Usefulness of large-section cytokeratin 20 in the detection of intestinal wall infiltration and mesangial metastasis in patients with middle and lower rectal cancer

Objective: The objective of the study was to evaluate the usefulness of large-section cytokeratin 20 (CK20) staining technique in the detection of infiltration on the distal wall and mesangial metastasis in patients with middle and lower rectal cancer. Materials and Methods: A total of 62 patients with rectal cancer in the middle and lower segment were studied on large slices stained with CK20. Logistic regression was used to analyze the clinicopathologic factors related to distal low and middle rectal cancer metastasis to the mesorectum and rectal wall. Results: Two types of distal metastasis of the tumor were observed in the rectal wall in 18% (11/62) of the patients: submucosal invasion and muscularis propria invasion. The extent of distal metastasis to the rectal wall was around 0.5–1.0 cm. Four types of distal metastasis occurred in the mesorectum: lymph node invasion, blood and lymphatic vessel invasion, perineural invasion, and isolated neoplastic microfoci. Distal metastasis to the mesorectum was observed in 24% (15/62) of the patients. The extent of metastasis to the mesorectum was around 0.5–4.0 cm. Another three patients with microcapillary invasion in the distal mesorectum were observed by immunohistochemistry, as it was difficult to determine the spread by conventional hematoxylin and eosin staining. Conclusion: The large-section CK20 staining technique is useful for the detection of infiltration on the distal wall and mesangial metastasis in patients with middle and lower rectal cancer

Cytokeratin 20 negative Merkel cell carcinoma consistent with negative Merkel cell polyomavirus / 영남의대학술지

Merkel cell carcinoma (MCC) is a rare neuroendocrine tumor that is highly aggressive in nature and indolent in progression. The common risk factors for MCC are senility, prolonged exposure to sunlight, and immune deficient states. Moreover, Merkel cell polyomavirus has recently been characterized to be significantly associated with pathogenesis of MCC, including the expression of Cytokeratin 20 (CK20). Diagnosis is often difficult since histopathological results require a number of differential diagnoses through immunohistochemical (IHC) stains with other cutaneous malignancies. A 67-year-old man presented with a solitary domeshaped erythematous round mass on the left upper arm for 2 months. Biopsy and IHC studies revealed findings consistent with Merkel Cell Carcinoma of neuroendocrine origin. Common IHC stains usually confirm positive findings for CK20, which is also recognized as the key component in making the diagnosis. We present a CK20 negative MCC in light of expanding the knowledge of unusually stained IHC results in MCC.

The value of nuclear matrix protein 22, cytokeratin 20 and survivin mRNA as diagnostic markers for bladder tumor / 国际检验医学杂志

Objective To investigate the value of nuclear matrix protein 22(NMP22),cytokeratin 20(CK20) and survivin mRNA in the diagnosis of bladder cancer.Methods The research enrolled 107 cases with hematuresis or irritation sign of bladder,who were divided into the control group(44 cases) and the observed group(63 cases).Besides,45 health volunteers were chose as the health group.The urine level of NMP22 was detected by ELISA,and CK20 and survivin mRNA by RT-PCR to evaluate the value in the diagnosis of bladder tumor The sensitivities and specificities of NMP22,CK20 and survivin mRNA were compared and analyzed.Results The urine level of NMP22 in the observed group(37.92 U/mL) was obviously higher than that of health volunteers (4.31 U/mL) and the control group(7.04 U/mL).The difference was significant(P＜0.05).The sensitivity and specificity of NMP22 were 82.54％ and 61.36％ respectively,which was unrelated with the tumor stage.The sensitivities and specificities of CK20 and survivin mRNA were 83.70％,63.64％ and 85.71％,90.91％ respectively,which was positively related with the tumor stage.The sensitivities of CK20 and survivin mRNA in the T2-T4 subgroup were higher than that T1s-T1 subgroup.And there was statistic difference(P＜0.05).Conclusion There are significant evidences that the detections of NMP22,CK20 and survivin mRNA as non-invasive measures could be better methods and higher sensitivity and specificity in diagnosing bladder cancer.

