Large Cell Neuroendocrine Carcinoma of the Colon With Carcinomatosis Peritonei

Colorectal large-cell neuroendocrine carcinomas (NECs) are extremely rare and have very poor prognosis compared to adenocarcinomas. A 74-year-old man presented with abdominal pain, diarrhea and hematochezia. The histopathologic report of colonoscopic biopsy performed at a local clinic was a poorly differentiated carcinoma. An abdominopelvic computed scan revealed irregularly enhanced wall thickening at the sigmoid colon with regional fat stranding and lymphnode enlargement. He underwent a laparoscopic high anterior resection with selective peritonectomy for peritoneal carcinomatosis, intraoperative peritoneal irrigation chemotherapy, and early postoperative intraperitoneal chemotherapy for 5 days. The tumor had a high proliferation rate (mitotic count > 50/10 HPFs and 90% of the Ki-67 index) and lymph-node metastases had occurred. On immunohistochemistry, the tumor cells expressed CD56 and synaptophysin. Large-cell NEC was confirmed. Systemic chemotherapy with cisplatin/etoposide was done. The patient is still alive after 3 years with no evidence of recurrence.

Correlation Between Bowel Preparation and the Adenoma Detection Rate in Screening Colonoscopy

PURPOSE: The adenoma detection rate is commonly used as a measure of the quality of colonoscopy. This study assessed both the association between the adenoma detection rate and the quality of bowel preparation and the risk factors associated with the adenoma detection rate in screening colonoscopy. METHODS: This retrospective analysis involved 1,079 individuals who underwent screening colonoscopy at the National Cancer Center between December 2012 and April 2014. Bowel preparation was classified by using the Aronchick scale. Individuals with inadequate bowel preparations (n = 47, 4.4%) were excluded because additional bowel preparation was needed. The results of 1,032 colonoscopies were included in the analysis. RESULTS: The subjects' mean age was 53.1 years, and 657 subjects (63.7%) were men. The mean cecal intubation time was 6.7 minutes, and the mean withdrawal time was 8.7 minutes. The adenoma and polyp detection rates were 28.1% and 41.8%, respectively. The polyp, adenoma, and advanced adenoma detection rates did not correlate with the quality of bowel preparation. The multivariate analysis showed age ≥ 60 years (hazard ratio [HR], 1.42; 95% confidence interval [CI], 1.02–1.97; P = 0.040), body mass index ≥ 25 kg/m² (HR, 1.56; 95% CI, 1.17–2.08; P = 0.002) and current smoking (HR, 1.44; 95% CI, 1.01–2.06; P = 0.014) to be independent risk factors for adenoma detection. CONCLUSION: The adenoma detection rate was unrelated to the quality of bowel preparation for screening colonoscopy. Older age, obesity, and smoking were independent risk factors for adenoma detection.

Diagnostic and prognostic value of preoperative ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography for colorectal cancer: comparison with conventional computed tomography

BACKGROUND/AIMS: ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) has been used for preoperative staging of colorectal cancer (CRC). However, the diagnostic accuracy of FDG-PET/CT for detection of lymph node or distant metastasis and its prognostic role have not been well established. We therefore evaluated the diagnostic and prognostic value of FDG-PET/CT in comparison with conventional CT for CRC. METHODS: We investigated 220 patients who underwent preoperative FDG-PET/CT and CT, followed by curative surgery for CRC. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of FDG-PET/CT and CT for detection of lymph node metastasis and distant metastasis were evaluated. In addition, we assessed the findings of FDG-PET/CT and CT according to outcomes, including cancer recurrence and cancer-related death, for evaluation of prognostic value. RESULTS: For detection of lymph node metastasis, FDG-PET/CT had a sensitivity of 44%, a specificity of 84%, and an accuracy of 67%, compared with 59%, 65%, and 62%, respectively, for CT (P=0.029, P=0.000, and P=0.022). For distant metastasis, FDG-PET/CT had a sensitivity of 79%, a specificity of 94%, and an accuracy of 93%, compared with 79%, 87%, and 86%, respectively, for CT (P=1.000, P=0.004, and P=0.037). In addition, positive findings of lymph node metastasis and distant metastasis on FDG-PET/CT were associated significantly with cancer recurrence or cancer-related death (P=0.009, P=0.001, respectively). CONCLUSIONS: Preoperative FDG-PET/CT had a higher specificity and accuracy compared to CT for detection of lymph node metastasis and distant metastasis of CRC. In addition, FDG-PET/CT could be a valuable prognostic tool for CRC.

