Modern Treatment of Rectal Cancer Closes the Gap Between Common Adenocarcinoma and Mucinous Carcinoma

Should the Baseline MRI Staging Criteria Differentiate Between Mucinous and Classical Rectal Adenocarcinoma?

RATIONALE AND OBJECTIVES

To compare baseline MR imaging features for pre-treatment staging between rectal mucinous adenocarcinoma (RMAC) and rectal classical adenocarcinoma (RCAC), and to investigate whether the subtype of mucinous carcinoma influences MRI evaluation criteria and high-risk tumors identifying.

METHODS

A total of 306 patients who underwent surgical rectal cancer resection were retrospectively reviewed in the study. MR imaging parameters of the primary tumor and lymph nodes (LNs) were compared between two subtypes. Logistic regression and receiver operating characteristic analyses were performed to test significant associations between LN imaging parameters and malignant LN status in RMAC and RCAC, respectively.

RESULTS

The length of mucinous tumors was larger than RCAC tumors in pT3 and pT4 stage. For pN0 patients, the long and short diameters of the largest LN on MRI were more likely to be larger in RCAC than RMAC. For pN+ patients, the proportion of LNs exhibiting internal heterogeneity in RMAC was obviously greater than that in RCAC. The best cut-off value of the largest short diameter of malignant LNs was 6.05 mm for RMAC and 8.05 mm for RCAC. And the highest AUC for predicting LNs metastases based on the largest short diameter was 0.794 for RMAC using 6 mm size cut-off, and 0.667 for RCAC using 8 mm cut-off.

CONCLUSION

The imaging features that were associated with LN metastases were different between RMAC and RCAC, and different size criteria of LNs was suggested to distinguish high-risk tumors. Clinicians should stay vigilant of LN status and take histologic subtypes into consideration before assigning clinical strategies.

Mucinous Degeneration on MRI After Neoadjuvant Therapy in Patients With Rectal Adenocarcinoma: Frequency and Association With Clinical Outcomes

BACKGROUND. Patients with nonmucinous rectal adenocarcinoma may develop mucinous changes after neoadjuvant chemoradiotherapy, which are described as mucinous degeneration. The finding's significance in earlier studies has varied. OBJECTIVE. The purpose of this study was to assess the frequency of mucinous degeneration on MRI after neoadjuvant therapy for rectal adenocarcinoma and to compare outcomes among patients with nonmucinous tumor, mucinous tumor, and mucinous degeneration on MRI. METHODS. This retrospective study included 201 patients (83 women, 118 men; mean age, 61.8 ± 2.2 [SD] years) with rectal adenocarcinoma who underwent neoadjuvant chemoradiotherapy followed by total mesorectal excision from October 2011 to November 2015, underwent baseline and restaging rectal MRI examinations, and had at least 2 years of follow-up. Two radiologists independently evaluated MRI examinations for mucin content, which was defined as T2 hyperintensity in the tumor or tumor bed, and resolved differences by consensus. Patients were classified into three groups on the basis of mucin status: those with nonmucinous tumor (≤ 50% mucin content on baseline and restaging examinations), those with mucinous tumor (> 50% mucin content on baseline and restaging examinations), and those with mucinous degeneration (≤ 50% mucin content on baseline examination and > 50% content on restaging examination). The three groups were compared. RESULTS. Interreader agreement for mucin content, expressed as a kappa coefficient, was 0.893 on baseline MRI and 0.890 on restaging MRI. Of the 201 patients, 156 (77.6%) had nonmucinous tumor, 34 (16.9%) had mucinous tumor, and 11 (5.5%) had mucinous degeneration. Mucin status was not significantly associated with complete pathologic response (p = .41) or local or distant recurrence (both p > .05). The death rate during follow-up was not significantly different (p = .21) between patients with nonmucinous tumor (23.1%), those with mucinous tumor (29.4%), and those with mucinous degeneration (9.1%). In adjusted Cox regression analysis, with mucinous degeneration used as reference, the HR for the overall survival rate for the mucinous tumor group was 4.7 (95% CI, 0.6-38.3; p = .14), and that for the nonmucinous tumor group was 8.0 (95% CI, 0.9-59.9; p = .06). On histopathologic assessment, all 11 patients with mucinous degeneration showed acellular mucin, yet 10 of 11 patients showed viable tumor (i.e., in nonmucinous portions of the tumors). CONCLUSION. Mucinous degeneration on MRI is not significantly associated with pathologic complete response, recurrence, or survival. CLINICAL IMPACT. Mucinous degeneration on MRI is uncommon and should not be deemed an indicator of pathologic complete response.

Long-term effect of neoadjuvant radiotherapy in patients with locally advanced rectal mucinous adenocarcinoma: a population-based study of 1514 patients

Rectal mucinous adenocarcinoma (RMAC) is a rare and aggressive form of rectal cancer. The effectiveness of neoadjuvant radiotherapy (NRT) for RMAC has not been well studied, and the survival benefit remains controversial. The purpose of this work was to determine the prognostic role of NRT in patients with RMAC by propensity-score matching (PSM). A retrospective cohort study using the Surveillance, Epidemiology, and End Results from 2004 to 2015 was performed. In the multivariate analysis before PSM, NRT provided better OS (HR 0.61, 95% CI 0.52-0.71, p < 0.001) and CSS (HR 0.68, 95% CI 0.56-0.82, p < 0.001). Multivariate analysis after PSM (n = 844) confirmed that patients receiving NRT survived longer than those without NRT (OS: HR 0.60, 95% CI 0.50-0.78, p < 0.001 and CSS: HR 0.68, 95% CI 0.54-0.84, p < 0.001). Subgroup analysis indicated that NRT had significantly improved OS and CSS in stage II RMAC and OS in stage III RMAC after adjusting for various confounding factors.

The prognostic ability of radiotherapy of different colorectal cancer histological subtypes and tumor sites

The prognostic significance of radiotherapy (RT) for colorectal cancer (CRC) has shown conflicting results, particularly among different pathological subtypes, including adenocarcinoma (AC), mucinous adenocarcinoma (MC), and signet-ring cell carcinoma (SR). This study analyzed the prognosis of three pathological CRC types and focused on the prognostic significance of RT on three CRC histological subtypes. Patients diagnosed with AC (n = 54,174), MC (n = 3813), and SR (n = 664) in the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database (2010-2017) were evaluated. Cox regression models and competitive risk models were built to assess the effect of RT on the risk of CRC-associated death. Potential interactions between RT and stratified variables including age, sex, and tumor location were examined by multiplicative models. Compared with AC patients, SR patients had the worst overall survival (OS) among 3 subtypes of CRC (log-rank test, p < 0.001). Compared with patients who did not receive radiotherapy, RT was associated with a 1.09-fold (HR = 1.09, 95%[CI]: 1.03, 1.15) elevated risk of death among AC patients. In the SR group, RT significantly reduced the risk of death by 39% (HR = 0.61, 95%[CI]: 0.39-0.95). However, RT did not appear to independently influence survival in the MC group (HR = 0.96, 95%[CI]: 0.77, 1.21). In the subgroup analysis, tumor location (colon and rectum) significantly modified the association between RT and the risk of death among the AC and SR patients (p for interaction < 0.05). SR patients exhibited a worse OS (overall survival) than AC patients, and the effect of RT varied according to CRC histological subtypes. This can ultimately lead to more personalized and effective treatment strategies for CRC patients.

