Spread of colorectal cancer micrometastases in regional lymph nodes by reverse transcriptase-polymerase chain reactions for carcinoembryonic antigen and cytokeratin 20

Comparison of conventional unstained lymph nodal harvesting vs methylene blue-stained lymph nodal harvesting in colorectal specimen in staging left-sided colorectal carcinoma: a randomized controlled trial

BACKGROUND

The management and prognosis of colorectal carcinomas (CRCs) are related to the stage of the disease, which, in turn, relies on the lymph node harvest from the surgical specimen. The guidelines recommend that at least 12 lymph nodes are required, which is not achieved in most resections. In this study, we propose a method to improve the lymph node yield in such cases. This study aimed to determine whether ex vivo injection of methylene blue into the inferior mesenteric artery or its branches improves lymph node retrieval in left-sided CRCs.

METHODS

This study was conducted as a single-center, double-blinded, superiority randomized controlled trial. Patients who underwent elective surgery for left-sided CRCs with curative intent were randomized into 2 groups: stained and unstained. The sample size was calculated as 66. In all patients, details of disease stage, history of neoadjuvant therapy, and number of isolated lymph nodes were recorded.

RESULTS

The mean number of lymph nodes extracted from the stained group was significantly higher than that from the unstained group (15.9 ± 5.2 vs 9.1 ± 5.7, respectively; P < .001). Among the patients who had received neoadjuvant therapy, the yield was higher in the stained group (P < .001). The yield was found to be greater in patients who had undergone upfront surgery than in those who had undergone neoadjuvant therapy, even in the stained group (100% vs 66.7%, respectively).

CONCLUSION

The use of methylene blue injection into resected specimens of left-sided CRCs significantly improved the lymph node yield.

Micrometastasis in lymph nodes of colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide. Postoperative adjuvant chemotherapy is recommended for node‐positive stage III patients. A systematic meta‐analysis reported that the presence of micrometastases in regional lymph nodes (LNs) was associated with poor survival in patients with node‐negative CRC. Because most data employed in the meta‐analysis were based on retrospective studies, we conducted a prospective clinical trial and concluded that stage II is a transitional zone between stage I and stage III, where CRC tumors continuously increase the micrometastasis volume in LNs and proportionally raise the risk for tumor recurrence. The one‐step nucleic acid amplification (OSNA) assay is a simple and rapid technique to detect CK19 mRNA using the reverse‐transcription loop‐mediated isothermal amplification (RT‐LAMP) method. Using the OSNA assay, we and colleagues reported that the upstaging rates of pStages I, IIA, IIB, and IIC were 2.0%, 17.7%, 12.5%, and 25%, respectively, in 124 node‐negative patients. Survival analysis indicated that OSNA positive stage II CRC patients had a shorter 3‐y disease‐free survival rate than OSNA negative stage II CRC patients. In 2017, AJCC TNM staging (the 8th version) revised the definition of LN metastasis in colon cancer and it is stated that micrometastasis should be considered as a standard LN metastasis. To our surprise, this revision was based on a meta‐analysis to which our previous study on micrometastasis largely contributed. The remaining questions to be addressed are how to find micrometastases efficiently and whether postadjuvant chemotherapy is effective to prevent disease recurrence and to contribute to longer survival.

Red-emitting FIT-PNAs: "On site" detection of RNA biomarkers in fresh human cancer tissues

To date, there are limited approaches for the direct and rapid visualization (on site) of tumor tissues for pathological assessment and for aiding cytoreductive surgery. Herein, we have designed FIT-PNAs (forced-intercalation-peptide nucleic acids) to detect two RNA cancer biomarkers. Firstly, a lncRNA (long noncoding RNA) termed CCAT1, has been shown as an oncogenic lncRNA over-expressed in a variety of cancers. The latter, an mRNA termed KRT20, has been shown to be over-expressed in metastases originating from colorectal cancer (CRC). To these FIT-PNAs, we have introduced the bis-quinoline (BisQ) cyanine dye that emits light in the red region (605-610 nm) of the visible spectrum. Most strikingly, spraying fresh human tissue taken from patients during cytoreductive surgery for peritoneal metastasis of colon cancer with an aqueous solution of CCAT1 FIT-PNA results in bright fluorescence in a matter of minutes. In fresh healthy tissue (from bariatric surgeries), no appreciable fluorescence is detected. In addition, a non-targeted FIT-PNA shows no fluorescent signal after spraying this FIT-PNA on fresh tumor tissue emphasizing the specificity of these molecular sensors. This study is the first to show on-site direct and immediate visualization of an RNA cancer biomarker on fresh human cancer tissues by topical application (spraying) of a molecular sensor.

