Peritoneal lavage cytology in patients with curative resection for stage II and III colorectal cancer: A multi-institutional prospective study.

Aim: To clarify the usefulness of intraoperative lavage cytology in patients undergoing curative resection for pStage II-III colorectal cancer in a prospective multicenter study. Methods: Patients preoperatively diagnosed with stage II-III colorectal cancer between 2013 and 2017 from 20 hospitals were enrolled. Lavage cytology was performed twice during the surgery. The primary endpoint was the effect of lavage cytology on the 5-year relapse-free survival (RFS) in patients with pStage II-III colorectal cancer. The secondary endpoint was the effect of lavage cytology on the 5-year overall survival (OS) and peritoneal recurrence. Results: A total of 1378 patients were eligible for analysis. The number of patients with pStage II-III colorectal cancer was 670 and 708, respectively. Fifty-four patients (3.9%) had positive cytological results. In pStage II patients, the 5-year RFS rates with positive and negative cytology were 61.1% and 81.6%, respectively (p = 0.023). The 5-year OS rates were 67.1% and 91.7%, respectively (p = 0.0083). However, there was no difference in RFS or OS between pStage III patients with positive and negative cytology results. The peritoneal recurrence rates were 11.8% and 1.5% in pStage II patients with positive and negative cytology results, respectively (p = 0.032). These rates were 10.5% and 2.5% in patients with stage III disease, respectively (p = 0.022). Conclusion: Stage II colorectal cancer patients with negative cytology had better outcomes than those with positive cytology. Peritoneal lavage cytology is useful for predicting peritoneal recurrence after curative resection of stage II-III colorectal cancer.

Laparoscopic repair for internal hernia associated with colostomy: a case report.

A 63-year-old woman was admitted with abdominal pain two months after laparoscopic abdominoperineal resection for rectal cancer. Computed tomography revealed dilated small intestine had passed through a defect between the lifted sigmoid colon and abdominal wall. She was diagnosed with small bowel obstruction without strangulation due to internal hernia and managed nonoperatively based on her wish. Recurrence of intestinal obstruction occurred for which curative surgery was performed laparoscopically. The herniated intestine was restored to the normal position, and the hernia orifice was closed using barbed suture, on laparoscopic management. Internal hernia is a rare complication after colostomy that requires surgical management. Although laparoscopic approach on re-operation is difficult, laparoscopic surgery may be suitable for patients with IHAC in terms of required less use of adhesiolysis.

Genomic landscape and its prognostic significance in stage III colorectal cancer: JCOG1506A1, an ancillary of JCOG0910.

Large-scale genomic sequencing of colorectal cancers has been reported mainly for Western populations. Differences by stage and ethnicity in the genomic landscape and their prognostic impact remain poorly understood. We investigated 534 Japanese stage III colorectal cancer samples from the Phase III trial, JCOG0910. Targeted-capture sequencing of 171 potentially colorectal cancer-associated genes was performed, and somatic single-nucleotide variants and insertion-deletions were determined. Hypermutated tumors were defined as tumors with MSIsensor score >7 and ultra-mutated tumors with POLE mutations. Genes with alterations associated with relapse-free survival were analyzed using multivariable Cox regression models. In all patients (184 right-sided, 350 left-sided), mutation frequencies were TP53, 75.3%; APC, 75.1%; KRAS, 43.6%; PIK3CA, 19.7%; FBXW7, 18.5%; SOX9, 11.8%; COL6A3, 8.2%; NOTCH3, 4.5%; NRAS, 4.1%; and RNF43, 3.7%. Thirty-one tumors were hypermutated (5.8%; 14.1% right-sided, 1.4% left-sided). Modest associations were observed: poorer relapse-free survival was seen with mutant KRAS (hazard ratio 1.66; p = 0.011) and mutant RNF43 (2.17; p = 0.055), whereas better relapse-free survival was seen with mutant COL6A3 (0.35; p = 0.040) and mutant NOTCH3 (0.18; p = 0.093). Relapse-free survival tended to be better for hypermutated tumors (0.53; p = 0.229). In conclusion, the overall spectrum of mutations in our Japanese stage III colorectal cancer cohort was similar to that in Western populations, but the frequencies of mutation for TP53, SOX9, and FBXW7 were higher, and the proportion of hypermutated tumors was lower. Multiple gene mutations appeared to impact relapse-free survival, suggesting that tumor genomic profiling can support precision medicine for colorectal cancer.