The value of nuclear matrix protein 22, cytokeratin 20 and survivin mRNA as diagnostic markers for bladder tumor / 国际检验医学杂志

Objective To investigate the value of nuclear matrix protein 22(NMP22),cytokeratin 20(CK20) and survivin mRNA in the diagnosis of bladder cancer.Methods The research enrolled 107 cases with hematuresis or irritation sign of bladder,who were divided into the control group(44 cases) and the observed group(63 cases).Besides,45 health volunteers were chose as the health group.The urine level of NMP22 was detected by ELISA,and CK20 and survivin mRNA by RT-PCR to evaluate the value in the diagnosis of bladder tumor The sensitivities and specificities of NMP22,CK20 and survivin mRNA were compared and analyzed.Results The urine level of NMP22 in the observed group(37.92 U/mL) was obviously higher than that of health volunteers (4.31 U/mL) and the control group(7.04 U/mL).The difference was significant(P＜0.05).The sensitivity and specificity of NMP22 were 82.54％ and 61.36％ respectively,which was unrelated with the tumor stage.The sensitivities and specificities of CK20 and survivin mRNA were 83.70％,63.64％ and 85.71％,90.91％ respectively,which was positively related with the tumor stage.The sensitivities of CK20 and survivin mRNA in the T2-T4 subgroup were higher than that T1s-T1 subgroup.And there was statistic difference(P＜0.05).Conclusion There are significant evidences that the detections of NMP22,CK20 and survivin mRNA as non-invasive measures could be better methods and higher sensitivity and specificity in diagnosing bladder cancer.

Cytokeratin 20 negative Merkel cell carcinoma consistent with negative Merkel cell polyomavirus / 영남의대학술지

Merkel cell carcinoma (MCC) is a rare neuroendocrine tumor that is highly aggressive in nature and indolent in progression. The common risk factors for MCC are senility, prolonged exposure to sunlight, and immune deficient states. Moreover, Merkel cell polyomavirus has recently been characterized to be significantly associated with pathogenesis of MCC, including the expression of Cytokeratin 20 (CK20). Diagnosis is often difficult since histopathological results require a number of differential diagnoses through immunohistochemical (IHC) stains with other cutaneous malignancies. A 67-year-old man presented with a solitary domeshaped erythematous round mass on the left upper arm for 2 months. Biopsy and IHC studies revealed findings consistent with Merkel Cell Carcinoma of neuroendocrine origin. Common IHC stains usually confirm positive findings for CK20, which is also recognized as the key component in making the diagnosis. We present a CK20 negative MCC in light of expanding the knowledge of unusually stained IHC results in MCC.

Expression of Cyclin D1, Cytokeratin 7, Cytokeratin 20 and Vimentin in Papillary Thyroid Cancer and Relationship with Patient's Prognostic Factors / 대한내분비외과학회지

PURPOSE: Cyclin D1, cytokeratin(CK)7, CK20 and vimentin play an important role in tumorigenesis and tumor progression. Our aim was to investigate the expression of cyclin D1, CK7, CK20 and vimentin in 138 papillary thyroid cancer and relationship with clinicobiological factors. We also tried to evaluate the value of those as prognostic factors. METHODS: We performed an immunohistochemical assay for cyclin D1, CK7, CK20, and vimentin in 138 papillary thyroid cancer tissue specimens. The correlation between these factors and the clinicobiological parameters was analyzed. RESULTS: In 138 papillary thyroid carcinoma specimens, the expression of cyclin D1, CK7, CK20 and vimentin was seen in 118 cases (85.5%), 133 cases (96.4%), 2 cases (1.4%) and 119 cases (86.2%), respectively. In our cases, there was a significant association among the expressions of cyclin D1, gender and lymph node metastasis. However, no obvious correlation was found between those proteins, age, tumor size, tumor amount, lymph node status and the TNM stage. CONCLUSION: Our results suggested increased cyclin D1 expression was seen in female gender and it may be a useful marker for evaluating lymph node metastasis. However, the clinical utility of cyclin D1, CK7, CK20 and vimentin in thyroid cancer patients has to be further defined by prospective studies with larger sample sizes.

CK20 Positive Large-cell Neuroendocrine Carcinoma Presenting with Skin Metastases

We present a case of cytokeratin (CK) 20-positive large cell neuroendocrine carcinoma (LCNEC) presenting with multiple skin metastases as the primary manifestation. The patient was a 55-year-old man who presented with a one- month history of subcutaneous skin colored nodules of various sizes on his trunk. Pathologic examination of the skin revealed a nested and solid proliferation of large undifferentiated cells with vesicular nuclei and prominent nucleoli. Tumor cells were found to be immunohistochemically positive for CK 20, chromogranin A, synaptophysin, and CD56. Based on these features, the tumor was diagnosed as a large cell neuroendocrine carcinoma with multiple skin metastases. Computed tomographic (CT) imaging found metastatic foci in the liver, pleura, bone, and lymph nodes. We were unable to identify the primary site of origin. To the best of our knowledge, this is the first case of a large cell neuroendocrine carcinoma with a primary manifestation of multiple skin metastases.