Immunohistochemistry and Reverse Transcriptase Polymerase Chain Reaction on Sentinel Lymph Nodes can Improve the Accuracy of Nodal Staging in Breast Cancer Patients

In this study the nodal staging sensitivity of sentinel lymph node biopsy (SLNB) with detailed pathological and molecular biological examination has been investigated and compared to that of axillary lymph node dissection (ALND) with routine histological evaluation. Sentinel lymph nodes (SLNs) were removed by the dual-agent injection technique in 68 patients with primary, clinically node-negative breast cancer. Forty-seven patients had negative SLNs according to hematoxylin and eosin (H&E) staining. These H&E-negative SLNs were serially sectioned and examined at 250 μm levels by anticytokeratin immunohistochemistry (IHC). In 14 patients the SLNs were also investigated by cytokeratin 20 (CK20) reverse transcriptase polymerase chain reaction (RT-PCR). SLNB with IHC increased the node-positive rate by 26% (by 40% in tumors less than or equal to 2 cm in size (pT1) and by 9% in tumors more than 2 cm but less than or equal to 5 cm in size (pT2)). The sensitivity of SLNB with IHC was superior to that of ALND with routine histology in pT1 tumors and identical in pT2 tumors. The concordance between histology and RT-PCR was only 21%, and in two of three cases with positive histological results RT-PCR was negative. In conclusion, SLNB with detailed pathological and/or molecular biological evaluation can improve the sensitivity of regional staging. ALND can probably be abandoned in patients with pT1 SLN-negative breast cancer. Further prospective studies are required to determine the clinical significance of these detailed SLN evaluation techniques, but at present these methods are still investigational.

Lymph node micrometastasis in gastrointestinal tract cancer--a clinical aspect

Lymph node micrometastasis (LNM) can now be detected thanks to the development of various biological methods such as immunohistochemistry (IHC) and reverse transcription-polymerase chain reaction (RT-PCR). Although several reports have examined LNM in various carcinomas, including gastrointestinal (GI) cancer, the clinical significance of LNM remains controversial. Clinically, the presence of LNM is particularly important in patients without nodal metastasis on routine histological examination (pN0), because patients with pN0 but with LNM already in fact have metastatic potential. However, at present, several technical obstacles are impeding the detection of LNM using methods such as IHC or RT-PCR. Accurate evaluation should be carried out using the same antibody or primer and the same technique in a large number of patients. The clinical importance of the difference between LNM and isolated tumor cells (≤0.2 mm in diameter) will also be gradually clarified. It is important that the results of basic studies on LNM are prospectively introduced into the clinical field. Rapid diagnosis of LNM using IHC and RT-PCR during surgery would be clinically useful. Currently, minimally invasive treatments such as endoscopic submucosal dissection and laparoscopic surgery with individualized lymphadenectomy are increasingly being performed. Accurate diagnosis of LNM would clarify issues of curability and safety when performing such treatments. In the near future, individualized lymphadenectomy will develop based on the establishment of rapid, accurate diagnosis of LNM.

Upstaging of early colorectal cancers following improved lymph node yield after methylene blue injection

AIMS

To evaluate whether the use of intra-arterial methylene blue injection improves lymph node yield, and to determine whether a higher lymph node count results in upstaging in colorectal cancer.

METHOD AND RESULTS

We performed a retrospective study of colorectal cancer specimens (n = 234) 1 year after implementation of the method. All colorectal cancer specimens from the previous year served as our control group. Data concerning tumour characteristics, lymph node count, number of positive lymph nodes and success of methylene injection had been prospectively collected in accordance with the department's ongoing registration. The method was easy to implement and perform with a high rate of success (86%). The number of identified lymph nodes was highly significantly improved in the study group (P < 0.0001). In resections with pT1/T2 tumours, we demonstrated a significant increase in the number of resection specimens containing positive lymph nodes, with an increase in pN1 resections from 9.4% in the control group to 26.7% in the study group (P = 0.04).