Prognosis of mucinous colon cancer is determined by histological biomarkers rather than microsatellite instability

The prognostic value of microsatellite instability (MSI), as well as other histological characteristics such as lymphovascular invasion (LI), perineural invasion (PNI) and extramural vascular invasion (EMVI), is unclear in colorectal mucinous carcinoma (MC). This study aims to determine the relevance of these factors in MC patients and analyses the role of MSI in stage III MC patients treated with adjuvant chemotherapy. A cohort of 650 patients diagnosed with stages I-IV colonic MC from 2000 to 2010 was selected from PALGA, the nationwide Dutch pathology databank. Histopathology was revised and mismatch repair (MMR) status determined. Univariate and multivariate survival analyses were performed. Deficient MMR (dMMR) was found in 33% of MCs and correlated with female gender and right-sidedness, but also with lower tumour stage (stages I/II: 73.2 versus 47%; P < 0.0001) and the absence of EMVI (9.7 versus 23.7%; P < 0.0001) and PNI (5.6 versus 12.7%; P = 0.005). On univariate analysis OS was better for dMMR MC than for proficient MMR (pMMR) MC (median OS of 9.7 versus 5.0 years; P = 0.009), but MMR status was no longer a relevant prognostic factor on multivariate analysis [hazard ratio (HR) = 0.91, 95% confidence interval (CI) = 0.70-1.18]. Stage III MC patients benefited from adjuvant chemotherapy, and dMMR status was associated with better OS in this group (HR = 0.35, 95% CI = 0.13-0.94). EMVI, LI and PNI, but not MMR, status are independent prognostic factors for survival in MC patients. Stage III MC patients benefit from adjuvant chemotherapy and dMMR status is associated with improved survival when adjuvant chemotherapy is given.

Locally advanced rectal mucinous adenocarcinoma: is preoperative radiation necessary?

BACKGROUND

Neoadjuvant chemoradiotherapy is recommended for locally advanced rectal cancer, allowing preoperative down-staging of the primary tumor to facilitate complete surgical removal. However, further investigation is warranted for identifying whether radiotherapy is necessary for rectal mucinous adenocarcinoma (RMAC). Thus, this study was designed to explore the relationship between mFOLFOX6 with or without preoperative radiotherapy and therapeutic efficacy in locally advanced RMAC.

METHODS

A total of 81 patients were retrospectively enrolled, with MRI-defined clinical stage II/III RMAC received neoadjuvant treatment with mFOLFOX6 alone (group A) or mFOLFOX6 plus radiation (group B), followed by total mesorectal excision. Tumor down-staging and tumor response were assessed based on post-treatment MRI-defined radiographical and pathological findings. Follow-up data were retrieved, and the Kaplan-Meier curve was used to determine the relationship between the 3-year disease-free survival (DFS) and overall survival (OS) in the two groups.

RESULTS

There were no significant differences in the clinical baseline characteristics of patients between group A and group B. The sphincter preservation rate in group B was 60.9%, higher than in group A (20.0%) (P=0.031). The rate of pathological complete response (pCR) was 14.0% in group B, while no patients had pCR in group A (P=0.029), and the tumor response rate in group B was higher than in group A (52.0% vs. 16.1%, P=0.001). The 3-year probability of OS in group A and B was 77.4% and 72.0% (P=0.509), and 3-year DFS was 58.1% and 56.0% (P=0.592), respectively.

CONCLUSIONS

Neoadjuvant mFOLFOX6-based chemoradiotherapy could be a promising therapeutic option for patients with RMAC, which was associated with a high rate of pCR and sphincter preservation in comparison to treated with mFOLFOX6 alone.

An Analysis of Clinicopathological Outcomes and the Utility of Preoperative MRI for Patients Undergoing Resection of Mucinous and Non-Mucinous Colorectal Cancer Liver Metastases

Background and Aims

Mucinous colorectal cancer has traditionally been associated with high rates of recurrence and poor long-term survival. There is limited published data on outcomes for patients undergoing liver resection for metastatic mucinous colorectal cancer. The aim of this study was to compare the clinicopathological outcomes for patients with mucinous colorectal cancer liver metastases (CRCLM) undergoing liver resection to a matched group of patients with adenocarcinoma not otherwise specified (NOS) and to evaluate the accurary of preoperative magnetic resonance imaging (MRI) at detecting the presence of mucin in liver metastases.

Materials and Methods

Patients with mucinous CRCLM undergoing liver resection were matched 1:3 to patients with adenocarcinoma NOS CRCLM. Clinicopathological data from the primary tumour and metastatic lesion were collected and compared between the groups. Hepatic recurrence-free, disease-free and overall survival were compared between the groups. The ability of preoperative MRI to detect mucin in CRCLM was also evaluated.

Results

A total of 25 patients with mucinous CRCLM underwent surgery over the 12-year period and were matched to 75 patients with adenocarcinoma NOS. Clinicopathological findings were similar between the groups. Resection of mucinous CRCLM was feasible and safe with similar levels of morbidity to adenocarcinoma NOS. There were no differences identified in hepatic recurrence-free (p=0.85), disease-free (p=0.25) and overall survival (p=0.98) between the groups. MRI had a sensitivity of 31.3% in detecting the presence of mucin in CRCLM.

Conclusion

Patients with mucinous CRCLM in this study had similar outcomes to patients with adenocarcinoma NOS. Based on our findings, histological subtype should not be taken into account when deciding on resectability of CRCLM.

Construction of Novel Prognostic Nomogram for Mucinous and Signet Ring Cell Colorectal Cancer Patients with a Survival Longer Than 5 Years

Purpose

Patients and Methods

Results

Conclusion

Identification of proteins associated with treatment response of neoadjuvant chemoradiotherapy in rectal mucinous adenocarcinoma by co-expression network analysis based on proteomic analysis

For rectal mucinous adenocarcinoma (MAC), identifying biomarkers of neoadjuvant chemoradiotherapy (NCRT) response has become imperative. This study applied label-free mass spectrometry and weighted gene co-expression network analysis to identify hub proteins in association with the NCRT response in 20 rectal MAC patients. We identified 131 differentially abundant proteins and 7 candidate proteins associated with the NCRT response. The immunostaining expressions of six proteins (ENOA, ILEU, MDHM, RM11, PTGDS, and RL3) were significantly associated with the NCRT response. Logistic regression analysis revealed that ENOA (OR = 6.275, P = 0.006) was independent risk hub protein for the NCRT response. Tow hub proteins (ENOA and PTGDS) were identified as significant risk factors by Cox regression analysis. A prognostic risk score system was constructed: risk score = (0.910 × EXP_ENOA) + (-1.519 × EXP_PTGDS), and found to be an independent predictor of DFS in rectal MAC patients (HR = 10.308, P < 0.001). Our study suggested that ENOA may be a novel biomarker for the NCRT response and prognosis in rectal MAC patients. A two-hub-protein-based risk score system might be used for predicting tumor recurrence in rectal MAC patients. SIGNIFICANCE: NCRT resistance is a major problem in the treatment of rectal MAC patients. Identifying robust predictive biomarkers for NCRT resistance is beneficial to the stratified treatment of rectal MAC patients. In this study, label-free mass spectrometry and weighted gene co-expression network analysis identified ENOA as a potential novel biomarker for the NCRT response and prognosis. ENOA may be involved in the process of the NCRT resistance and tumor recurrence through the carbon metabolism pathway.

OUP accepted manuscript

Purpose

Methods

Results

Conclusion

Mucinous adenocarcinoma: A unique clinicopathological subtype in colorectal cancer

Mucinous adenocarcinoma (MAC) is a unique clinicopathological subtype of colorectal cancer, which is characterized by extracellular mucinous components that comprise at least 50% of the tumor tissue. The clinical characteristics, molecular features, response to chemo-/radiotherapy, and prognosis of MAC are different from that of non-MAC (NMAC). MAC is more common in the proximal colon, with larger volume, higher T-stage, a higher proportion of positive lymph nodes, poorer tumor differentiation, and a higher proportion of peritoneal implants compared to NMAC. Although biopsy is the main diagnostic method for MAC, magnetic resonance imaging is superior in accuracy, especially for rectal carcinoma. The aberrant expression of mucins, including MUC1, MUC2 and MUC5AC, is a notable feature of MAC, which may be related to tumor invasion, metastasis, inhibition of apoptosis, and chemo-/radiotherapy resistance. The genetic origin of MAC is mainly related to BRAF mutation, microsatellite instability, and the CpG island methylator phenotype pathway. In addition, the poor prognosis of rectal MAC has been confirmed by various studies, and that of colonic MAC is still controversial. In this review, we summarize the epidemiology, clinicopathological characteristics, molecular features, methods of diagnosis, and treatments of MAC in order to provide references for further fundamental and clinical research.