Quality of life changes during adjuvant chemotherapy in patients with colon cancer

PURPOSE: The survival of advanced colon cancer patients has increased due to the development of surgical techniques and adjuvant chemotherapy. The administration of adjuvant chemotherapy after curative resection is generally accepted as a standard of care. The primary endpoint of chemotherapy should include not only tumor response and survival, but also impact on the quality of life (QoL). We evaluated changes in QoL during adjuvant chemotherapy in patients with colon cancer.METHODS: Between October 2009 and February 2012, 56 patients with stage II and III colon cancer received the combination adjuvant chemotherapy 5-flurouracil/folinic acid with oxaliplatin (FOLFOX). Patients were asked to complete the QoL questionnaire QLQ-C30 version 3 before and after 6 cycles of adjuvant chemotherapy.RESULTS: There was no significant difference in the QoL between the start of chemotherapy and after the completion of 6 cycles. After completion of 6 cycles, global QoL was worse in patients >70 years of age. The functional scale score was low in patients with chemotherapy schedules delayed more than 2 times due to adverse events. Patients with body weight increases greater than 5% scored lower on symptom scales. Interestingly, patients with peripheral neuropathy scored higher on symptom scales.CONCLUSION: QoL changes during adjuvant chemotherapy did not show significant differences. After the sixth chemotherapy, QoL was affected by age, body weight gain, delay of the scheduled chemotherapy, and peripheral neuropathy. Therefore, the proper attitude of physicians focused on reassurance and education of patients is very important during chemotherapy.

Impact of Hyperglycemia on Survival and Infection-Related Adverse Events in Patients with Metastatic Colorectal Cancer Who Were Receiving Palliative Chemotherapy / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Non-metastatic colorectal cancer patients with diabetes have poor overall survival than those without diabetes. However, the effect of hyperglycemia on survival after diagnosis of metastatic colorectal cancer (CRC) has not been assessed. Therefore, we assessed the impact of hyperglycemia on the survival and infection-related adverse events (AEs) in patients with metastatic CRC. MATERIALS AND METHODS: We reviewed the records of 206 patients with newly diagnosed metastatic CRC who were treated with palliative chemotherapy from March 2000 to December 2012 at Chungbuk National University Hospital. The mean glucose level of each patient was calculated using all available glucose results. RESULTS: The mean glucose levels ranged between 76.8 and 303.5 mg/dL, and patients were categorized into quartiles in accordance to their mean glucose level: group 1 ( 142.6 mg/dL). The median overall survival for patients in groups 1, 2, 3, and 4 were 22.6, 20.1, 18.9, and 17.9 months, respectively; however, this difference was not statistically significant (p=0.643). Compared with patients in group 1, those in groups 2, 3, and 4 were at a higher risk of infection-related AEs, according to a multivariate analysis (p=0.002). CONCLUSION: Hyperglycemia was not associated with shorter survival; however, it was associated with infection-related AEs in patients with newly diagnosed metastatic CRC receiving palliative chemotherapy.

Mesh-Based Transperineal Repair of a Perineal Hernia After a Laparoscopic Abdominoperineal Resection

A perineal hernia (PH) is formed by a protrusion of intra-abdominal viscera through a defect in the pelvic floor. This is a rare complication after a conventional abdominoperineal resection (APR). However, the risk of a PH may be increased after a laparoscopic resection because this technique can cause fewer postoperative adhesions, predisposing the small bowel to sliding down toward the pelvis. However, only a few case reports describe the transperineal approach for the repair of a PH after a laparoscopic APR. We present a case of a PH after a laparoscopic APR; the PH was repaired with synthetic mesh by using a transperineal approach. A transperineal approach using a mesh to reconstruct the pelvic floor is less invasive and more effective. We suggest that this technique should probably be the first choice for treating an uncomplicated PH that occurs after a laparoscopic APR.

