenocarcinoma and mucinous adenocarcinoma (MAC) or adenocarcinoma mixed with other pathological components. However, the features of MAC mixed with other pathological components (MAM), including MAC with signet-ring cell differentiation (MASD) and MAC with neuroendocrine differentiation (MAND), remain unknown. This study aimed to investigate the clinicopathological features and prognosis of MAM (MAND/MASD) in comparison with classical mucinous adenocarcinoma (CMAC). 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 23 medical institutions in China. The clinicopathologic and prognostic differences between CMAC and MAM (MAND/MASD) patients were compared. Results. A total of 2,023 patients from 22 medical institutions who met the study criteria were included. MAM, compared to CMAC, showed significantly more aggressive histologic features, including higher rates of lymphovascular invasion (47.0% vs. 18.0%, p  < 0.001), perineural invasion (68.0% vs. 35.1%, p  < 0.001), T4 stage (33.5% vs. 26.5%, p  = 0.003), N2 stage (56.2% vs. 17.8%, p  < 0.001), and TNM stage III disease (73.5% vs. 49.2%, p  < 0.001). MAMs had significantly lower 3-year overall survival compared to those with CMAC (66.7% vs. 81.6%, p  < 0.001). Multivariable analysis indicated that mucinous adenocarcinoma with other pathological components, including signet-ring cell (MASD) and neuroendocrine differentiation (MAND), was an independent poor prognostic factor for 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 increased attention to MAM in clinical practice.