Expression of VEGF-C and it's relationship with clinical pathologic characteristics in rectal cancer / 中华普通外科杂志

Objective To study the expression of VEGF-C and it's relationship with pathologic characteristics in rectal cancer.Method In this study 82 patients of mid to low rectal cancer underwent radieal resection from December 2007 to August 2008.Tumor tissues and lymph nodes were studied by immunohistochemical staining for VEGF-C expression in the tumor tissue and CK20 expression in D3 lymph nodes.Results were compared with the pathological results of mesenterium lymph nodes to explain the relationships between VEGF-C expressions and clinical pathologic characteristics.Data were analyzed with Chi square test.Result As for the expression of VEGF-C.significant differences were found between tumor stages(X~2=8.529,P<0.05)and between positive and negative lymph node metastasis(X~2=4.712,P<0.05).but there was no difference between that of mesenterium lymph node metastasis and D3 lymph node micrometastasis(X~2=0.017,P>0.05). Conclmion In rectal cancer,VEGF-C expression is correlated with tumor stage,type,metastasis and micrometastasis of lymph node.

Detecting mesorectal margin micrometastasis in total mesorectal excision patients with rectal carcinoma / 中华普通外科杂志

Objective To evaluate the impact of mesoreetal margin micrometastasis on local recurrence of rectal carcinoma after total mesorectal excision, and the relation between mesorectal margin mierometastasis and local recurrence. Methods Mesorectal margin specimens from 52 cases of rectal cancer after total mesorectal excision were studied by reverse transcriptase-polymerse chain reaction (RT-PCR) to detect the expression of CK20 mRNA. These patients were divided into CK20 mRNA positive and negative group and followed up for 3 years until local recurrence developed. Results In 52 patients with rectal cancer,21 cases were found to express CK20 mRNA in mesorectal margin, the expression rate of CK20 mRNA in Dukes A,B and C was 17% ,30% and 54% (P<0.05), respectively. The positive rate of well differentiated, moderately differentiated, poorly differentiated and undifferentiated carcinomas were 43%, 38% ,40% and 50% ,respectively(P>0.05 ). The incidence of local recurrence in CK20 mRNA positive and negative group was 24% and 3% , respectively. The difference was statistically significant between the two groups (P <0.05 ). Conclusion Detection of mesorectal margin CK20 mRNA as micrometastasis by RT-PCR in rectal carcinoma patients was a sensitive and effective way in predicting local recurrence. It is necessary for patients with positive mesorectal margin CK20 mRNA to undergo postoperative radiotherapy after total mesorectal excision.

Micrometastasis and dissection of lymph node of hepatodudenal ligament in gastric antral cancer / 上海第二医科大学学报

Objective To detect the micrometastasis status and necessity of dissection of lymph nodes of hepatodudenal ligament in advanced gastric antral cancer. Methods Eighty-six lymph node samples of hepatodudenal ligament which were negative in routine pathological examinations were collected from 45 gastric antral cancer patients with radical dissection.The expressions of CK20 mRNA were detected for the existence of micrometastasis by RT-PCR. Results Micrometastasis was found in 46 out of 86 lymph nodes(53.49%) and 23 out of 45 patients(51.11%),significantly different from the routine pathological examinations(both P

Sinonasal Low-Grade Adenocarcinoma: Report of Three Cases with the Clinicopathologic and Immunohistochemical Findings

Low-grade adenocarcinomas that primarily arise within the sinonasal tract are uncommon tumors. We report here on three cases of primary sinonasal low-grade adenocarcinomas. The patients were 2 females and 1 male with ages of 48, 57 and 64, respectively. Microscopically, the tumors had a well developed tubulopapillary growth pattern that consisted of columnar or pseudostratified cells with eosinophilic cytoplasm, round to oval nuclei and rare mitotic activity. On immunohistochemistry, the tumor cells were strongly positive for cytokeratin 7, but they were negative for cytokeratin 20, CDX-2 and p53. The Ki-67 labeling index was very low (mean: 1.9%). Two patients developed recurrent tumors at the primary site after the initial surgery, but all the patients are presently alive without metastasis 6 years 8 months, 8 years 8 months, and 11 months after the initial diagnosis. When considering the progress of these tumors, we think that it's important to understand the pathology of this entity to avoid underdiagnosis because a complete excision is required for effective treatment.