Multicenter nonrandomized trial of ramosetron versus palonosetron in controlling chemotherapy-induced nausea and vomiting for colorectal cancer

PURPOSE: Chemotherapy-induced nausea and vomiting (CINV) have a negative impact on patients' quality of life and frequently pointed to as a major factor for treatment abandonment. Serotonin (5-HT3) receptor antagonist is considered as key treatment for CINV. Ramosetron and palonosetron are recently developed 5-HT3 receptor antagonists and known as more superior than other first-generation 5-HT3 receptor antagonists. The purpose of this study was to compare the efficacy of ramosetron and palonosetron and determine which drug is more effective for prevention of CINV. METHODS: Colorectal cancer patients treated with chemotherapy were enrolled consecutively. Patients were assigned to receive intravenous injection of ramosetron 0.3 mg or palonosetron 0.25 mg at 30 minutes before initiation of moderately emetogenic chemotherapy. Ramosetron group added oral administration of 0.1 mg ramosetron on the second and third days of chemotherapy. Efficacy parameter consisted of nausea and vomiting. RESULTS: Ninety-one patients received ramosetron and 89 patients received palonosetron. Presentation of vomiting and nausea symptoms was not significantly different between the two groups during acute (0-24 hours) and delayed period (after 24 hours). CONCLUSION: The incidence of CINV between the ramosetron and the palonosetron group has not shown any difference during acute, delayed, and overall period.

ERRATUM: Correction for affiliation of the 8th author-corresponding author. Multicenter nonrandomized trial of ramosetron versus palonosetron in controlling chemotherapy-induced nausea and vomiting for colorectal cancer

The affiliation of the 8th author was misprinted.

Prospective multicenter phase II clinical trial of FOLFIRI chemotherapy as a neoadjuvant treatment for colorectal cancer with multiple liver metastases / 대한외과학회지

PURPOSE: This study evaluated the efficacy of neoadjuvant chemotherapy combining 5-flurouracil/folinic acid with irinotecan (FOLFIRI) in colorectal multiple liver metastases regardless of resectability. METHODS: Forty-four patients with multiple (at least two) colorectal liver metastases were enrolled at seven tertiary referral hospitals between May 2007 and September 2010. All patients received the FOLFIRI chemotherapeutic regimen. Response to chemotherapy was assessed after three cycles (6 weeks) and once more after six cycles (12 weeks) of treatment. RESULTS: Objective response was noted in 27 patients (61.4%) and 4 patients (9.1%) had progressive disease. Of 44 patients, 10 patients (22.7%) underwent curative surgery (R0 resection) and 34 patients did not receive R0 resection. Grades 3 to 4 hematological toxicity was noted in 12 patients (27.3%) and grades 3 to 4 nonhematologic toxicity was identified in 5 patients (11.4%). CONCLUSION: FOLFIRI chemotherapy as a neoadjuvant chemotherapy for multiple colorectal liver metastases regardless of resectability demonstrated the possibility of R0 resection, high rate of objective response, and tolerable toxicities in this study.

Podoplanin, alpha-Smooth Muscle Actin or S100A4 Expressing Cancer-Associated Fibroblasts Are Associated with Different Prognosis in Colorectal Cancers

The interactions between the tumor microenvironment and tumor cells determine the behavior of the primary tumors. Whether cancer-associated fibroblasts (CAF) have a tumor progressive or a protective role likely depends on the type of tumor cells and the CAF subpopulation. In the present study, we analyzed the prognostic significance of CAF subpopulations in colorectal cancer (CRC). CAF phenotypes were analyzed in 302 CRC patients by using antibodies against podoplanin (PDPN), alpha-smooth muscle actin (alpha-SMA), and S100A4. The relationship between the CAF phenotypes and 11 clinicopathological parameters were evaluated and their prognostic significance was analyzed from the disease-free and overall survival times. We observed that at the tumor invasive front, PDPN CAFs were present in 40% of the cases, and S100A4 or alpha-SMA CAFs were detected in all the cases. PDPN/S100A4 and alpha-SMA/S100A4 dual-stained CAFs were observed in 10% and 40% of the cases, respectively. The PDPN+ CAFs were associated with 6 favorable clinicopathological parameters and prolonged disease-free survival time. The PDPN-/alpha-SMA(high) CAFs were associated with 6 aggressive clinicopathological parameters and tended to exhibit shorter disease-free survival time. On the other hand, the PDPN-/S100A4(high) CAFs were associated with 2 tumor progression parameters, but not with disease prognosis. The PDPN+ CAF phenotype is distinct from the alpha-SMA or S100A4 CAFs in that it is associated with less aggressive tumors and a favorable prognosis, whereas the PDPN-/alpha-SMA(high) or PDPN-/S100A4(high) CAFs are associated with tumor progression in CRC. These findings suggest that CAFs can be a useful prognostic biomarker or potential targets of anti-cancer therapy in CRC.