CONCLUSIONS

THE methylene blue technique significantly improves lymph node identification in colorectal cancer specimens, and the improved lymph node identification leads to upstaging of International Union Against Cancer (UICC) pT1/pT2 cancers.

Pathological evaluation of mesocolic resection quality and ex vivo methylene blue injection: what is the impact on lymph node harvest after colon resection for cancer?

BACKGROUND

Although the National Quality Forum has endorsed the harvest of ≥12 lymph nodes as a standard quality indicator for colon cancer surgery, this minimum quantity is not reached in many centers.

OBJECTIVE

The aim of this study was to assess the impact of the implementation of a mesocolon evaluation pathological protocol and ex vivo arterial methylene blue injection on the number of nodes harvested after colon cancer resection.

DESIGN

A prospective series was compared with a historical group.

SETTINGS

This study was conducted by a specialized colorectal multidisciplinary team at a tertiary teaching hospital.

PATIENTS

From June 2009 to December 2009, all the specimens after colon resection for cancer were analyzed with the use of a "mesocolon quality pathological evaluation" protocol. Moreover, a consecutive series of specimens was analyzed after arterial ex vivo injection of methylene blue. We compared the study groups with our previous series (2005-2009).

INTERVENTIONS

The "mesocolon quality pathological evaluation" protocol was used with or without arterial methylene blue ex vivo injection.

MAIN OUTCOME MEASURE

The primary outcome measure was the number of lymph nodes harvested.

RESULTS

The mean number (SD) of lymph nodes collected was 20.6 (10.5), 37.1 (12.8), and 47.6 (12.9) (p < 0.0001) in the control, protocol, and methylene blue groups. In the control group, the minimum number of 12 and 18 lymph nodes collected was not reached in 92 (15.9%) and 258 (44.6%) patients. In contrast, all patients in the protocol and methylene blue groups had more than 18 lymph nodes collected. The multivariate analysis confirmed the application of the "mesocolon quality pathological evaluation" protocol and the methylene blue ex vivo injection, along with the type of resection and the length of the specimen, to be independent factors determining the number of nodes collected.

LIMITATIONS

The patients are not randomly selected and are compared with a retrospective series.

CONCLUSION

The implementation of a "mesocolon quality pathological evaluation" protocol along with the arterial ex vivo injection of methylene blue can significantly increase the number of nodes isolated after colonic resection, reaching a 100% rate of specimens with more than 12 nodes.

NM23 protein expression in colorectal carcinoma using TMA (tissue microarray): association with metastases and survival

CONTEXT

NM23, a metastasis suppressor gene, may be associated with prognosis in patients with colorectal carcinoma.

OBJECTIVE

To analyze NM23 expression and its association with the presence of lymph node and liver metastases and survival in patients operated on for colorectal carcinoma.

METHODS

One hundred thirty patients operated on for colorectal carcinoma were investigated. Tissue microarray blocks containing neoplastic tissue and tumor-adjacent non-neoplastic mucosa were obtained and analyzed by immunohistochemical staining using a monoclonal anti-NM23 antibody. Immunohistochemical expression was assessed using a semiquantitative scoring method, counting the percentage of stained cells. The results were compared regarding morphological and histological characteristics of the colorectal carcinoma, presence of lymph node and liver metastases, tumor staging, and patient survival. Statistical analysis was performed using the Mann-Whitney test, the Kruskal-Wallis test and Fisher's exact test. Survival analysis was performed using the Kaplan-Meier method and the log-rank test.

RESULTS

NM23 expression was higher in colorectal carcinoma tissue than in adjacent non-neoplastic mucosa (P<0.0001). NM23 protein expression did not correlate with degree of cell differentiation (P = 0.57), vascular invasion (P = 0.85), lymphatic invasion (P = 0.41), perineural infiltration (P = 0.46), staging (P = 0.19), lymph node metastases (P = 0.08), or liver metastases (P = 0.59). Disease-free survival showed significant association (P = 0.01) with the intensity of NM23 protein immunohistochemical expression in colorectal carcinoma tissue, whereas overall survival showed no association with NM23 protein expression (P = 0.13).