Detection of Micrometastasis in Draining Vein before & after Manipulation and Peritoneal Cavity in Colorectal Cancer by Reverse Transcriptase-Polymerase Chain Reactions for Cytokeratin 20 and Carcinoembryonic Antigen

PURPOSE: Micrometastasis is known as a significant predictor of prognosis in colorectal cancer patients. Recently, reverse transcriptase polymerase chain reaction (RT-PCR) has been applied to detecting micrometastasis. The drainage vein and peritoneum were examined and the micrometastases assessed in a series of colorectal cancer patients. METHODS: 22 patients, who were histologically diagnosed with colorectal cancer, and 8 patients of serosal and peritoneal brushing, were examined using RT-PCR to amplify the mRNAs for two epithelial markers, carcinoembryonic antigen (CEA) and cytokeratin 20 (CK-20). RESULTS: Among the 22 colorectal cancer patients, the positive rates of CK-20 and CEA mRNAs in the drainage vein were 10 (45%) and 7 (32%), and those of the serosal and peritoneal brushing were 6 (75%) and 5 (63%), respectively. CONCLUSION: These results suggest that the "no touch isolation technique" might be useful for operations in advanced colorectal cancer patients, and the brushing of the serosal or Douglas pouch can represent the micrometastasis status.

Proteomic Approach for Identifying Marker Proteins in the Urinary Bladder Precancerous Conditions Induced by BBN(N-butyl-N-(4-hydroxybutyl) nitrosamine) / 대한비뇨기과학회지

PURPOSE: Simple and noninvasive methods for the diagnosis of transitional cell carcinoma of the bladder are needed for the prevention of invasive tumor. A proteomic technology has recently been developed to facilitate protein profiling of biological mixtures. We investigated the role of this proteomic approach as a possible tool to detect the marker protein during the initiation stages on BBN-induced bladder carcinogenesis in rats. MATERIALS AND METHODS: Ten rats group A were given 0.05% BBN in drinking water for 12 weeks. Ten rats in group B were designated as a control group and were not given BBN. Whole urinary bladders of all rats were excised at 12 weeks from the beginning of the experiment. Conventional proteomics was performed with high resolution 2-D gel electrophoresis followed by computational image analysis and protein identification using mass spectrometry. RESULTS: A comparison of urinary bladder hyperplasia tissue with control tissue showed that five proteins; actin gamma2 propeptide, cytokeratin-20, proapolipoprotein, alpha2 actin(alpha-cardiac actin) and heat shock 27kDa protein 1 were over-expressed in hyperplastic tissues. Three protein; transcription factors, seminal vesicle secretory protein VI precursor and hypothetical protein RMT-7 were under-expressed in hyperplastic tissues. CONCLUSIONS: In an animal model system, BBN-induced, urinary bladder mucosal hyperplasia resulted in an increase in five proteins and a decrease in three proteins. Of these altered proteins, CK-20 and SVS-VI seem to be important. The proteomic approach may be a simple and noninvasive method for monitoring and follow-up of bladder cancer patients. However more information is needed regarding CK-20 expression in nonmalignant urological disease and in human tumor tissue, and regarding SVS-VI expression in other organs, for clinical usage.

E-cadherin and Cytokeratin Subtype Profiling in Effusion Cytology

Diagnostic utility of E-cadherin (E-CD) and cytokeratin (CK) subtype profiling in effusion cytology was investigated, employing immunocytochemistry on cellblock sections available from 211 metastatic carcinomas (MC), 6 mesotheliomas and 73 reactive mesothelial hyperplasias (MH). E-CD and monoclonal carcinoembryonic anti-gen (mCEA) stained 85% (120/141) and 65% (138/211) of MC, respectively. E-CD staining of MC was frequently heterogeneous (76/120) and absent in all anaplastic carcinomas (0/2). E-CD stained none (0/57) of MH while mCEA and epithelial membrane antigen (EMA) stained 12% (9/73) and 32% (16/32) of MH, respectively. Of 6 mesotheliomas, E-CD focally stained in 2 while mCEA stained none and EMA stained all. CK20 and CK17 stained none of MH or mesotheliomas. CK20 stained 15% of MC and CK 17 stained 22% of MC. CK5/6 and high molecular weight CK stained all mesotheliomas, 56% and 88% of MH, 26% and 39% of MC, respectively. MC showed predominant CK7+/20-expression, with the exceptions of MC from mucinous type of colon/rectum and ovary showing predominant CK20 positive. E-CD may be a useful positive marker for MC in effusion cytology, although it may focally stain in some mesotheliomas. Any positive staining for CK20 of MC suggests MC from the gastrointestinal tract or ovary among others.