Poor response at restaging MRI and high incomplete resection rates of locally advanced mucinous rectal cancer after chemoradiation therapy

AIM

Mucinous carcinoma is a histological subtype of rectal cancer and has been associated with a poor response to neoadjuvant chemoradiotherapy (CRT). The primary aim of this study was to analyse the response on MRI of mucinous locally advanced rectal cancer (LARC) after CRT compared to regular adenocarcinoma.

METHOD

Patients with LARC (defined as cT4 and/or cN2), who underwent CRT followed by restaging MRI and surgery in two tertiary referral hospitals were retrospectively included in the study. Pre- and post-treatment MRI was reviewed by an experienced abdominal radiologist.

RESULTS

A total of 102 patients, of whom 29 were diagnosed with mucinous carcinoma, were included for analysis. At restaging MRI, adenocarcinoma patients demonstrated significantly less clinical involvement of the mesorectal fascia (37% vs. 62%, P = 0.003) while this was not demonstrated in mucinous carcinoma patients (86% vs. 97%, P = 0.16). Significant downstaging after CRT in adenocarcinoma patients (P = 0.01) was seen while, in mucinous carcinoma patients, no downstaging after CRT (P = 0.89) was seen. Pathology revealed significantly higher rates of an involved circumferential resection margin in mucinous carcinoma versus adenocarcinoma patients (27.6% vs. 1.4%; P < 0.001). After multivariate regression analysis, mucinous carcinoma remained an independent prognostic factor for local recurrence (hazard ratio 3.6; 95% CI 1.1-12.4), although no differences in overall or disease-free survival were observed.

CONCLUSION

Mucinous rectal carcinoma is associated with a poor clinical response at restaging MRI after CRT, leading to relatively higher rates of involved circumferential resection margins at pathology. In this cohort, mucinous carcinoma seems to be a prognostic factor for increased risk of local recurrence, without an effect on overall survival.

Mucinous Adenocarcinoma Predicts Poor Response and Prognosis in Patients With Locally Advanced Rectal Cancer: A Pooled Analysis of Individual Participant Data From 3 Prospective Studies

PURPOSE

To evaluate the predictive implications and prognosis of mucinous adenocarcinoma (MAC) in locally advanced rectal cancer (LARC) with intensified neoadjuvant treatment.

METHODS

Individual patient data of LARC patients from 3 prospective clinical trials was analyzed. Neoadjuvant treatment regimens comprised chemoradiotherapy (CRT) with fluorouracil (5-FU) or mFOLFOX6, neoadjuvant chemotherapy alone with mFOLFOX6 or mFOLFOXIRI. The postoperative pathological result, local recurrence and disease-free survival (DFS) were retrospectively analyzed in patients with MAC and adenocarcinoma (AC) with neoadjuvant treatment.

RESULTS

Totally, 743 patients were recruited, with 620 patients eligible for analysis. Fifty-three (8.5%) patients were MAC. The pathological complete response (pCR) rate and tumor downstaging rate (ypStage 0-I) between MAC and AC patients was 7.5% vs. 22.0% (P = .01) and 20.8% vs. 48.7% (P < .001), respectively. Among patients receiving preoperative CRT with 5FU or mFOLFOX6, the pCR rate and tumor downstaging rate between MAC and AC patients was 11.1% vs. 27.3% (P = .03) and 23.7% vs. 52.6% (P = .001), respectively. Regarding neoadjuvant chemotherapy alone with mFOLFOX6 or mFOLFOXIRI, the pCR rate and tumor downstaging rate was 0 vs.13.2% (P = .11) and 11.8% vs. 42.5% (P = .03) between MAC and AC group, respectively. With the median follow-up time of 38.9 months, the 3-year DFS and 3-year locoregional recurrence rate was 58.4% vs. 77.6% (P = .02) and 26.0% vs. 5.7% (P = .001) in the MAC and AC group, respectively. MAC (hazard ratio [HR] 1.85, 95% confidence interval [CI], 1.15-2.98), PNI (HR 3.23, 95% CI, 1.85-5.72) and LVI (HR 2.04, 95% CI, 1.02-4.08) were independent prognosis factors and were associated with worse DFS.

CONCLUSIONS

Patients with MAC of the rectum are associated with a lower pCR rate and tumor downstaging rate, higher incidence of local recurrence, and poorer DFS with neoadjuvant treatment.

Risk Factors for Recurrence of Radically Resected Mucinous Colorectal Adenocarcinoma

Background

Mucinous adenocarcinoma (MA) is a subtype of colorectal cancer (CRC) associated with a higher incidence of local extension and worse survival compared to non-mucinous adenocarcinoma, but few studies have investigated surgery-related predictors for recurrence of MA. Therefore, we aimed to elucidate the predictors for local recurrence and remote metastasis of MA after surgery.

Patients and Methods

This study retrospectively analyzed 162 patients with mucinous colorectal adenocarcinoma (MAC) after radical resection. Analysis variables included demographics, clinical indicators, pathologic stage, surgical procedure, adjuvant therapy, and recurrence. Univariate and multivariate analyses were performed to investigate the risk factors for local and distant tumor relapse.

Results

A total of 162 patients (86 male) with a mean age of 58.26 years were included; 70.37% of patients had colonic tumors, and 29.63% had rectal tumors. The 5-year disease-free survival (DFS) rates for these patients were as follows: 100% for TNM stage I, 71.2% for stage II, and 47.8% for stage III. Five-year DFS rates of MAC, colonic and rectal MA were 62.0%, 65.8%, and 51.7%, respectively. Local recurrence occurred in 38 patients and distant metastasis in 33 patients. In univariate analysis, predictors for local recurrence of MAC were intraoperative blood loss, intraoperative transfusion, and N2 stage; and predictors for distant metastasis were male sex, CA199, CEA, intraoperative blood loss, T4 stage, and N2 stage. In multivariate analysis, predictors for local recurrence of MAC were intraoperative transfusion (P=0.04, OR=4.175) and N2 stage (P=0.000, OR=5.291), and predictors for distant metastasis were male sex (P=0.049, OR=2.410), CA199 (P=0.02, OR=1.003), and T4 stage (P=0.007, OR=4.006).

Conclusion

Intraoperative transfusion and N2 stage were significant predictors for local recurrence. Male sex, CA199, and T4 stage were significant predictors for distant metastasis. Knowledge of the risk factors for postoperative recurrence provides a basis for logical approaches to treatment and follow-up of MAC.

Resistance to Cell Death in Mucinous Colorectal Cancer-A Review

Mucinous colorectal cancer (CRC) is estimated to occur in approximately 10-15% of CRC cases and is characterized by abundant extracellular mucin. Mucinous CRC is frequently associated with resistance to apoptosis. Inferior prognosis is observed in mucinous CRC, particularly in rectal cancer and metastatic cases. Mucins are heavily glycosylated secretory or transmembrane proteins that participate in protection of the colonic epithelium. MUC2 overexpression is a hallmark of mucinous CRCs. Mucinous CRC is associated with KRAS and BRAF mutation, microsatellite instability and the CpG island methylator phenotype. Mutations of the APC gene and p53 mutations which are characteristic non-mucinous colorectal adenocarcinoma are less common in mucinous CRC. Both physical and anti-apoptotic properties of mucin provide mechanisms for resistance to cell death. Mucin glycoproteins are associated with decreased expression of pro-apoptotic proteins, increased expression of anti-apoptotic proteins and increased cell survival signaling. The role for BCL-2 proteins, including BCL-X_L, in preventing apoptosis in mucinous CRC has been explored to a limited extent. Additional mechanisms opposing cell death include altered death receptor expression and altered mutation rates in genes responsible for chemotherapy resistance. The roles of alternate cell death programs including necroptosis and pyroptosis are not well understood in mucinous CRC. While the presence of MUC2 is associated with an immunosuppressive environment, the tumor immune environment of mucinous CRC and the role of immune-mediated tumor cell death likewise require further investigation. Improved understanding of cell death mechanisms in mucinous CRC may allow modification of currently used regimens and facilitate targeted treatment.

