Mucinous Adenocarcinoma as a High-risk Factor in Stage II Colorectal Cancer: A Propensity Score-matched Study from Japan

Abstract

Background/Aim: The purpose of this study was to investigate the clinical, pathological, and prognostic differences between adenocarcinoma (ADC) and mucinous adenocarcinoma (MUC) in colorectal cancer (CRC). Patients and Methods: This was a retrospective study of a Japanese high-volume cancer Center over a 10-year period. From April 2007 to December 2016, a total of 3,296 patients with primary CRC were included in the study. The clinical characteristics of MUC and ADC were compared. Then, propensity score matching was performed according to a 1:2 ratio. Multivariate analysis was used for independent risk factors related to prognosis. The overall survival (OS) and disease-free survival (DFS) of 126 cases of MUC and 256 cases of ADC were studied, as well as the survival rate of each stage. Results: MUC accounts for 3.82% of the total CRC. Compared to ADC, MUC is more common in female patients (47.62% vs. 38.77%; p=0.045), with higher carcinoembryonic antigen levels (56.35% vs. 34.95%; p<0.001), more ulcerative and infiltrative types (82.54% vs. 72.93%; p=0.016), higher incidence of perineural infiltration (51.59% vs. 41.04%; p=0.018), deeper infiltration (T3-T4: 90.48% vs. 65.84%; p<0.001), and more advanced cancer (stage III-IV: 59.52% vs. 44.79%; p=0.001). MUC is also more likely to recur (24.6% vs. 14.32%; p=0.001). Regarding the long-term survival rate, the OS (p<0.001) and DFS (p=0.05) is consequently worse. After propensity score matching, multivariate analysis showed that MUC was a common independent risk factor for DFS [odds ratio (OR)=4.277; 95% confidence interval (CI), 0.327-0.97; p=0.039], and also for OS (OR= 6.836; 95% CI, p=0.009). In MUC, OS and DFS were still relatively worse (OS: p=0.017; DFS: p=0.038). However, only significant statistical differences were shown in stage II (OS: p=0.003; DFS: p=0.007). No significant differences were noted in the stages I, III, or IV. Conclusion: MUC is a high-risk factor for stage II CRC. Adjuvant chemotherapy should be routinely recommended for patients with MUC stage II, and special attention should be paid during their follow-up.According to European and American guidelines, patients with a high risk of recurrence after radical surgery for stage II colorectal cancer (CRC) should receive adjuvant chemotherapy (1, 2). However, the definition of "high risk" varies. Mucinous adenocarcinoma (MUC) is defined as a high-risk factor in United States guidelines, but not in European guidelines. In Japan, clinical trials of conventional postoperative adjuvant chemotherapy for stage II CRC have not been found to be successful (3). In 2019, there are few Japanese guidelines for the treatment of stage II rectal cancer using adjuvant chemotherapy (4). There are also different opinions on whether or not adjuvant chemotherapy is required for patients with postoperative stage II MUC.MUC is a rare tumor classification of CRC. This type of tumor contains neoplastic cells that produce a large amount of extracellular mucin. Histological markers require more than 50% of the tumor...

Risk Factors for Recurrence of Radically Resected Mucinous Colorectal Adenocarcinoma

“…Previous studies showed that MAC is more frequently found in female patients and is predominantly located in the proximal colon. [27][28][29] Our data showed that 42.59% patients were right colonic MA, which is consistent with previous studies. However, there was one major difference compared to prior work that our data showed the proportion of female patients (53.09%) was not dominant.…”

Risk factors for recurrence of radically resected mucinous colorectal adenocarcinoma

“…Consistent with other studies, our data showed that the incidence rate of MAC is 5.24%. Previous studies showed that MAC is more frequently found in female patients and is predominantly located in the proximal colon [22][23][24]. Our data showed that 42.59% patients had right colonic MA, consistent with previous studies.…”

“…The clinicopathological signi cance of a mucinous CRC subtype is well appreciated but remains controversial. Some studies have shown that MA has a worse prognosis than non-mucinous adenocarcinoma [23,[29][30][31], whereas others have shown no prognostic difference compared to conventional CRC [32,33]. Although there was no direct comparison with non-mucinous adenocarcinoma in the present study, compared with previous published data [11,34], the 5-year OS rate of this group (67.3%) of mucinous adenocarcinoma was lower.…”

Clinicopathological characteristics, molecular alterations and prognosis of mucinous histology in colorectal adenocarcinoma patients

“…Despite several studies comparing underlying clinicopathological differences between MAC and conventional CRC. Still, controversial results relating prognostic value of mucinous histology have been reported [2][3][4][5][6][7]. Till present, the prognostic value of MAC remains undetermined when the locations of the tumor, molecular alterations, population characteristics or different treatment plans are taken into account.…”