Use of RT-PCR for CK20 and CEA mRNA to Detect of Micrometastasis in the Draining Venous Blood and the Peritoneum in Gastric Cancer Patients

PURPOSE: The benefits of the "no-touch" isolation technique that is usually performed to prevent the circulation of tumor cells are not evident. The aim of this study was to determine whether the no-touch isolation technique for treating gastrointestinal cancers could prevent the circulation of tumor cells detected by reverse transcriptase polymerase chain reaction (RT-PCR). Matrials and Methods: By using RT-PCR to amplify mRNAs for two specific epithelial markers, carcinoembryonic antigen (CEA) and cytokeratin 20 (CK-20), we examined 34 gastric cancer patients who had been histologically diagnosed and 22 patients had undergone serosal and peritoneal brushing. RESULTS: In 10 (29.4%) of the 34 gastric cancer patients, we detected CK20 mRNA before manipulation, and in 17 (51.5%) of those patients, after we detected it. The density of the CK20 mRNA band was increased in 11 cases (33.3%) and the density was decreased in 2 cases (6.1%). In 16 (48.5%) of the 34 gastric cancer patients, we detected CEA mRNA before manipulation, and in 17 (51.5%) patients after we detected it. The density of the CEA mRNA band was increased in 8 cases (24.2%) and decreased in 3 cases (9.1%). CONCLUSION: These result suggest that the "no-touch isolation technique" might be useful when operating on advanced gastric cancer patients and that serosal or Douglas pouch brushing can be used to determine the status of micrometastasis.

Use of RT-PCR for CK20 and CEA mRNA to Detect of Micrometastasis in the Draining Venous Blood and the Peritoneum in Gastric Cancer Patients

PURPOSE: The benefits of the "no-touch" isolation technique that is usually performed to prevent the circulation of tumor cells are not evident. The aim of this study was to determine whether the no-touch isolation technique for treating gastrointestinal cancers could prevent the circulation of tumor cells detected by reverse transcriptase polymerase chain reaction (RT-PCR). Matrials and Methods: By using RT-PCR to amplify mRNAs for two specific epithelial markers, carcinoembryonic antigen (CEA) and cytokeratin 20 (CK-20), we examined 34 gastric cancer patients who had been histologically diagnosed and 22 patients had undergone serosal and peritoneal brushing. RESULTS: In 10 (29.4%) of the 34 gastric cancer patients, we detected CK20 mRNA before manipulation, and in 17 (51.5%) of those patients, after we detected it. The density of the CK20 mRNA band was increased in 11 cases (33.3%) and the density was decreased in 2 cases (6.1%). In 16 (48.5%) of the 34 gastric cancer patients, we detected CEA mRNA before manipulation, and in 17 (51.5%) patients after we detected it. The density of the CEA mRNA band was increased in 8 cases (24.2%) and decreased in 3 cases (9.1%). CONCLUSION: These result suggest that the "no-touch isolation technique" might be useful when operating on advanced gastric cancer patients and that serosal or Douglas pouch brushing can be used to determine the status of micrometastasis.