Mucinous and Non-Mucinous Rectal Adenocarcinoma-Differences in Treatment Response to Preoperative Radiotherapy

There is a need to personalize the treatment for rectal cancer patients. The aim of this study was to analyze therapy response and prognosis after preoperative radiotherapy in rectal cancer patients with mucinous adenocarcinoma compared to those with non-mucinous adenocarcinoma. The study included retrospectively collected data from 433 patients, diagnosed with rectal cancer in the South East health care region in Sweden between 2004 and 2012. Patients with non-mucinous adenocarcinoma that received short-course radiotherapy before surgery had better overall survival, cancer specific survival, and disease-free survival, as well as distant- and local-recurrence-free survival (p = 0.003, p = 0.001, p = 0.002, p = 0.002, and p = 0.033, respectively) compared to the patients that received long-course radiotherapy with concomitant capecitabine. The results were still significant after adjusting for sex, age, stage, differentiation, and chemotherapy in the neoadjuvant and/or adjuvant setting, except for local-recurrence-free survival that was trending towards significance (p = 0.070). In patients with mucinous adenocarcinoma, no difference in survival was seen when comparing patients that had short-course radiotherapy and patients that had long-course radiotherapy. However, none of 18 patients with mucinous adenocarcinoma treated with long-course radiotherapy had local tumor progression, compared to 7% of 67 patients with non-mucinous adenocarcinoma. The results indicate that mucinous adenocarcinoma and non-mucinous adenocarcinoma may respond differently to radiotherapy.

Outcomes of Laparoscopic Surgery for Mucinous Colorectal Adenocarcinoma

Background: Mucinous colorectal adenocarcinoma (MAC) has a higher incidence of local extension, leading to lower overall resection rates. Few studies have investigated the outcomes of laparoscopic surgery for MACs to date. Therefore, we aimed to elucidate the validity of laparoscopic surgery for mucinous adenocarcinoma (MAC). Methods: This study analyzed short-term and long-term outcomes between laparoscopic and open surgery for MACs from 2008 to 2018. Multivariate analyses were used to define prognostic factors of overall survival (OS) and disease-free survival (DFS). Results: Patients in the laparoscopy (LAP) group had significantly less blood loss, fewer days to first flatus and to diet, and shorter length of hospital stay. The 3-year and 5-year DFS rates for all stages combined were 65.7% and 62.5% in the LAP group compared with 60.5% and 57.6% in the open (OPEN) surgery group (P = .521). The 3-year and 5-year OS rates for all stages combined were 72.3% and 67.3% in the LAP group compared with 72.6% and 67.8% in the OPEN group (P = .934). OS and DFS in stage II, stage III, and pathological T4 (pT4) stage patients who underwent laparoscopic surgery did not differ from patients who underwent open surgery. Multivariate analysis showed that stage pT4, pN2, and carcinoembryonic antigen (CEA) were significant predictors of OS. Independent factors, including intraoperative blood transfusion, stage pT4, pN2, CEA, and CA19-9, carbohydrate antigen 19-9, have a great effect on DFS. Conclusions: Laparoscopic surgery is a safe and feasible option for mucinous colorectal AC, which provides faster postoperative recovery and less intraoperative blood loss.

Application of liver acquisition with volume acceleration enhanced sequence in improving the accuracy of reassessing organ-invasive rectal mucinous adenocarcinoma after chemoradiation

OBJECTIVES

To explore the ability of liver acquisition with volume acceleration contrast-enhanced sequence (LAVA-ce) to improve the accuracy of reassessing adjacent organ involvement by rectal mucinous adenocarcinoma (MC) after neoadjuvant therapy (NAT).

METHODS

This study retrospectively enrolled twenty-five patients with MC who underwent pre- and post-NAT MRI, were staged as T4b using pre-NAT T₂ weighted imaging, received NAT and underwent radical resection. All MR images were divided into two schemes, T₂ weighted plus diffusion weighted imaging (T₂D_w protocol) and plus LAVA-ce (T₂D_wL_ce protocol). All patients were scored on a 0-4 scale to reassess organ-invasive mucus components. Postoperative pathology was used to identify the involvement of surrounding organs (ypT4b). The receiver operating characteristic (ROC) curve and area under the curve (AUC) were used to evaluate the consistency of the results with pathology after adding fs-CE sequence.

RESULTS

Among 25 MC patients (15 males and 10 females, aged 21-89 years), 21 were restaged as yT4b after NAT by using T₂D_w, with an accuracy of 44.0 % (11/25), which was lower than the accuracy of staging patients with non-mucinous rectal adenocarcinoma (94.1 %, 96/102). The accuracy of MC restaging was improved by using T₂D_wL_ce (23/25). The AUC of T₂D_wL_ce was 0.857 (95 % CI, 0.660∼0.964), which was higher than that of T₂D_w (AUC, 0.611 [95 % CI, 0.397∼0.798]) (P = 0.019).

CONCLUSION

The LAVA-ce sequence can improve the accuracy of reevaluation and should be included in the MRI protocol for MC patients.

A New MRI-Defined Biomarker for Rectal Mucinous Adenocarcinoma: Mucin Pool Patterns in Determining the Efficacy of Neoadjuvant Therapy

Background and Aim: This work aims to study the relationship between MRI-defined mucin pool (MP) patterns prior to treatment and the efficacy of neoadjuvant therapy (NAT) in locally advanced rectal mucinous adenocarcinoma (RMAC).

Methods: This retrospective study included 278 RMAC patients evaluated between January 2012 and January 2019. After having been trained by using 118 cases with postoperative pathological images, radiologists distinguished MRI-defined MP status as mixed type (MTMP) and separate type (STMP) in a NAT cohort (160 patients) in addition to tumor characteristics, invasion of mesorectal facia, and nodal status. Reader reproducibility was determined using the κ coefficient. The main outcome was the accuracy of MP dichotomy in predicting whether patients had tumor responsiveness or not.

Results: Among 278 cases, MTMP and STMP accounted for 49.6 and 50.4% of MPs, respectively. A total of 72 patients received neoadjuvant chemoradiotherapy and 88 received chemotherapy. The tumor responsiveness rate in the chemoradiotherapy group was higher than that in the chemotherapy group (58.3 vs. 21.6%, P < 0.001). In the chemotherapy group, the tumor responsiveness rate in patients with MTMPs was lower than that in patients with STMPs (4.9 vs. 25.5%, P = 0.002). The baseline MRI-defined MTMP was associated with lower responsiveness rates after NAT in the chemotherapy group (odds ratio, 11.050, with 95% CI, 2.368–51.571, P = 0.002).

Conclusions: MP dichotomy can be reliably evaluated by using MRI. In the chemotherapy group, MTMP may be a dependent predictor to indicate a lower likelihood of tumor responsiveness after NAT.

Predictive Significance of Mucinous Histology on Pathologic Complete Response Rate Following Capecitabine-Based Neoadjuvant Chemoradiation in Rectal Cancer: a Comparative Study

INTRODUCTION

Currently, neoadjuvant fluoropyrimidine-based chemoradiation followed by surgery is considered the standard of care for locally advanced rectal cancer. The current study aimed to investigate the predictive significance of mucinous histology on the pathologic complete response rate following neoadjuvant chemoradiation in locally advanced rectal cancer and to propose potential new treatment protocol for this specific histology.

MATERIAL AND METHOD

This retrospective study was conducted on 403 patients with locally advanced (clinically T3-4 and/or N1-2) rectal adenocarcinoma who had been treated at three tertiary academic hospitals between 2010 and 2015. Among those 403 patients, 46 (11%) had mucinous rectal cancer (MRC) and 358 (89%) had non-mucinous rectal cancer (NMRC). All patients underwent neoadjuvant chemoradiation with capecitabine followed by low anterior or abdominoperineal resection.

RESULTS

There were 268 men and 135 women with a median age of 55 years (range, 26-82 years). Patients with MRC were younger (p = 0.002) and presented with a larger tumor size (p < 0.001) and a more advanced tumor stage (p = 0.033) compared to the ones with MNRC. In the univariate analysis, female gender (p = 0.009), distal tumor location (p = 0.035), higher tumor stage (p = 0.049), node positivity (p = 0.001), MRC histology (p = 0.017), and high pretreatment CEA level (p = 0.013) were observed to be predictive of a poor pathologic complete response. However, in the multivariate analysis, tumor stage was the single most predictive factor of response to neoadjuvant chemoradiation.