Effect of Biologics on the Risk of Advanced-Stage Inflammatory Bowel Disease-Associated Intestinal Cancer: A Nationwide Study.

INTRODUCTION: The aim of this study was to evaluate the effect of biologics on the risk of advanced-stage inflammatory bowel disease (IBD)-associated intestinal cancer from a nationwide multicenter data set. METHODS: The medical records of patients with Crohn's disease (CD) and ulcerative colitis (UC) diagnosed with IBD-associated intestinal neoplasia (dysplasia or cancer) from 1983 to 2020 were included in this study. Therapeutic agents were classified into 3 types: biologics, 5-aminosalicylic acid, and immunomodulators. The pathological cancer stage was compared based on the drug used in both patients with CD and UC. RESULTS: In total, 1,042 patients (214 CD and 828 UC patients) were included. None of the drugs were significantly associated with cancer stage in the patients with CD. In the patients with UC, an advanced cancer stage was significantly associated with less use of biologics (early stage: 7.7% vs advanced stage: 2.0%, P < 0.001), 5-aminosalicylic acid, and immunomodulators. Biologic use was associated with a lower incidence of advanced-stage cancer in patients diagnosed by regular surveillance (biologics [-] 24.5% vs [+] 9.1%, P = 0.043), but this was not the case for the other drugs. Multivariate analysis showed that biologic use was significantly associated with a lower risk of advanced-stage disease (odds ratio = 0.111 [95% confidence interval, 0.034-0.356], P < 0.001). DISCUSSION: Biologic use was associated with a lower risk of advanced IBD-associated cancer in patients with UC but not with CD. The mechanism of cancer progression between UC and CD may be different and needs to be further investigated.

Optimal diagnostic criteria for lateral lymph node dissection using magnetic resonance imaging: a multicenter prospective study.

BACKGROUND: LLND in cases with suspected lateral lymph node (LLN) metastasis has been focused on as a novel treatment strategy in recent years. However, the optimal indication for LLND in rectal cancer patients has not been determined. This study aimed to establish the optimal indication for lateral lymph node dissection (LLND) in patients with rectal cancer using magnetic resonance imaging (MRI). METHODS: A total of 209 patients with rectal adenocarcinoma who underwent total mesorectal excision and LLND in 13 hospitals were prospectively registered. By matching the sizes of the harvested LNs and those in magnetic resonance imaging (MRI), the pathological outcome of each LN was confirmed one-by-one. Using parameters of the LLNs in MRI, the optimal diagnostic criteria for LLND were established. RESULTS: Of 3241 harvested LLNs, including 83 metastatic nodes, 1010 (31.1%) were visualized on MRI. Although all parameters assessed showed strong correlations with the presence of metastasis, none of these parameters could discriminate metastatic LLNs from non-metastatic nodes with sufficient sensitivity. However, by using the combination of long axis and short/long ratio in pretreatment MRI, we could establish optimal criteria for LLND. The sensitivity and specificity of the criteria for LLN metastasis were 94.3% and 40.2%, respectively. CONCLUSIONS: In conclusion, we established novel criteria for LLND in rectal cancer patients using MRI. Our criteria will be of great clinical use in determining indications for LLND.

Paraganglioma of the urinary bladder initially diagnosed as gastrointestinal stromal tumor requiring combined resection of the rectum: a case report.