Unusual Case of Solitary Perineal Subcutaneous Metastasis From Sigmoid Colon Cancer

Subcutaneous metastasis from colorectal cancer is an unusual presentation. Most perineal subcutaneous metastases are found in extensive involvements of multiorgan metastases or local recurrences of rectal cancer. Subcutaneous metastasis from colon cancer is considered as a distant metastasis with poor prognosis. We report an unusual case of solitary subcutaneous metastasis beneath the perineum without solid organ involvement after a curative anterior resection for sigmoid colon cancer. The patient underwent a perineal resection, and chemotherapy with the FOLFOX (fluorouracil, leucovorin, and oxaliplatin) regimen was instituted. Eight months later, multiple lung metastases were found, and chemotherapy was restarted with the FOLFIRI (fluorouracil, leucovorin, and irinotecan) regimen. However, lung metastases progressed, and new metastases appeared at the adrenal glands, the kidneys and the cerebellum. The patient died 30 months after the diagnosis of perineal subcutaneous metastasis. He lived relatively long in comparison with patients in previous reports.

Treatment of a Recurrent Rectourethral Fistula by Using Transanal Rectal Flap Advancement and Fibrin Glue: A Case Report

Rectourethral fistulas (RUFs) in adults are rare and could result from complicated trauma, and prostatic or rectal surgery. RUFs have been treated initially by using primary repair and omental interposition with or without a colostomy during surgery. Recurrent RUFs require complex surgery, such as a low rectal resection and coloanal anastomosis, an interposition flap of the datos muscle or gracilis muscle, and others. Recently, transanal rectal flap advancement and fibrin glue injection have provided an effective occlusion of RUFs. However, no reports about this technique exist for cases of recurrent RUFs. We report a case of a recurrent RUF successfully repaired by using transanal rectal flap advancement combined with fibrin glue injection into the fistula tract. The postoperative course was uneventful without complications. At the 1-year follow-up, no complications such as urethral stricture or recurrence existed, and voiding was normal without anal incontinence.

Clinical predictive factors of pathologic tumor response after preoperative chemoradiotherapy in rectal cancer

PURPOSE: The aim of this study was to identify clinical predictive factors for tumor response after preoperative chemoradiotherapy (CRT) in rectal cancer. MATERIALS AND METHODS: The study involved 51 patients who underwent preoperative CRT followed by surgery between January 2005 and February 2012. Radiotherapy was delivered to the whole pelvis at a dose of 45 Gy in 25 fractions, followed by a boost of 5.4 Gy in 3 fractions to the primary tumor with 5 fractions per week. Three different chemotherapy regimens were used (5-fluorouracil and leucovorin, capecitabine, or tegafur/uracil). Tumor responses to preoperative CRT were assessed in terms of tumor downstaging and pathologic complete response (ypCR). Statistical analyses were performed to identify clinical factors associated with pathologic tumor response. RESULTS: Tumor downstaging was observed in 28 patients (54.9%), whereas ypCR was observed in 6 patients (11.8%). Multivariate analysis found that predictors of downstaging was pretreatment relative lymphocyte count (p = 0.023) and that none of clinical factors was significantly associated with ypCR. CONCLUSION: Pretreatment relative lymphocyte count (%) has a significant impact on the pathologic tumor response (tumor downstaging) after preoperative CRT for locally advanced rectal cancer. Enhancement of lymphocyte-mediated immune reactions may improve the effect of preoperative CRT for rectal cancer.

Prophylactic Central Compartment Node Dissection for Papillary Thyroid Carcinoma: Complication and Outcome / 대한내분비외과학회지