CONCLUSION

Mucinous adenocarcinoma is a significant predictive factor for poor pathologic complete response to neoadjuvant capecitabine-based chemoradiation in patients with locally advanced rectal cancer. New treatment modality based on biomarkers may be considered in future prospective studies because of MRC poor prognosis. Immunotherapy combined with chemotherapy and/or radiotherapy may be an attractive option because of the tumor microsatellite instability-high status.

An inflammation index-based prediction of treatment response to neoadjuvant chemoradiotherapy for rectal mucinous adenocarcinoma

OBJECTIVE

This study aimed to evaluate the predictive value of hematological inflammation-based indexes in the treatment response to neoadjuvant chemoradiotherapy (NCRT) in rectal mucinous adenocarcinomas (MACs).

METHODS

Patients with rectal MACs undergoing NCRT and curative resection were included. Inflammation-based indexes such as systemic immune-inflammation index (SII), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and prognostic nutritional index (PNI) were calculated. Receiver operator characteristics analysis was used to determine the optimal cutoff points. Multivariable logistic analysis identified predictors of good response to NCRT. A nomogram was developed and validated internally.

RESULTS

A total of 100 patients met the inclusion criteria, with 32 patients developing good response (tumor regression grade, TRG 0 + 1) to NCRT. Lower pre-treatment SII, NLR, and PLR levels were associated with a higher probability of good response to NCRT (P = 0.025, P < 0.001, P = 0.003, respectively), and a higher pre-treatment PNI level was associated with a higher probability of good response to NCRT (P = 0.005). Logistic regression analysis demonstrated that tumor size (< 3 cm, OR = 5.489, P = 0.025), pre-treatment NLR level (< 3.05, OR = 4.025, P = 0.028), pre-treatment PLR level (< 145.98, OR = 4.337, P = 0.038), and pre-treatment PNI level (≥ 41.32, OR = 3.477, P = 0.039) were independent predictors of good response to NCRT. A nomogram was developed with a C-index of 0.827.

CONCLUSION

Hematological inflammation-based indexes, in terms of pre-treatment NLR, PLR, and PNI levels, can help in predicting the treatment response to NCRT for rectal MACs.

Clinicopathological characteristics and prognosis of colorectal mucinous adenocarcinoma and nonmucinous adenocarcinoma: a surveillance, epidemiology, and end results (SEER) population-based study

BACKGROUND

Mucinous adenocarcinoma (MC) is a rare histological subtype of colorectal adenocarcinoma. Previous studies investigating the prognosis of MC have conflicting results and the proper treatment of MC remains unclear.

METHODS

This retrospective study presents the clinicopathological characteristics and prognosis of MC. This cohort study collected data from April 1 through August 01, 2018. This study used data on 107,735 patients with nonmucinous adenocarcinoma (NMC) and 9,494 with MC between 2009 and 2013 from the Surveillance, Epidemiology, and End Results program (SEER). Clinicopathological features were analyzed by chi-square test and survival curves by the Kaplan-Meier method. We used propensity score matching (PSM) to account for potential bias. Logistic regression and Cox proportional hazards models were used to compare and calculate adjusted risks of MC death.

RESULTS

MC was more frequent in patients with older age, large tumor size and moderate tumor grade compared with NMC (P<0.001). Five-year survival was lower for MC patients than NMC patients (P<0.001). Older age, later tumor node metastasis (TNM) stage and multiple tumors indicated a poorer prognosis while surgery gave better survival outcomes [hazard ratio (HR) =0.38; 95% confidence interval (CI), 0.33 to 0.44; P<0.001]. Younger age, left-side colon location and early disease stage were associated with better survival after surgery (P<0.001).

CONCLUSIONS

Age, TNM stage, tumor number and treatment were indicators of prognosis and surgery gave better survival for MC patients compared with those without surgery. Our study contributes to their clinical treatment.

Prognostic impact of preoperative immunonutritional status in rectal mucinous adenocarcinoma

Aim: To explore the impact of preoperative the albumin-to-globulin ratio (AGR) and the prognostic nutritional index (PNI) on prognosis in rectal mucinous adenocarcinoma (MAC). Methods: A total of 128 patients were included. Results: According to the X-tile analysis, cutoff values of AGR and PNI were 1.1 and 43.8. Preoperative AGR (p = 0.041), preoperative PNI (p = 0.036) and pTNM stage (p = 0.003) were independently associated with overall survival in rectal MAC patients. Distance from the anal verge (p = 0.005), preoperative AGR (p = 0.021), preoperative PNI (p = 0.007) and pTNM stage (p < 0.001) were significantly associated with disease-free survival in rectal MAC patients. Nomograms for overall survival and disease-free survival were developed (C-index: 0.739 and 0.764). Conclusion: Preoperative AGR and PNI can act as effective predictors for survival for rectal MAC patients.

Mucinous rectal cancer: concepts and imaging challenges

Rectal adenocarcinoma with mucinous components is an uncommon type of rectal cancer with two distinct histologic subtypes: mucinous adenocarcinoma and signet-ring cell carcinoma. Mucin can also be identified as pattern of response after neoadjuvant treatment. On imaging modalities, mucin typically demonstrates high signal intensity on T2-weighted images, low attenuation on computed tomography, and may be negative on 18-fluorodeoxyglucose positron emission tomography. After neoadjuvant CRT, cellular and acellular mucin share similar imaging features, and differentiating them is currently the main challenge faced by radiologists. Radiologists should be aware of pros, cons, and limitations of each imaging modality in the primary staging and restaging to avoid misinterpretation of the radiological findings.

Current controversy, confusion, and imprecision in the use and interpretation of rectal MRI

There has been a rapid increase in the utilization of MRI in rectal cancer staging in the USA essentially replacing endorectal ultrasound and mimicking the trend in Europe seen in the 1990s and 2000s. Accompanying this trend, there is a demand, and recognized need, for greater precision and clarification of confusing, misunderstood and poorly understood concepts, facts, statements and nomenclature regarding rectal cancer and the use of pelvic MRI for diagnosis. As such, this Review, part evidence-based and part expert opinion, will attempt to elucidate and clarify several concepts the authors have encountered in 25 years of imaging rectal cancer, focusing on MRI.

Mucinous rectal cancer: concepts and imaging challenges

Rectal adenocarcinoma with mucinous components is an uncommon type of rectal cancer with two distinct histologic subtypes: mucinous adenocarcinoma and signet-ring cell carcinoma. Mucin can also be identified as pattern of response after neoadjuvant treatment. On imaging modalities, mucin typically demonstrates high signal intensity on T2-weighted images, low attenuation on computed tomography, and may be negative on 18-fluorodeoxyglucose positron emission tomography. After neoadjuvant CRT, cellular and acellular mucin share similar imaging features, and differentiating them is currently the main challenge faced by radiologists. Radiologists should be aware of pros, cons, and limitations of each imaging modality in the primary staging and restaging to avoid misinterpretation of the radiological findings.

Type of preoperative therapy and stage-specific survival after surgery for rectal cancer: a nationwide population-based cohort study

Preoperative chemoradiation therapy (CRT) may induce downstaging in rectal cancer (RC). Short-course radiation therapy (SC-RT) with immediate surgery does not cause substantial downstaging. However, the TNM classification adds the “y” prefix in both groups to indicate possible treatment effects. We aim to compare stage-specific survival in these patients. RC patients treated with surgery only, preoperative SC-RT followed by surgery within 10 days, or preoperative CRT, and diagnosed between 2008 and 2014 were included in this population-based study. Clinicopathological and outcome characteristics were analyzed. The study included 11,925 patients. Large discrepancies existed between clinical and pathological stages after surgery only. Surgery-only patients were older with more comorbidities compared with SC-RT and CRT and had worse 5-year survival (64%, 76%, and 74%, respectively; p < 0.001). Five-year survival for stage I was similar after CRT and SC-RT (85% vs. 85%; p = 0.167) and comparable between CRT-treated patients with stage I and those reaching a pathological complete response (pCR; 85% vs. 89%; p = 0.113). CRT was independently associated with worse overall survival compared with SC-RT for stage II (HR 1.57 [95%CI 1.27–1.95]; p < 0.001) and stage III (HR 1.43 [95%CI 1.23–1.70]; p < 0.001). Stage I disease after CRT has an excellent prognosis, comparable with pCR and with same-stage SC-RT-treated patients without regression. Stage II or III after CRT has worse prognosis than after SC-RT with immediate surgery. TNM should take the impact of preoperative therapy type on stage-specific survival into account. In addition, clinical stage was a poor predictor of pathological stage.