BACKGROUND: Paraganglioma of the urinary bladder (Pub) is rare and presents with clinical symptoms caused by catecholamine production and release. The typical symptoms of Pub are hypertension, macroscopic hematuria, and a hypertensive crisis during micturition. The average size of detected Pubs is approximately 3 cm. Herein, we report a case of a large Pub in which the symptoms were masked by oral medication, precise preoperative diagnosis was difficult, and intraoperative confirmation of tumoral adhesion to the rectum resulted in hypertensive attacks during surgery. CASE PRESENTATION: A 64-year-old Japanese male with a history of hypertension and arrhythmia controlled with oral medication presented with a large tumor in the pelvic region, detected on examination for weight loss, with no clinical symptoms. Computed tomography and magnetic resonance imaging revealed a tumor measuring 77 mm in diameter in the posterior wall of the urinary bladder. The border with the rectum was unclear, and the tumor showed heterogeneous enhancement in the solid part with an enhancing hypodense lesion. Cystoscopy revealed compression of the bladder trigone by external masses; however, no tumor was visible in the lumen. Endoscopic ultrasonography-guided fine-needle aspiration revealed CD34-positive spindle-shaped cells in the fibrous tissue, suggestive of a mesenchymal neoplasm. The tumor was suspected to be a gastrointestinal stromal tumor, and surgery was performed. After laparotomy, we suspected that the tumor had invaded the rectum, and total cystectomy and anterior resection of the rectum were performed. Histologically, the tumor cells had granular or clear amphophilic cytoplasm with an oval nucleus and nests of cells delimited by connective tissue and vascular septations. Immunohistochemically, the tumor was positive for chromogranin A, CD56, and synaptophysin, and a diagnosis of paraganglioma of the urinary bladder was confirmed. There was no tumor recurrence at the 7-month follow-up. CONCLUSION: This case highlights the importance of careful examination of pelvic tumors, including endocrine testing, for detecting paraganglioma of the urinary bladder in patients with a history of hypertension or arrhythmia.

Clinical significance of CD8+ and FoxP3+ tumor-infiltrating lymphocytes and MFG-E8 expression in lower rectal cancer with preoperative chemoradiotherapy.

Preoperative chemoradiotherapy (CRT) for rectal cancer contributes to tumor down-staging and decreases locoregional recurrence. However, each patient shows a significantly different response to CRT. Therefore, the identification of predictive factors to CRT response would be beneficial to avoid unnecessary treatment. Cancer immunity in patients has been suggested to play an important role in the eradication of the tumor by CRT. In the present study, the utility of CD8+ and forkhead box P3 (FoxP3)+ tumor-infiltrating lymphocytes (TILs) and the expression of a novel immuno-regulatory factor, lactadherin (MFG-E8), in predicting CRT effectiveness in patients with rectal cancer was examined. A total of 61 patients with rectal cancer, who underwent curative resection following CRT were included in the study. The numbers of CD8+ and FoxP3+ TILs in a biopsy taken before CRT and MFG-E8 expression level in the specimens obtained at the time of the surgery after CRT were examined using immunohistochemical staining, and their association with clinicopathological characteristics, including patient survival, was determined. The tumors with more CD8+ TILs in the biopsy samples before CRT showed a significantly more favorable CRT response. The patients with tumors and a higher number of CD8+ TILs before CRT also exhibited significantly longer disease-free and overall survival times. Higher MFG-E8 expression level in post-CRT specimens was significantly associated with favorable CRT response; however, no significant association was found with any other clinicopathological characteristics, including survival time. The number of CD8+ TILs before CRT was a valuable predictor for CRT response and was associated with favorable prognosis in patients with lower rectal cancer and who were treated with CRT. High MFG-E8 expression level after CRT was also associated with a favorable CRT response.

Immunohistochemical Expression of CD133 and LGR5 in Ulcerative Colitis-associated Colorectal Cancer and Dysplasia.