CONCLUSIONS

NM23 protein expression was higher in neoplastic colorectal carcinoma tissue than in adjacent non-neoplastic mucosa, showing no correlation with morphological aspects, presence of lymph node or liver metastases, colorectal carcinoma staging, or overall survival. Disease-free survival was higher in patients with increased NM23 expression.

CpG-island methylation of the ER promoter in colorectal cancer: analysis of micrometastases in lymph nodes from UICC stage I and II patients

Patients with UICC stage II colorectal cancer (CRC) have a risk of approximately 20% to develop disease recurrence after tumour resection. The presence and significance of micrometastases for locoregional recurrence in these patients lacking histopathological lymph node involvement on routine stained HE sections is undefined. Oestrogen receptor (ER) promoter methylation has earlier been identified in CRC. Therefore, we evaluated the methylation status of the ER promoter in lymph nodes from 49 patients with CRC UICC stage I and II as a molecular marker of micrometastases and predictor of local recurrence. DNA from 574 paraffin-embedded lymph nodes was isolated and treated with bisulphite. For the detection of methylated ER promoter sequences, quantitative real-time methylation-specific PCR was used. Of the 49 patients tested, 15 (31%) had ER methylation-positive lymph nodes. Thirteen of those (86%) remained disease free and two (14%) developed local recurrence. In the resected lymph nodes of 34 of the 49 patients (69%), no ER promoter methylation could be detected and none of these patients experienced a local relapse. The methylation status of the ER promoter in lymph nodes of UICC stage I and II CRC patients may be a useful marker for the identification of patients at a high risk for local recurrence.

Sentinel lymph node evaluation is technically feasible and may improve staging in colorectal cancer

PURPOSE

The accurate nodal staging of colorectal cancer (CRC) is important to identify those patients who may benefit from adjuvant chemotherapy. Some have suggested that identification of sentinel lymph nodes (SLN) may improve staging in CRC. We sought to determine: the feasibility of identifying SLN in CRC utilizing isosulfan blue dye; the accuracy of the identified SLN in predicting the status of the remainder of the lymph nodes in CRC; and whether a more thorough evaluation of SLN with serial step sectioning and immunohistochemistry would more accurately stage patients with CRC.

METHODS

A pilot trial was initiated at Walter Reed Army Medical Center (WRAMC), and 17 patients with masses on colonoscopy and subsequent tissue diagnosis of CRC were enrolled. Patients underwent standard surgical resection of their CRC with wedge of mesentery containing draining lymph nodes. Isosulfan blue dye was injected around the tumor subserosally/submucosally before dividing the mesenteric portion of the resection (n = 7) or ex vivo (n = 10). Sentinel lymph nodes were defined as all nodes staining blue and were dissected from the mesentery in the operating room. The SLN were sent separately for standard bivalving and hematoxylin and eosin staining (H&E) followed by serial step sectioning and immunohistochemistry (IHC) staining for cytokeratin.

RESULTS

Seventeen patients (6 men, 11 women) were enrolled. The average preoperative carcinoembryonic antigen (CEA) was 5.9 (range, 1.2 to 18.9), and the average postoperative CEA was 2.8 (range, 0.7 to 9.1). One patient had a T1 tumor, 6 patients had T2 tumors, and 10 patients had T3 tumors on final pathology. Five cancers were well differentiated, 11 were moderately differentiated, and 1 was poorly differentiated. In all 17 cases, SLN were identified. A mean of 5.5 SLN was found per specimen (range, 2 to 11) with no difference noted between injection techniques (in vivo vs ex vivo). An additional 12 nonsentinel lymph nodes (range, 1 to 29) were identified per specimen. Ten patients had negative SLN and non-SLN. Seven patients were found to have positive SLN (3 by H&E, 2 by serial step sectioning, and 2 by IHC only).