Mucinous colorectal adenocarcinoma: clinical pathology and treatment options

Mucinous colorectal adenocarcinoma is a distinct subtype of colorectal cancer (CRC) characterized by the presence of abundant extracellular mucin which accounts for at least 50% of the tumor volume. Mucinous colorectal adenocarcinoma is found in 10%–20% of CRC patients and occurs more commonly in female and younger patients. Moreover, mucinous colorectal adenocarcinoma is more frequently located in the proximal colon and diagnosed at an advanced stage. Based on its molecular context, mucinous colorectal adenocarcinoma is associated with the overexpression of mucin 2 (MUC2) and mucin 5AC (MUC5AC) proteins. At the same time, it shows higher mutation rates in the fundamental genes of the RAS/MAPK and PI3K/Akt/mTOR pathways. Mucinous colorectal adenocarcinoma also shows higher rates of microsatellite instability (MSI) than non-mucinous colorectal adenocarcinoma which might correlate it with Lynch syndrome and the CpG island methylator phenotype. The prognosis of mucinous colorectal adenocarcinoma as to non-mucinous colorectal adenocarcinoma is debatable. Further, the impaired responses of mucinous colorectal adenocarcinoma to palliative or adjuvant chemotherapy warrant more studies to be performed for a specialized treatment for these patients. In this review, we discuss the molecular background and histopathology of mucinous colorectal adenocarcinoma, and provide an update on its prognosis and therapeutics from recent literatures.

HER2 as a limited predictor of the therapeutic response to neoadjuvant therapy in locally advanced rectal cancer

Human epidermal growth factor 2 (HER2) is a candidate therapeutic and prognostic marker for rectal cancer treated with neoadjuvant chemoradiotherapy. The specific frequency and prognostic role of HER2 protein expression and HER2 gene amplification in those rectal cancers has not been fully investigated. Pretreatment biopsied and surgically resected formalin-fixed paraffin-embedded tissues from 74 patients were retrospectively evaluated for HER2 protein expression and HER2 gene copy number using immunohistochemistry (IHC) and silver in situ hybridization (SISH), respectively. The tumor response to chemoradiation was evaluated with TNM staging and tumor regression grading (TRG) systems. Good response to chemoradiation therapy (TRG3), poor response (22 TRG1 and 19 TRG2), and TNM downstaging achieved in 33 (44.6%), 41 (55.4%), and 42 (56.8%) patients, respectively. The frequency of HER2 positivity is 17.6%, all of which were low-level HER2 gene amplification with 2.2 of median gene copy number ratio, detected in IHC0 (3/39), IHC1+ (2/18), IHC2+ (5/14) and IHC3+ (2/3). There was no association of HER2 positivity with clinicopathological parameters or survival. However, older age (≥61 years) and HER2 positivity were the independent predictive factors for non-down staging, while poorly differentiation and the papillary pattern were predictors for poor response. In multivariate analysis, good response proved as an only independent favorable prognostic factor affecting survivals. In conclusion, HER2 positivity may be predictive for a high-risk therapeutic resistance in rectal cancers. The discrepancy between IHC and gene amplification may result from the low-level amplification, which may explain lack of prognostic impact of HER2 positivity.

Impact of Mucin Proportion in the Pretreatment MRI on the Outcomes of Rectal Cancer Patients Undergoing Neoadjuvant Chemoradiotherapy

Purpose

The purpose of this study was to evaluate treatment response to neoadjuvant chemoradiotherapy (CRT) with regard to mucin status in pathology and pretreatment magnetic resonance imaging (MRI) in locally advanced rectal cancer.

Materials and Methods

Between 2003 and 2011, 306 patients with locally advanced rectal cancer received neoadjuvant CRT followed by surgery, and mucinous adenocarcinoma (MAC) was found in 27 (8.8%). All MAC patients had MRI before and after CRT and mucin proportion at MRI was measured. Therapeutic response was assessed by pathology after total mesorectal excision. To determine the optimal cut-off for mucin proportion in predicting good CRT response (near total or total regression) and negative circumferential resection margin (CRM), the receiver-operating characteristic analysis was performed.

Results

After neoadjuvant CRT, overall downstaging occurred in 44.4% of MAC and 72.4% of non-MAC (p=0.001), and positive CRM (≤1 mm) was observed more frequently in MAC (p<0.001). The optimal threshold for treatment response was 30% for mucin proportion, and there are nine with low mucin proportion (<30%) and 18 with high mucin proportion (≥30%) in pretreatment MRI. Negative CRM and tumor downstaging occurred more common in patients with mucin <30%, although statistically insignificant (p=0.071 and p=0.072, respectively). Regarding oncologic outcomes, lower mucin proportion in pretreatment MRI was associated with better disease-free and overall survival in MAC group (p=0.092 and 0.056, respectively), but the difference did not reach statistical significance.

Conclusion

Poor treatment outcome with neoadjuvant CRT was observed in patients with MAC, especially those with high mucin proportion at pretreatment MRI.

Use of magnetic resonance imaging in rectal cancer patients: Society of Abdominal Radiology (SAR) rectal cancer disease-focused panel (DFP) recommendations 2017

PURPOSE

To propose guidelines based on an expert-panel-derived unified approach to the technical performance, interpretation, and reporting of MRI for baseline and post-treatment staging of rectal carcinoma.

METHODS

A consensus-based questionnaire adopted with permission and modified from the European Society of Gastrointestinal and Abdominal Radiologists was sent to a 17-member expert panel from the Rectal Cancer Disease-Focused Panel of the Society of Abdominal Radiology containing 268 question parts. Consensus on an answer was defined as ≥ 70% agreement. Answers not reaching consensus (< 70%) were noted.

RESULTS

Consensus was reached for 87% of items from which recommendations regarding patient preparation, technical performance, pulse sequence acquisition, and criteria for MRI assessment at initial staging and restaging exams and for MRI reporting were constructed.

CONCLUSION

These expert consensus recommendations can be used as guidelines for primary and post-treatment staging of rectal cancer using MRI.

Tumor response after long interval comparing 5x5Gy radiation therapy with chemoradiation therapy in rectal cancer patients

BACKGROUND

In the era of organ preserving strategies in rectal cancer, insight into the efficacy of preoperative therapies is crucial. The goal of the current study was to evaluate and compare tumor response in rectal cancer patients according to their type of preoperative therapy.

METHODS

All rectal cancer patients diagnosed between 2005 and 2014, receiving radiation therapy (RT, 5 × 5Gy; N = 764) or chemoradiation therapy (CRT; N = 5070) followed by total mesorectal excision after an interval of 5-15 weeks were retrieved from the nationwide Netherlands Cancer registry. Logistic regression was used for multivariable analysis.

RESULTS

Median age of patients treated with RT was 76 years (range 28-92) compared to 64 years (range 21-92) for patients treated with CRT (P < 0.001). Patients treated with RT had a significantly lower clinical stage (P < 0.001). A complete pathologic response (ypT0N0) was found in 9.3% of patients treated with RT, significantly less than in patients treated with CRT (17.5%; odds ratio [OR] 0.37, 95% confidence interval [CI] 0.24-0.57). A good response (ypT0-1N0) was observed in 17.5% of patients treated with RT and in 22.6% of patients treated with CRT (OR 0.70, 95% CI 0.51-0.95). Histological subtype, clinical stage and distance to anus were identified as independent predictors for tumor response.

CONCLUSIONS

Despite a more advanced clinical stage, complete pathologic response was more common in patients treated with CRT than in patients treated with RT. Prospective trials are needed to establish the differences in other outcome parameters, including the impact on organ preserving strategies.