BACKGROUND/AIM: Cluster of differentiation 133 (CD133) and leu cine-rich orphan G-protein-coupled receptor 5 (LGR5) are the most putative stem cell markers for colorectal cancer (CRC), and are associated with poor prognosis of patients with CRC. However, the role of CD133 and LGR5 in the inflammation-dysplasia-carcinoma sequence has not been fully elucidated. We examined the expression of CD133 and LGR5 in ulcerative colitis-associated CRC (UC-CRC; n=20) and UC-associated colorectal dysplasia (n=16) by immunohistochemistry. RESULTS: The rate of CD133-positive cases in UC-CRC was significantly higher than that in dysplasia (p=0.026), but that of LGR5 expression was not. Moreover, LGR5 expression was significantly positively associated with p53 expression (p=0.03), whereas CD133 expression positively correlated with p53 expression, but not significantly (p=0.10). CONCLUSION: CD133 may play an important role in tumor development in the context of the inflammation-dysplasia-carcinoma sequence. LGR5-positive cancer stem cells may play a critical role in the development of UC-CRC, particularly upon loss of p53 function.

G-CSF-producing Undifferentiated Pleomorphic Sarcoma Adjacent to the Ascending Colon and in the Right Iliopsoas Muscle: A Case Report and Review of the Literature.

Undifferentiated pleomorphic sarcoma (UPS) is a soft tissue sarcoma, occurring most commonly on the lower extremities. We herein report a rare case of primary UPS adjacent to the ascending colon and in the right iliopsoas muscle. Computed tomography of the abdomen revealed large masses, and the patient experienced a high-grade fever, leukocytosis, elevated serum C-reactive protein level, and hematopoietic activation on 18F-fluorodeoxyglucose-positron emission tomography. This inflammatory reaction was caused by granulocyte colony-stimulating factor secreted by tumor cells. Surgical resection was performed, and the inflammatory reaction disappeared immediately. The patient received adjuvant chemotherapy and survived one year after the operation without evidence of recurrence.

A case of unique endoscopic findings of intestinal endometriosis exposed to the mucosa: aggregation of papillary protruded bulges from the submucosal elevation of the rectum.

Intestinal endometriosis exposed to the mucosa is relatively rare. Therefore, its endoscopic findings with pit pattern and magnifying endoscopy with narrow-band imaging and clinicopathological features of intestinal endometriosis exposed to the mucosa have not been well documented until now. A 44-year-old woman was suspected to have gastrointestinal bleeding by positive fecal occult blood test. Colonoscopy revealed a hemicircular submucosal tumor whose surface was covered with easy-bleeding papillary bulges in the rectum. Pit pattern analysis and magnifying endoscopy with narrow-band imaging revealed straight microvessels among the straight pits arranged in a radial manner, and the avascular area with no pit pattern of the top of the bulge. These findings were different from those of polyps or cancer. Biopsy specimens from the protruded lesions were diagnosed as rectal mucosal endometriosis by hematoxylin-eosin staining and immunohistochemical examination. Surgical resection was suggested to the patient, but the patient did not favor surgical treatment. After the diagnosis dienogest treatment started and successfully relieved her abdominal pain. Malignant transformation of the endometriotic lesion has not arisen to this date.

Prognostic impact of doublecortin-like kinase 1 expression in locally advanced rectal cancer treated with preoperative chemoradiotherapy.

Preoperative chemoradiotherapy (CRT) is a standard therapy for locally advanced rectal cancer; however, the response varies depending on cases. Therefore, CRT-response predictors need to be elucidated. Cancer stem cells (CSCs), comprising a small part of tumors, are associated with tumor progression and recurrence due to their self-renewal and proliferation abilities. Doublecortin-like kinase 1 (DCLK1) is one of the several putative CSC markers; however, the clinical impact of its expression in rectal cancer has not been evaluated. The aim of this study was to clarify the clinical impact of DCLK1 expression in rectal cancer. We immunohistochemically evaluated DCLK1 expression in surgical specimens of 106 rectal cancer patients, including those who underwent preoperative CRT. The correlations between DCLK1 expression, and clinicopathological features and patient prognosis were then assessed. In rectal cancer patients treated with preoperative CRT, DCLK1 expression was significantly correlated with lymph node metastasis (p = 0.02) and poor cancer-specific survival (p = 0.049). However, in patients treated without preoperative therapy, no such correlation was found. DCLK1 expression can be associated with lymph node metastasis and poor cancer-specific survival in rectal cancer patients who receive CRT.