The Expressions of Cytokeratin 7 and 20 in Epithelial Tumors: A Survey of 91 Cases / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: This study was performed to determine the expressions of cytokeratin 7 and cytokeratin 20 in epithelial neoplasms, and to investigate their potential role in the differential diagnosis of carcinomas of various organs. MATERIALS AND METHODS: We investigated 91 various cases of primary and metastatic cancers, using a panel of commercially available monoclonal antibodies against cytokeratins 7 and 20 (CK7 and CK20), by immunohistochemistryand an avidin-biotin immunoperoxidase technique. The specimens were formalin-fixed and paraffin- embedded, and examined using 4micrometer thick serial sections. RESULTS: The expression of CK7 was seen in the majority of carcinoma cases, including transitional cell carcinomas (100%), pulmonary adenocarcinomas (100%), ovarian serous adenocarcinomas (100%), cholangiocarcinomas (70%), colonic adenocarcinomas (64.29%) and invasive ductal carcinomas (60%). The expression of CK20 was seen in the majority of colorectal carcinomas cases (85.72%), but was virtually absent in pulmonary adenocarcinomas (0%), uterine cervical carcinomas (0%), ovarian carcinomas (0%), prostatic adenocarcinomas (0%), adenocarcinomas of the gall bladder (0%) and cholangiocarcinomas (12.5%). CONCLUSION: In the all cases investigated, either CK7 or CK20 immunophenotypes were conserved in the tumor cells of primary tumors and in those of the corresponding metastatic lesions. It is suggested that CK7/CK20 immunophenotyping, in metastatic carcinomas of an unknown origin, maybe useful in the determination of the primary site of the metastasis.

Utility of Thyroid Transcription Factor-1 and Cytokeratin 20 in Identifying the Origin of Metastatic Carcinomas of Cervical Lymph Nodes

The identification of primary location of a metastatic tumor is a difficult diagnostic problem and sometimes can be facilitated by the use of immunohistochemical markers. Thyroid transcription factor-1 (TTF-1) is a 38-kDa nuclear homeodomain transcription factor that is expressed specifically in lung or thyroid neoplasms. Cytokeratin 20 (CK20) is a 46-kDa low-molecular-weight cytokeratin that shows restricted expression in adenocarcinomas of the gastrointestinal tract (GIT) and transitional cell carcinomas of the urinary tract. We studied the immunohistochemical expression of TTF-1 and CK20 in 68 metastatic carcinomas in cervical lymph nodes. The primary sites were the lung in 29 cases, stomach in 13, colorectum in 3, and other sites in 23. TTF-1 expression was detected in 69.0% of metastatic lung carcinomas and none in metastatic GIT carcinomas, whereas CK20 expression was detected in 68.8% of metastatic GIT carcinomas and none of metastatic lung carcinomas. TTF-1 had a specificity of 0.95 and a sensitivity of 0.69 for metastatic lung carcinoma, whereas CK20 had a specificity of 1.00 and a sensitivity of 0.69 for metastatic GIT carcinoma. These results indicate that TTF-1 and CK20 should be the first choice as a component of antibody panel to prove or to exclude the lung and GIT origin, respectively, especially in patients presenting with metastatic carcinomas of unknown primary site.

Detection of peritoneal micrometastases of gastric cancer and its clinical significance / 中国普通外科杂志

Objective To evaluate the clinical significance of the intraoperative detection of peritoneal micrometastases of gastric cancer.Methods In selected 50 cases of gastric cancer in which no obvious peritoneal metastasis was found preoperatively or during laparotomy,Douglas′s pouch peritoneal biopsy was undertaken intraoperatively,then HE and CK-20 immunohistochemistry staining of the specimens was performed.The expression of CK-20 mRNA in peritoneal irrigation fluid was also determined by RT-PCR.Results HE staining of all cases was negative.The positive rate of CK-20 immunohistochemistry staining was 24.0 %(12/50),and 36.0 %(18/50) with RT-PCR method.The positive rate of CK-20 mRNA was significantly related with the histological type,the depth of invasion and the number of lymph node metastasis(P

Study of Cytokeratin 20 Expression and p53 Gene Mutation in Peripheral Blood of Patients with Colorectal Carcinoma / 中国医师杂志

Objective To set up an efficient and rapid method for detecting CK20 expression in peripheral blood of patients with colorectal carcinoma, and explore the relationship between CK20 expression and micrometastasis of colorectal carcinoma. Methods CK20 mRNA expression in peripheral blood of 36 patients with colorectal carcinomas was detected at various time points before and after operation by fluorescent RT-PCR. The mutation of p53 gene was also detected using SSCP. Results The positive rate of CK20 mRNA expression in peripheral blood before and 24 hours after operation was 75%(27/36) and 83.3%(30/36), respectively. After the short-term chemotherapy, the positive rate of CK20 mRNA expression was 36%(13/36). No mutation of p53 gene was found in those patients. Conclusion Fluorescent RT-PCR for detecting CK20 mRNA expression in peripheral blood was simple and efficacious. It was useful to monitor micrometastasis of colorectal carcinoma.