PURPOSE: Prophylactic central compartment node dissection is gaining acceptance in the treatment of papillary thyroid carcinoma (PTC). However, its benefits remain controversial. The aim of study was to evaluate the effects of prophylactic central compartment node dissection on the complication rate and the short-term disease-free survival rate. METHODS: Our treatment strategy for PTC without clinical evidence of lymph node metastasis has been changed from total thyroidectomy alone (group I) to total thyroidectomy with prophylactic central compartment node dissection (group II) since January 2007. Before and after 2007, 70 consecutive patients were selected in each group. RESULTS: The average age of patients was 46.3±11.8 years. Average follow-up period was 51.9±10.9 months. The average size of maximum diameters of the tumors was 1.3±0.8 cm. Lymph node metastasis was identified in 22.9% of patients in group II. Recurrent laryngeal nerve injury occurred in one patient in each group. Temporary and permanent hypoparathyroidism occurred in 32.9% and 2.9% in group I, 40.0% and 7.1% in group II respectively (P=0.483 and P=0.441, respectively). Locoregional recurrences developed in seven patients in group I. Fifty month disease-free survival rate was 90.0% and 100% in group I and group II, respectively (P=0.0078). CONCLUSION: Prophylactic central compartment node dissection did not seem to increase the risk of recurrent laryngeal nerve injury, but may increase the risk of temporary and permanent hypoparathyroidism. Prophylactic central compartment node dissection decreased the risk of locoregional recurrences, especially in central compartment. However, the size of metastatic lymph nodes in central compartment in the present study was relatively small and their clinical implication remains to be evaluated.

A Case of Colovesical Fistula Induced by Sigmoid Diverticulitis

Colonic diverticulosis has continuously increased, noticeably left-sided diseases, in Korea. A colovesical fistula is an uncommon complication of diverticulitis, and its most common cause is diverticular disease. Confirmation of its presence generally depends on clinical findings, such as pneumaturia and fecaluria. The primary aim of a diagnostic workup is not to observe the fistular tract itself but to find the etiology of the disease so that an appropriate therapy can be initiated. We present here the case of a 79-year-old man complaining of pneumaturia and fecaluria. On abdomen and pelvis CT, the patient was diagnosed as having a colovesical fistula due to sigmoid diverticulitis. After division of the adhesion between the sigmoid colon and the bladder, the defect of the bladder wall was repaired by simple closure. The colonic defect was treated with a segmental resection, including the rectosigmoid junction. The patient is doing well at 6 months after the operation and shows no evidence of recurrence of the fistula.

Successful Removal of a Migrated Catheter of Chemoport in Right Atrium

The use of totally implantable central venous access devices (chemoport) has increased with the development of chemotherapeutic agents in oncologic patients, especially with no venous access site. However, there can be various complications such as port site infection, thromboembolism, injury of central vein, fracture of catheter, and migration of catheter. We report a rare case of migration of catheter to right atrium due to the separation of the catheter from the chemoport.

Diagnosis of Acute Appendicitis Using Scoring System: Compared with the Alvarado Score

PURPOSE: This study evaluated the usefulness of a new scoring system in diagnosing acute appendicitis which expresses the patient's symptoms, physical examination, and laboratory findings more clearly and objectively. METHODS: A prospective study was conducted with 314 patients who were hospitalized with suspicion of acute appendicitis. After analyzing the symptoms, physical examination, and laboratory findings, 10 meaningful variables were selected, each of which were scored separately. The diagnostic value of the new scoring system was evaluated, and analyzed in comparison to the preexisting Alvarado score. RESULTS: Ten variables including vomiting, migration pain, fever, Dunphy's sign, Rovsing's sign, tenderness, rebound tenderness, increased white blood cell counts, increased neutrophil proportion, and increased CRP levels were associated with acute appendicitis. The new scoring system is developed by applying 1 point for each variable, with a total score of 10 points. In the new scoring system, a score above 5 points had sensitivity of 0.75, specificity of 0.73, positive predictive value of 0.92, and diagnostic accuracy of 0.71. The area under the receiver operating characteristic curve was 0.80, which is larger than 0.72 of the preexisting Alvarado score, and thus has a higher diagnostic accuracy. As acute appendicitis progresses, the average score tends to become significantly higher (P=0.001). CONCLUSION: The new scoring system, which objectively reflects the clinical variables of the patient's symptoms, physical examination and laboratory findings, will be useful in accurately diagnosing acute appendicitis and in quickly deciding a therapeutic policy in patients with right lower abdominal pain.