The short-term outcomes of robotic sphincter-preserving surgery for rectal cancer: comparison with open and laparoscopic surgery using a propensity score analysis.

PURPOSE: The aim of this study is to clarify the short-term outcomes of robotic sphincter-preserving surgery for rectal cancer in a retrospective study. METHODS: The short-term outcomes of robotic sphincter-preserving surgery (n = 130) were retrospectively compared to open (n = 234) and laparoscopic surgery (n = 318) by a propensity score analysis. RESULTS: Robotic surgery was performed more frequently for patients with lower rectal cancer (55%) than open (30%, p < 0.0001) or laparoscopic surgery (36%, p < 0.0001). None of the robotic surgery cases were converted to open surgery. After propensity score matching, robotic surgery was found to be associated with a longer operation time (342 vs. 230 min, p < 0.0001) and less blood loss (7 vs. 420 mL, p < 0.0001) than open surgery. The overall complication rate of robotic surgery was lower than that of open surgery (13 vs. 28%, p = 0.032). Robotic surgery was associated with a lower incidence of surgical site infections (SSIs) than laparoscopic surgery (0 vs. 7%, p = 0.028). There were no cases of anastomotic leakage after robotic surgery. The circumferential resection margin was involved in 0.8% of the patients who underwent robotic surgery; the incidence did not differ among the treatment groups. CONCLUSIONS: Although robotic surgery for rectal cancer was associated with a longer operation time, it was associated with a very low incidence of SSIs. The degree of safety was comparable to both open and laparoscopic surgery.

DCLK1 Expression in Colorectal Polyps Increases with the Severity of Dysplasia.

BACKGROUND: The expression of doublecortin-like kinase 1 (DCLK1) has been investigated in cancer; however not in precancerous adenomatous polyps. MATERIALS AND METHODS: Immunohistological expression of DCLK1 was evaluated in various grades of adenomas, cancerous polyps, and hyperplastic polyps in resected human tissue specimens. RESULTS: Ninety-two specimens were positive for DCLK1 and 134 were negative. Cancerous polyps showed a high DCLK1 positivity rate compared to adenomas (68.4% vs. 36.8%; p<0.01). The rate of DCLK1 positivity was not significantly different among the three grades of adenomas (mild, moderate, and severe). DCLK1 was highly positive in advanced adenomas than low risk adenomas (49.6% vs. 29.3%; p<0.01). CONCLUSION: The expression of DCLK1 was found in low-grade adenomas and increased with worsening severity of dysplasia. DCLK1 expression was highly observed in advanced adenomas, which had a clinically higher malignant potential.

[Three Long-Surviving Cases of Peritoneal Metastasis after Colorectal Cancer Resection].

We experienced 3 impressive colorectal cancer patients who developed peritoneal recurrences and underwent surgery several times and survived for more than 5 years. Case No. 1 was of a 44-year-old woman who underwent right hemicolectomy for her stage II A ascending colon cancer. She developed left ovarian metastasis, which was resected 3 years later. Five years later, she developed a pelvic peritoneal recurrence, which was resected successfully. Thirteen years later, she is doing well. Case No. 2 was of a 61-year-old man who underwent transverse colectomy for his stage II B colon cancer. He developed ileus 2 years 9 months later due to peritoneal recurrence, which was removed successfully. He underwent another resection for peritoneal metastasis 2 years 6 months later. He was administered 15 courses of FOLFOX6. He has remained cancer-free since 2009. Case No. 3 was of a 62-year-old man who underwent sigmoidectomy for his stage II A colon cancer. One year 8 months later, he underwent resection for a painful abdominal wall metastasis. Eight months later, he developed another abdominal wall recurrence, which was resected successfully. He underwent thoracoscopic resection 4 times for lung metastases and was given 16 courses of FOLFOX6. In 2009, he developed pelvic peritoneal nodules, which were resected. He later needed lymphadenectomy twice. He has remained cancer-free for the last 5 years and 6 months. Curative resection must be performed for a patient with peritoneal recurrence of colorectal cancer when surgery is indicated.