CONCLUSIONS

The isosulfan blue technique is technically feasible to allow identification of sentinel lymph nodes. In this study, no false-negative SLN occurred. A total of 7 patients had positive SLN; more importantly, 4 patients were upstaged as a result of serial step sectioning and immunohistochemistry staining. We hypothesize that this method may help pathologists find appropriate lymph nodes for more detailed analysis. As a result, patients may be more accurately staged and counseled for adjuvant chemotherapy, which has been shown to improve survival in node-positive CRC. Further studies should be undertaken to test these preliminary findings.

Detection of disseminated tumor cells in the lymph nodes of colorectal cancer patients using a real-time polymerase chain reaction assay

INTRODUCTION

Postoperative treatment for colorectal cancer depends on tumor stage as defined by the International Union Against Cancer (UICC). Adjuvant chemotherapy is not recommended in patients without lymph node involvement (UICC stages I and II). As many as 20-30% of these patients, however, will develop recurrence.

AIMS AND OBJECTIVES

We conducted this study to determine the presence of disseminated tumor cells in the lymph nodes by quantitative real-time polymerase chain reaction (QRT-PCR) for cytokeratin 20 (CK20) in an attempt to provide supplementary information compared to histopathological findings.

MATERIALS AND METHODS

Using a standard QRT-PCR assay, we examined primary tumors and 391 lymph nodes from 31 patients with completely resected colorectal cancer.

RESULTS

Of the 31 primary tumors, 29 were positive for CK20 by QRT-PCR.

DISCUSSION

An examination of the lymph nodes from the 29 patients with CK20-positive primary tumors revealed that 35 (92.1% sensitivity) of the 38 histopathologically positive lymph nodes and 54 (16.7%) of the 324 histopathologically negative lymph nodes were positive by molecular analysis. CK20 expression was detected in 10 (100%) of 10 patients with a histopathologically positive lymph node status (pN1). In 9 (47.4%) of 19 patients with negative histopathological results (pN0), we detected a CK20 mRNA signal in at least one lymph node. Whereas eight patients with histopathologically negative lymph nodes could be upstaged on the basis of the molecular findings, no patient would be downstaged.

CONCLUSION

Our results suggest that QRT-PCR for CK20 is a useful tool for the quantitative detection of micrometastases in the regional lymph nodes. We introduce a standardized procedure that integrates a molecular diagnostic technique in the clinical staging.

Combination analysis of a whole lymph node by one-step nucleic acid amplification and histology for intraoperative detection of micrometastasis

OBJECTIVE

The aim was to develop a more efficient molecular detection system than histological examination (HE) for lymph node (LN) metastasis.

METHODS

Cytokeratin (CK) 19 mRNA copy numbers of 5 colon carcinoma cell lines (Lovo, DLD1, WiDr, Colo201 and Colo320) were calculated and compared by one-step nucleic acid amplification (OSNA) and conventional real-time reverse-transcription polymerase chain reaction (RT-PCR). Then, 91 LN submitted for HE from 6 patients with advanced colorectal adenocarcinoma and 64 LN submitted for frozen diagnosis from 47 patients with different malignancies were examined by OSNA and HE.

RESULTS

CK19 mRNA copy numbers of all but Colo320 cells detected by OSNA were within double of those detected by RT-PCR. The least cell count of Lovo cells detected at one reaction (2 microl) by OSNA was calculated as 0.8 cells. Carcinoma metastasis showing either HE+ or OSNA+ was detected in 7.9% of the LN from advanced colorectal adenocarcinomas and in 30.0% of the LN for frozen diagnosis from different malignancies; HE-/OSNA+ metastasis was detected in 4.8 and 4.0%, respectively. OSNA analysis of 1 LN could be completed within 40 min.

CONCLUSION

A combined analysis of LN by HE and OSNA could increase the sensitivity for detecting micrometastasis during surgery.

RT-PCR and immunohistochemical evaluation of sentinel lymph nodes after in vivo mapping with Patent Blue V in colon cancer patients

OBJECTIVE

Lymph node status is the most important predictive factor in the treatment of colorectal cancer. As sentinel lymph node (SLN) biopsy might upstage stage II colon cancer, it could have therapeutic consequences in the future. We investigated the feasibility of in vivo SLN detection with Patent Blue V dye and evaluated nodal microstaging and ultrastaging using cytokeratin immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR).

