Resection plus chemo improves survival in patients with UCR-MAC-LM

Primary tumour resection (PTR) in combination with chemotherapy (C) appears beneficial to a specific subgroup of patients with unresectable colorectal mucinous adenocarcinoma with liver metastasis (UCR-MAC-LM) compared with PTR or C alone, suggests a study.

“Therefore, we recommend PTR for eligible patients with UCR-MAC-LMs,” the authors said. “However, further prospective investigations are needed to accurately evaluate the impact of PTR+C on the survival of patients with UCR-MAC-LM, particularly in light of potential publication bias.”

Using the surveillance, epidemiology, and end results (SEER) database, the authors obtained data for patients with UCR-MAC-LM from 2010 to 2017 and then analysed clinicopathological characteristics using the χ² test. They performed propensity score matching to balance baseline characteristics.

Survival outcomes were estimated and compared using Kaplan-Meier analysis and log-rank tests. Prognostic factors were identified via univariate and multivariate Cox regression analyses.

Of the 10,178 patients with unresectable colorectal adenocarcinoma with liver metastasis included in the analysis, 612 (6.01 percent) had UCR-MAC-LM. [Am J Clin Oncol 2024;47:30-39]

Patients with UCR-MAC-LM tended to be female, older, have a higher incidence of right colon localization, larger tumour size, and higher T and N staging compared with those with unresectable colorectal nonmucinous adenocarcinoma with liver metastasis (UCR-NOS-LM; p<0.05).

Multiple independent prognostic factors associated with overall survival (OS) appeared in multivariate analysis (p<0.05). These factors included age, carcinoembryonic antigen level, tumour grade, tumour N stage, PTR, radiotherapy, and chemotherapy (p<0.05).

Survival rates were substantially greater among patients with unresectable colorectal adenocarcinoma with liver metastasis who underwent PTR+C than among those who received PTR or C alone or no treatment (cancer-specific survival (CSS): p<0.05; OS: p<0.05).

In subgroup analysis, 17 of 22 groups of patients with UCR-MAC-LM who underwent PTR+C enjoyed significantly prolonged long-term survival than those who received PTC or C alone.

Poor prognosis

Previous studies have reported the association of colorectal mucinous adenocarcinoma with a worse prognosis relative to other histologic subtypes. [Dis Colon Rectum 2003;46:160-167; J Clin Pathol 2012;65:381-388; Anticancer Res 2020;40:1651-1659]

“In our investigation, we also found that patients with UCR-MAC-LM had lower OS and CSS rates than patients with UCR-NOS-LM,” the authors said.

“Patients with UCR-MAC-LM had a higher proportion of females, advanced T and N stages, larger tumour size, and right-sided colon localization, which is consistent with previous studies,” they added. [Am Surgeon 1988;54:681-685; Ann Surg Oncol 2012;19:2814-2821; Dis Colon Rectum 2004;47:78-85; J Surg Oncol 2000;75:103-107]

“There is a lack of reliable guidelines regarding the optimal management of colorectal adenocarcinoma with liver metastasis, leading to controversy surrounding its management,” according to the authors.

The current study, though promising, had certain limitations. First, vital information on peritoneal metastasis, which is common in UCR-MAC-LM patients, was lacking in the SEER database. Second, data on the specific chemotherapeutic regimens used by patients were limited. Third, the authors did not consider appendiceal mucinous adenocarcinoma in the final patient selection.

“Consequently, future prospective randomized controlled trials are of utmost importance to corroborate these findings and explore the therapeutic potential of PTR+C in UCR-MAC-LM patients,” the authors said.