[Three Long-Surviving Cases of Recurrent Rectal Carcinomas Treated Non-Surgically and Cured].

Few cases of recurrent colorectal carcinomas were treated non-surgically and cured. Here, we report 3 such cases. Case No. 1 was of a 66-year-old woman, who underwent ISR for very low rectal cancer. Her disease Stage was tub2, T2N0M0. Two years and 6 months later, she developed intrapelvic recurrence involving sacral bones(S1-S3). Radiotherapy of 50 Gy followed by mFOLFOX6 with bevacizumab was administered for a year. She has been cancer-free for 6 years. Case No. 2 was of a 47-year-old man who underwent preoperative CRT of 40 Gy with 5-FU plus Leucovorin, and LAR was performed for very low rectal cancer. The disease Stage was tub2, T3N2M0. One year later, he was diagnosed with recurrent aortic lymph node metastasis. After 7 months of mFOLFOX6 with bevacizumab, he developed an anastomotic fistula. His chemotherapy was discontinued; he was cancer-free for 6 years. Case No. 3 was of a 56-year-old man who underwent TPE for low rectal cancer. The disease Stage was muc, T4b(urinary bladder)N0M1a(perianal skin). One year and 6 months later, he developed ileus and was diagnosed with intrapelvic recurrence. He underwent intestinal bypass operation, and CRT of 46 Gy with capecitabine was administered. He attained CR quickly, and was cancer-free for 5 years. Collecting similar cases to analyze the key to successful treatment is important.

Results of a 36-year surveillance program for ulcerative colitis-associated neoplasia in the Japanese population.

BACKGROUND AND AIM: Surveillance colonoscopy has been carried out for patients with long-standing ulcerative colitis who have an increased risk for colorectal cancer. The aim of the present study was to determine the incidence of and the risk factors for neoplasia. METHODS: We evaluated 289 ulcerative colitis patients who underwent surveillance colonoscopy between January1979 and December 2014. Cumulative incidence of neoplasia and its risk factors were investigated. Clinical stage and overall survival were compared between the surveillance and non-surveillance groups. RESULTS: Cumulative risk of dysplasia was 3.3%, 12.1%, 21.8%, and 29.1% at 10, 20, 30 and 40 years after the onset of ulcerative colitis, respectively. Cumulative risk of colorectal cancer was 0.7%, 3.2%, 5.2%, and 5.2% at 10, 20, 30 and 40 years from the onset of ulcerative colitis, respectively. Total colitis was a risk factor for neoplasia (P = 0.015; hazard ratio, 2.96). CONCLUSIONS: Our surveillance colonoscopy program revealed the incidence and risk factors of ulcerative colitis-associated neoplasias in the Japanese population. Total colitis is a risk factor for neoplasia.

Expression of the stem cell marker CD133 is related to tumor development in colorectal carcinogenesis.

BACKGROUND/OBJECTIVE: CD133 is currently considered the most robust surface marker for colorectal cancer stem cells. Two meta-analysis reports have suggested that CD133 expression is significantly associated with shorter survival, and CD133 may play an important role in the progression of colorectal cancer. However, the role of CD133 in colorectal adenoma has not been fully elucidated. METHODS: We used immunohistochemistry to evaluate CD133 expression in 200 endoscopically resected colorectal polyps from 200 patients and 20 normal mucosae between January 1993 and December 1996. RESULTS: CD133 staining was positive in 17.9% of the colorectal adenomas. Moreover, CD133 expression was associated with differentiation status (p = 0.003) and tumor size (p = 0.03). CONCLUSION: CD133 might play an important role in tumor development.

Leucine-rich repeat-containing G protein-coupled receptor 5 and CD133 expression is associated with tumor progression and resistance to preoperative chemoradiotherapy in low rectal cancer.