MATERIAL AND METHODS

In 30 consecutive patients operated on for colon cancer, subserosal injection with Patent Blue dye was used for SLN detection in four different hospitals under the supervision of one regional coordinator. In searching for occult micrometastases, each SLN was examined at three levels. In tumor-negative SLNs at routine hematoxylin-eosin (H&E) examination (pN0) we performed CK8/CK18 immunohistochemistry (IHC) and RT-PCR for carcinoembryonic antigen (CEA).

RESULTS

The procedure was successful in 29 out of 30 patients (97%). The SLN was negative in 18 patients detected by H&E and IHC. In 16 patients the non-SLN was also negative, leading to a negative predictive value of 89% and an accuracy of 93%. Upstaging occurred in 10 patients (33%) - 7 by IHC and 3 by RT-PCR. Aberrant lymphatic drainage was seen in 3 patients (10%).

CONCLUSIONS

The SLN concept in colon carcinoma using Patent Blue V is feasible and accurate. It leads to upstaging of nodal status in 33% of patients when IHC and PCR techniques are combined. Therefore, the clinical value of SLN should be the subject of further studies.

Identification of early-stage colorectal cancer patients at risk of relapse post-resection by immunobead reverse transcription-PCR analysis of peritoneal lavage fluid for malignant cells

PURPOSE

Colorectal cancer patients diagnosed with stage I or II disease are not routinely offered adjuvant chemotherapy following resection of the primary tumor. However, up to 10% of stage I and 30% of stage II patients relapse within 5 years of surgery from recurrent or metastatic disease. The aim of this study was to determine if tumor-associated markers could detect disseminated malignant cells and so identify a subgroup of patients with early-stage colorectal cancer that were at risk of relapse.

EXPERIMENTAL DESIGN

We recruited consecutive patients undergoing curative resection for early-stage colorectal cancer. Immunobead reverse transcription-PCR of five tumor-associated markers (carcinoembryonic antigen, laminin gamma2, ephrin B4, matrilysin, and cytokeratin 20) was used to detect the presence of colon tumor cells in peripheral blood and within the peritoneal cavity of colon cancer patients perioperatively. Clinicopathologic variables were tested for their effect on survival outcomes in univariate analyses using the Kaplan-Meier method. A multivariate Cox proportional hazards regression analysis was done to determine whether detection of tumor cells was an independent prognostic marker for disease relapse.

RESULTS

Overall, 41 of 125 (32.8%) early-stage patients were positive for disseminated tumor cells. Patients who were marker positive for disseminated cells in post-resection lavage samples showed a significantly poorer prognosis (hazard ratio, 6.2; 95% confidence interval, 1.9-19.6; P = 0.002), and this was independent of other risk factors.

CONCLUSION

The markers used in this study identified a subgroup of early-stage patients at increased risk of relapse post-resection for primary colorectal cancer. This method may be considered as a new diagnostic tool to improve the staging and management of colorectal cancer.

Detection of occult tumor cells in lymph nodes from non-small cell lung cancer patients using reverse transcription-polymerase chain reaction for carcinoembryonic antigen mRNA with the evaluation of its sensitivity

We evaluated the usefulness of a real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) method for detecting occult tumor cells in histologically malignant-negative lymph nodes resected from patients with non-small cell lung cancer. First, we examined the relationship between tumor cell number and carcinoembryonic antigen (CEA) mRNA copy number using a PCR method with a cancer cell line (A549) in a serial dilution study. Next, we evaluated the relationship between nodal metastatic area size and CEA mRNA copy number using lymph nodes with histologically proven metastasis in a serial slice study. On the basis of those results, we performed RT-PCR analyses with 28 primary tumors and 211 lymph nodes from 28 patients who underwent a lobectomy with systematic node dissection. Our results in the serial dilution study showed that the detectable limitation by quantitative RT-PCR was 25-100 neoplastic cells and 20-100 CEA mRNA copy numbers. In the serial slice study, we found a correlation between CEA mRNA copy number and nodal metastatic area. In the clinical samples, amplification of CEA mRNA was obtained with all 28 primary tumors and 13 of the lymph nodes with metastasis shown by hematoxylin-eosin staining. Furthermore, 52 (25%) of 211 histologically negative lymph nodes and the specimens from 14 (64%) of the 22 pN0 patients revealed a significant level of CEA mRNA. These results indicate that micrometastases, which are not detectable with conventional examinations, can be detected by the present method of RT-PCR for CEA mRNA in a proportion of patients with resected pN0 non-small cell lung cancer.