Voltage-dependent Ca2+ Current Identified in Freshly Isolated Interstitial Cells of Cajal (ICC) of Guinea-pig Stomach

The properties of voltage dependent Ca2+ current (VDCC) were investigated in interstitial cells of Cajal (ICC) distributed in the myenteric layer (ICC-MY) of guinea-pig antrum. In tissue, ICC-MY showed c-Kit positive reactions and produced driving potentials with the amplitude and frequency of about 62 mV and 2 times min(-1), respectively, in the presence of 1micrometer nifedipine. Single ICC-MY isolated by enzyme treatment also showed c-Kit immunohistochemical reactivity. These cells were also identified by generation of spontaneous inward current under K+-rich pipette solution. The voltage clamp experiments revealed the amplitude of - 329 pA inward current at irregular frequency. With Cs+-rich pipette solution at Vh=?80 mV, ICC-MY produced voltage-dependent inward currents (VDIC), and nifedipine (1micrometer) blocked VDIC. Therefore, we successfully isolated c-Kit positive single ICC from guinea-pig stomach, and found that ICC-MY potently produced dihydropiridine sensitive L-type voltage-dependent Ca2+ currents (VDCCL).

Management of the Symptoms after a Resection of the Rectum

Many patients have functional disturbances after a traditional restorative rectal resection, complaining of urgency, frequent bowel movements, and occasional fecal incontinence. The rectal reservoir function is disturbed, and this is related to the size of the rectal remnant and the elastic properties of the neorectal wall. A straight anastomosis is recommended when the reservoir capacity of the rectal remnant is sufficient. A side-to-end anastomosis is probably preferable to an end-to-end anastomosis. If a straight anastomosis is considered, the descending colon is much better than the sigmoid colon. If optimal functional results are to be obtained soon after surgery, construction of a pouch is recommended when the rectal remnant is very short. There seems to be a balance between continence without urgency and evacuation ability. For patients with weak sphincter muscles and habitually loose feces, the surgeon should tailor the length of the pouch to be longer whereas it should be made smaller for patients with a pre-operative tendency toward constipation. In the long-term, bowel adaptation may also enable the function after a straight anastomosis to approximate that of a colonic J-pouch anal anastomosis. Where the pelvis is too narrow for a bulky colonic J-pouch anal anastomosis, a coloplasty-anal- anastomosis is an option. The latter results in postoperative bowel function comparable with that of the colonic J-pouch. Traditionally, poor bowel function has been managed expectantly. The colonic adaptation may take one or two years to occur after a low anterior resection. The patient is advised to take adequate soluble fiber in the diet and to avoid foods which aggravate the bowel dysfunction. Those with increased stool frequency are prescribed constipating agents to help control the symptoms. Patients with rectal evacuation problems are prescribed regular laxatives and enemas.

Clinicopathologic Features of Sporadic Colorectal Cancer with MLH1/MSH2 Loss of Expression - Reduced Likelihood of Metastases

PURPOSE: This study was designed to determine the frequency of MMR defective sporadic colorectal cancer (CRC) by using immunohistochemistry and to investigate the correlation between the MMR status and the metastatic potential. METHODS: The study included 249 patients with sporadic colorectal cancer who underwent surgical resection. The MMR status was determined by using an immunohistochemical analysis of MLH1 and MSH2 expression. RESULTS: Twenty seven (10.8%) carcinomas showed abnormal MMR protein expression (18 MLH1 negative and 9 MSH2 negative) and were classified as MMR defective tumors whereas 222 tumors demonstrated normal MLH1/MSH2 immunoreactivity (MMR intact tumor). MMR defective tumors developed at significantly higher frequencies in a proximal site (59.3% vs. 27.5%, P=0.001) and tended to be larger in size (6.3+/-2.4 cm vs. 5.1+/-2.1 cm, P=0.026). They showed significantly lower overall stage, N stage, and M stage at the time of diagnosis (P=0.002, P=0.014, P=0.010, respectively). In patients who had MMR defective tumors, lymphocytic infiltration (40.7% vs. 8.7%, P<0.001) and poor differentiation (22.2% vs. 11.7%, P=0.012) were more frequently observed. Less frequently MMR defective tumors displayed lymphatic invasion (40.7% vs. 67.1%, P=0.007) and infiltrative borders (22.2% vs. 51.8%, P=0.004). The MMR defect was strongly associated with a decreased likelihood of lymph node (odds ratio: 0.34, 95% CI: 0.13~0.95) and distant organ metastases at diagnosis (odds ratio: 0.09, 95% CI: 0.01~0.94), independent of the clinicopathologic features. CONCLUSIONS: mmunohistochemical analysis revealed that 10.8% of sporadic CRC cases showed no staining for MLH1 or MSH2. Lymphatic invasion and distant metastases were found at lower rates in these MMR defective tumors.