Preoperative chemoradiotherapy has been performed as a standard therapy for advanced low rectal cancer. Cancer stem cells (CSCs) have been reported to contribute to resistance to treatment and patient prognosis. Leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) and cluster of differentiation (CD133) are putative markers for CSCs. However, their prognostic ability remains unknown, and evaluation of a single marker can be insufficient due to the heterogeneity of cancer. LGR5 and CD133 expression was immunohistochemically evaluated in surgical specimens of 56 patients who received curative resection following chemoradiotherapy for advanced low rectal cancer. In addition, the correlations between their expression levels, and clinicopathological features and patient prognosis were asessed. LGR5 expression was significantly correlated with lymphatic invasion, lymph node metastasis, and tumor node metastasic (TNM) stage. CD133 expression was significantly correlated with vascular invasion and the tumor regression grade. Combined expression was significantly correlated with lymphatic invasion, tumor regression grade and TNM stage, but not with overall, and disease-free survival. LGR5 and CD133 expressions may represent useful markers associated with tumor progression and resistance to chemoradiotherapy in patients with low rectal cancer. Furthermore, combined expression of these markers may be a more useful marker compared with the expression of each single marker.

Predictive model for high-frequency microsatellite instability in colorectal cancer patients over 50 years of age.

Microsatellite instability (MSI) is an important biomarker for screening for Lynch syndrome, and also of response to immune checkpoint inhibitors. The aim of this study is to create a predictive model to determine which elderly patients with colorectal cancer (CRC) should undergo MSI and/or immunohistochemistry testing on the basis of clinicopathological data. We analyzed a test cohort of CRC patients aged ≥50 years (n = 2219) by multivariate logistic regression analyses to identify predictors of high-frequency MSI (MSI-H). The created prediction model was validated in an external cohort (n = 992). The frequency of MSI-H was 5.5% among CRC patients aged ≥ 50 years. The following five predictors of MSI-H were identified in the test cohort: female (1 point), mucinous component (2 points), tumor size ≥ 60 mm (2 points), location in proximal colon (3 points), and BRAF mutation (6 points). The area under curve (AUC) in the receiver-operating characteristic (ROC) analysis of this prediction model was 0.832 (95% confidence interval: 0.790-0.874). The sensitivity and specificity were 74.4% and 77.7%, respectively, for a cut-off score of 4 points. The receiver-operating characteristic curve of the validation cohort also showed an AUC of 0.856 (95% CI: 0.806-0.905). This prediction model is useful to select elderly CRC patients who should undergo MSI testing, and who may benefit from treatment with 5-FU-based adjuvant chemotherapy and cancer immunotherapy.

Clinical significance of mucinous components in rectal cancer after preoperative chemoradiotherapy.

PURPOSE: The clinical implications of mucinous components in rectal tumors, especially with regard to the efficacy of neoadjuvant chemoradiotherapy, remain unclear. METHODS: One hundred and thirty rectal cancer patients who received curative resection after neoadjuvant chemoradiotherapy were retrospectively reviewed. Patients were classified into 3 groups according to the proportion of extracellular mucin: low (<5 %), moderate (5-25 %), and high (>25 %). RESULTS: There were 82 (63.1 %), 26 (20.0 %), and 22 (16.9 %) patients in the low, moderate, and high mucin groups, respectively. Patients with a high mucinous tumor component were significantly more likely to have an advanced tumor stage (p = 0.010) and a shorter disease-free (p = 0.002) and distant recurrence-free survivals (p < 0.001), whereas the mucinous tumor component showed no correlation with local recurrence (p = 0.101). A high mucinous component was also an independent predictive factor for a shorter disease-free survival (p = 0.041, hazard ratio = 2.56) and distant recurrence-free survival (p = 0.001, hazard ratio = 5.74) according to a multivariate analysis. CONCLUSIONS: Because the mucinous components showed little correlation with local recurrence, mucinous cancer should not be a determining factor for chemoradiotherapy. However, the frequent occurrence of metachronous distant metastasis among patients with a high mucin component makes this a possible indicator for more robust postoperative adjuvant treatment and close surveillance of recurrence.