Prognosis and value of preoperative radiotherapy in locally advanced rectal signet-ring cell carcinoma

As well known, signet-ring cell carcinoma (SRCC) is a rare histological subtype of colorectal adenocarcinoma, which has been associated with poor prognosis and resistant to non-surgery therapy compared with common adenocarcinoma. In this study, we assessed the effect of preoperative radiotherapy (PRT) for locally advanced rectal SRCC in a large patient group from the Surveillance, Epidemiology, and End Results program (SEER, 1988–2011) database. SRCC was found in 0.9% (n = 622) rectal cancer (RC) patients in our study. In the PRT setting, SRCC had significantly worse cancer-specific survival than mucinous adenocarcinoma and nonmucinous adenocarcinoma patients (log-rank, P < 0.001). In terms of SRCC, stage III RC patients benefited from PRT (log-rank, P < 0.001) while stage II did not (P = 0.095). The multivariate Cox proportional hazard model showed that PRT was an independent benefit factor in stage III rectal SRCC patients (HR, 0.611; 95% CI, 0.407–0.919; P = 0.018). In conclusion, SRCC was an independent predictor of poor prognosis in stage III RC patients, but not in stage II. In the PRT setting of locally advanced RC, SRCC patients had significantly worse prognosis. PRT was an independent prognostic factor associated with improved survival in stage III rectal SRCC.

Effect of Neoadjuvant Chemoradiotherapy on Locally Advanced Rectal Mucinous Adenocarcinoma: A Propensity Score-Matched Study

Aims. To compare the surgical and oncological outcomes of rectal mucinous adenocarcinomas treated with neoadjuvant chemoradiotherapy versus surgery alone. Methods. A total of 167 locally advanced rectal mucinous adenocarcinoma patients treated with neoadjuvant chemoradiotherapy and surgery alone between 2008 and 2014 were matched using propensity score; the surgical and oncological outcomes were compared. Results. Ninety-six patients were matched. Postoperative morbidity was similar between groups. Sphincter preservation rate was higher in patients receiving neoadjuvant chemoradiotherapy (79.2% versus 60.4%, P = 0.045), especially for tumors ≥ 3 cm but ≤5 cm from the anal verge (75.0% versus 44.0%, P = 0.036). With a median follow-up of 54.8 months, the 5-year overall survival rate (neoadjuvant chemoradiotherapy versus surgery alone: 79.6% versus 67.1%; P = 0.599) and disease-free survival rate (75.6% versus 64.2%; P = 0.888) were similar. The 5-year local recurrence rate was lower in patients receiving neoadjuvant chemoradiotherapy (7.7% versus 26.0%, P = 0.036), while no difference was observed in distant metastasis. A poor response to chemoradiation was associated with higher local recurrence (P = 0.037). Conclusions. Compared with surgery alone, neoadjuvant chemoradiotherapy was found to increase the sphincter preservation rate and reduce local recurrence, thus being beneficial for locally advanced rectal mucinous adenocarcinoma patients.

Adjuvant radiotherapy improves cause specific survival in stage II, not stage III mucinous carcinoma of the rectum

Background

The effect of adjuvant radiotherapy on the survival outcomes of patients with mucinous rectal cancer remains unclear. This study evaluated the 5-year cause specific survival (CSS) of patients with mucinous rectal cancer after surgery to determine whether adjuvant radiotherapy conferred a survival benefit.

Methods

An analysis of the Surveillance, Epidemiology, and End Results (SEER)-registered database was conducted of patients presenting with mucinous rectal cancer between 2004 and 2011. The primary endpoint was 5-year CSS; univariate and multivariate analyses were performed using Cox proportional hazards regression models.

Results

A total of 574 patients were included for analysis with 248 patients in postoperative radiotherapy group and 326 patients in surgery alone group. Preliminary analysis demonstrated that adjuvant radiotherapy was not associated with CSS (χ² = 0.560, P = 0.454). Subgroup analysis indicated that postoperative radiotherapy group had survival advantage in stage II rectal cancer (93.3% vs. 76.6%, χ² = 4.654, P = 0.031), but not in stage III rectal cancer (67.5% vs. 64.7%, χ² = 0.186, P = 0.666). Multivariate analysis demonstrated that postoperative radiotherapy group had a reduced risk of death on survival (HR 0.346; 95%CI 0.129-0.927, P = 0.035)

Conclusion

Postoperative radiotherapy is an independent factor for improvement in CSS in patients with stage II rectal mucinous adenocarcinoma, and it should be routinely recommended in these patients. But for stage III patients, considering the losing of CSS advantage and potential radiotherapy toxicity, postoperative radiotherapy should be recommended with great caution.

Mucinous Rectal Adenocarcinoma Is Associated with a Poor Response to Neoadjuvant Chemoradiotherapy: A Systematic Review and Meta-analysis

BACKGROUND

Mucinous adenocarcinoma represents a potentially poor prognostic subgroup of rectal cancer. A consensus on the effect of mucinous cancer on outcomes following neoadjuvant chemoradiotherapy and curative resection for rectal cancer has not been reached.

OBJECTIVE

The aim of the current study is to use meta-analytical techniques to assess the association between mucinous histology and response to neoadjuvant chemoradiotherapy in rectal cancer.

DATA SOURCES

A comprehensive literature search of PubMed, Embase, and The Cochrane Library was performed.

STUDY SELECTION

All studies examining the effect of mucinous histology on chemotherapeutic response in rectal cancer were included.

INTERVENTIONS

No direct interventions were performed.

MAIN OUTCOME MEASURES

Outcomes of mucinous rectal adenocarcinoma were compared with nonmucinous tumors by using random-effects methods to analyze data. Data are presented as ORs with 95% CIs. The main outcomes measured were the rates of pathological complete response, tumor and nodal downstaging, positive resection margin rate, local recurrence, and overall mortality.

RESULTS

Eight comparative series describing outcomes in 1724 patients were identified, 241 had mucinous tumors (14%). Mucinous tumors had a reduced rate of pathological complete response (OR, 0.078; 95% CI, 0.015-0.397; p = 0.002) and tumor downstaging (OR, 0.318; 95% CI, 0.185-0.547; p < 0.001) following neoadjuvant chemoradiotherapy with an increased rate of positive resection margin (OR, 5.018; 95% CI, 3.224-7.810; p < 0.001) and poorer overall survival (OR, 1.526; 95% CI, 1.060-2.198; p = 0.023) following resection. Mucin expression did not significantly affect nodal downstaging (OR, 0.706; 95% CI, 0.295-1.693; p = 0.435) or local recurrence (OR, 1.856; 95% CI, 0.933-3.693; p = 0.078). There was no across-study heterogeneity for any end point.

LIMITATIONS

Most studies were retrospectively designed, and there were variations in patient populations and duration of follow-up.

CONCLUSIONS

Mucinous rectal adenocarcinoma represents a biomarker for poor response to preoperative chemoradiotherapy and is an adverse prognostic indicator.

Treatment Interval between Neoadjuvant Chemoradiotherapy and Surgery in Rectal Cancer Patients: A Population-Based Study

Background

Neoadjuvant chemoradiation therapy (CRT) has been widely implemented in the treatment of rectal cancer patients, but optimal timing of surgery after neoadjuvant therapy is unclear. The purpose of this study was to evaluate the effects of prolonged intervals between long-course CRT and surgery in rectal cancer patients.

Methods

Data on all rectal cancer patients diagnosed between 2006 and 2011 were retrieved from the population-based Netherlands Cancer Registry; the main outcome parameters were pathologic complete response (pCR) and overall survival (OS). Outcomes were reported separately for patients with early tumors (ETs; N = 217) and locally advanced rectal cancer (LARC; N = 1073). Patients were divided into 2-week interval groups according to treatment interval, ranging from 5–6 to 13–14 weeks. Kaplan–Meier curves, and logistic regression and Cox regression models were used for data analysis.

Results

No significant difference in pCR rate was observed for ET patients according to treatment interval. Compared with a treatment interval of 7–8 weeks, pCR rates in LARC patients were higher after 9–10 weeks (18.4 %; odds ratio [OR] 1.56, 95 % CI 1.03–2.37) and 11–12 weeks of treatment interval (20.8 %; OR 1.94, 95 % CI 1.15–3.26). Treatment interval did not influence OS in ET or LARC patients.

Conclusions

Treatment intervals of 9–12 weeks between surgery and CRT seem to improve the chances of pCR in LARC patients, without an effect on OS. The length of treatment interval did not affect outcomes in patients with ET. The ongoing search for minimally invasive surgery drives the need for exploration of factors that improve pathologic response.

Electronic supplementary material

The online version of this article (doi:10.1245/s10434-016-5294-0) contains supplementary material, which is available to authorized users.

Significance of histologic tumor grade in rectal cancer treated with preoperative chemoradiotherapy followed by curative surgery: A multi-institutional retrospective study

BACKGROUND AND PURPOSE

To evaluate the pre-treatment clinical factors affecting recurrence and survival in rectal cancer patients who receive preoperative chemoradiotherapy (CRT) and curative surgery.

METHODS AND MATERIALS

The clinical data of 1782 patients from 8 institutions in Korea were analyzed. The potential prognostic factors that could be acquired before radical surgery were patient age, gender, clinical T and N stages, tumor size and location, tumor grade, carcinoembryonic antigen (CEA) level, and the concurrent chemotherapy regimen. The relapse-free survival (RFS), overall survival (OS), and cumulative incidence of locoregional and distant recurrence were analyzed according to the clinical factors.

RESULTS

Among the pre-treatment clinical factors, tumor grade, pre-CRT CEA level, tumor location, and clinical N stage were significant prognostic factors affecting the RFS. The high-grade tumor was the hazardous factor for RFS on the multivariate analysis [Hazard ratio (HR), 1.83; 95% confidence interval (CI), 1.29-2.58; p=0.001]. The 5-year RFS rate for high-grade tumors was significantly lower than that for low-grade tumors (63.8% vs. 78.8%, p<0.001). The tumor grade was a significant prognostic factor for distant recurrence (HR, 1.83, 95% CI, 1.29-2.58; p<0.001), but not for locoregional recurrence (HR, 1.49, 95% CI, 0.68-3.26; p=0.320) on the multivariate analysis. The 5-year OS rate for high-grade tumors was significantly lower than that for low-grade tumors (70.6% vs. 85.5%, p<0.001).

CONCLUSION

The tumor grade is the significant pre-treatment clinical factor for recurrence and survival in rectal cancer patients who receive preoperative CRT and curative surgery.

Prognostic Relevance of Mucinous Subtype in a Population-based Propensity Score Analysis of 40,083 Rectal Cancer Patients

BACKGROUND

The prognostic relevance of mucinous histology in colorectal cancer remains unclear, especially for rectal neoplasms. The objective of this study was to evaluate if mucinous subtype has a relevant impact on overall survival (OS) and cancer-specific survival (CSS) of patients with adenocarcinomas of the rectum.

METHODS

On the basis of the data set of the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute of the United States, patients with rectal cancer between 2004 and 2011 were identified. Risk-adjusted Cox regression analysis and propensity score methods were used to assess OS and CSS.

RESULTS

In total, 40,083 patients with stage I-IV rectal cancer, of whom 2483 (6.2 %) had mucinous histology, were included in this study. In unadjusted analysis, the 5-year OS and CSS for patients with a mucinous adenocarcinoma was 54.3 % [95 % confidence interval (CI) 52.0-56.7] and 61.4 % (95 % CI 59.1-63.9) compared to 66.4 % (95 % CI 65.8-67.0) and 74.5 % (95 % CI 73.9-75.1) for patients with nonmucinous adenocarcinoma (P < 0.001). The survival disadvantage persisting in risk-adjusted Cox proportional hazard regression analysis [hazard ratio (HR) 1.23, 95 % CI 1.15-1.31, P < 0.001 and 1.25, 95 % CI 1.16-1.35, P < 0.001) disappeared after propensity score matching (OS: HR = 0.96, 95 % CI 0.76-1.21, P = 0.722; CSS: HR 1.06, 95 % CI 0.80-1.40, P = 0.693).

CONCLUSIONS

This population-based, propensity score matched analysis shows that mucinous histology itself does not constrain survival in rectal cancer patients. Therefore, treatment decisions should not be different according to mucinous histology.

Prognostic Significance and Molecular Features of Colorectal Mucinous Adenocarcinomas: A Strobe-Compliant Study

Mucinous adenocarcinoma (MC) is a special histology subtype of colorectal adenocarcinoma. The survival of MC is controversial and the prognostic biomarkers of MC remain unclear. To analyze prognostic significance and molecular features of colorectal MC. This study included 755,682 and 1001 colorectal cancer (CRC) patients from Surveillance, Epidemiology, and End Results program (SEER, 1973-2011), and Linköping Cancer (LC, 1972-2009) databases. We investigated independently the clinicopathological characteristics, survival, and variety of molecular features from these 2 databases. MC was found in 9.3% and 9.8% patients in SEER and LC, respectively. MC was more frequently localized in the right colon compared with nonmucinous adenocarcinoma (NMC) in both SEER (57.7% vs 37.2%, P < 0.001) and LC (46.9% vs 27.7%, P < 0.001). Colorectal MC patients had significantly worse cancer-specific survival (CSS) than NMC patients (SEER, P < 0.001; LC, P = 0.026), prominently in stage III (SEER, P < 0.001; LC, P = 0.023). The multivariate survival analysis showed that MC was independently related to poor prognosis in rectal cancer patients (SEER, hazard ratios [HR], 1.076; 95% confidence intervals [CI], 1.057-1.096; P < 0.001). In LC, the integrated analysis of genetic and epigenetic features showed that that strong expression of PINCH (HR, 3.954; 95% CI, 1.493-10.47; P = 0.013) and weak expression of RAD50 (HR 0.348, 95% CI, 0.106-1.192; P = 0.026) were significantly associated with poor CSS of colorectal MC patients. In conclusion, the colorectal MC patients had significantly worse CSS than NMC patients, prominently in stage III. MC was an independent prognostic factor associated with worse survival in rectal cancer patients. The PINCH and RAD50 were prognostic biomarkers for colorectal MC patients.

Advances in the care of patients with mucinous colorectal cancer

The majority of colorectal cancers (CRCs) are classified as adenocarcinoma not otherwise specified (AC). Mucinous carcinoma (MC) is a distinct form of CRC and is found in 10-15% of patients with CRC. MC differs from AC in terms of both clinical and histopathological characteristics, and has long been associated with an inferior response to treatment compared with AC. The debate concerning the prognostic implications of MC in patients with CRC is ongoing and MC is still considered an unfavourable and unfamiliar subtype of the disease. Nevertheless, in the past few years epidemiological and clinical studies have shed new light on the treatment and management of patients with MC. Use of a multidisciplinary approach, including input from surgeons, pathologists, oncologists and radiologists, is beginning to lead to more-tailored approaches to patient management, on an individualized basis. In this Review, the authors provide insight into advances that have been made in the care of patients with MC. The prognostic implications for patients with colon or rectal MC are described separately; moreover, the predictive implications of MC regarding responses to commonly used therapies for CRC, such as chemotherapy, radiotherapy and chemoradiotherapy, and the potential for, and severity of, metastasis are also described.

The Increasing Relevance of Tumour Histology in Determining Oncological Outcomes in Colorectal Cancer

Colorectal cancer is not just one type of cancer. Differences in outcome and reaction to treatment can at least be partly explained by different histological and molecular subtypes. Recognition of these differences may influence treatment decisions. However, there is huge variation in the amount of information that is available. Several tumour types such as mucinous carcinoma, signet ring cell carcinoma, neuroendocrine carcinoma and adenosquamous carcinoma have such a distinct phenotype that they are readily recognised. However, due to the rarity of signet ring cell carcinoma and adenosquamous carcinoma, limited data are available. More recently defined subtypes, like medullary carcinoma, serrated adenocarcinoma and micropapillary carcinoma, are not adequately diagnosed, which limits research possibilities using large-scale data from registries. In the current review, we systematically describe the histologic subtypes with the clinical and molecular background. We evaluate their prognosis compared to adenocarcinoma not otherwise specified and speculate about the clinical relevance.