Discordant quantitative detection of putative biomarkers in nodal micrometastases of colorectal cancer: biological and clinical implications

AIMS

Nodal expression of the carcinoembryonic antigen (CEA), cytokeratin 20 (CK20), and guanylyl cyclase C (GCC) genes was measured in tandem in patients with colorectal cancer (CRC) to assess whether there would be sufficient agreement between these markers in their ability to detect micrometastasis to qualify one of them as a universal marker, and whether frozen and paraffin wax embedded tissues would yield similar results.

METHODS

One hundred and seventy five frozen lymph nodes (FT) and 158 formalin fixed, paraffin wax embedded lymph nodes (PET) from 28 CRC cases were analysed using gene specific quantitative real time polymerase chain reaction, carried out on the LightCycler system with SYBR Green chemistry.

RESULTS

There was significant disparity in positive detection of the three biomarkers in FT versus PET, with notable agreement achieved only for CEA (66.6%) in FT versus PET in Dukes' B disease, and between CK20 and GCC (44.6%) in FT, also in Dukes' B disease. One patient with full concordance in all three tumour markers with both tissue types suffered a relapse and died within two years of follow up.

CONCLUSIONS

There was considerable discordance in the positive detection of the three tumour markers in both tissue types (FT versus PET). This brings into question whether using a single tumour marker to detect micrometastasis in one tissue type (FT or PET) is adequately representative, and challenges the concept of universal markers for molecular CRC metastatic detection. Multiple tumour markers would predict more accurately the metastatic potential of Dukes' B CRCs.

The impact of bone marrow micrometastases on metastatic disease-free survival in patients with colorectal carcinoma

AIMS

The biological relevance of bone marrow micrometastases (BMM) in colorectal cancer remains unknown. Here, we investigate their nature by examining the impact of the presence of BMM on metastatic disease-free survival in a cohort of patients with this disease.

METHODS

Sixty-three consecutive patients undergoing surgery for colorectal cancer of any stage were studied after approval of the study protocol by the local ethics committee and with full individual informed consent. All had bilateral iliac crest bone marrow aspirates prior to operation. Aspirates were then examined for the presence of aberrant cytokeratin-18-positive cells by a blinded observer using both flow cytometric and APAAP immunohistochemical techniques.

RESULTS

Mean follow-up after surgery was 4.6 years (range 1.9-6.9) for those without hepatic metastases at diagnosis. Seven of 34 patients with Dukes' stage A or B developed metastatic disease after a mean interval of 4.7 years (range 3.8-6.8). However, only 2 of these patients demonstrated BMM at the time of surgery. Nine of 15 patients with Dukes' C carcinoma at the time of surgery subsequently developed metastases after a mean interval of 4.4 years (range 1.9-6.9). Again, only two of these patients had BMM detectable initially. In only three of the 14 patients known to have metastases at the time of operation (i.e. Dukes''D' disease) were BMM found.

CONCLUSION

The presence of BMM as detected by this methodology was not predictive of tumour recurrence or metastasis. This study does not support the consideration of adjuvant therapy based on the presence of BMM at a single pre-operative time point in patients with colorectal cancer.

Molecular detection of clinical colorectal cancer metastasis: how should multiple markers be put to use?

BACKGROUND AND AIMS

Up to 45% of colorectal cancer (CRC) patients will develop local recurrence or metastasis following curative resection. The latter is due to cells shed from the primary carcinoma prior to or during surgery. The aim of this study was to contribute toward a "rational"-approach for detecting these disseminated tumor cells (DTC) using a combination of independent markers and detection methods.

PATIENTS/METHODS

Liver, lymph node, and bone marrow samples from 246 CRC patients were screened for DTC using three markers: mutated K-ras was detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and cytokeratin 20 (CK20) and guanylylcyclase C (GCC), indicating circulating epithelial cells, were tracked by nested reverse-transcription (RT) PCR.

RESULTS

The rate of positive findings of the individual markers (CK20: 88%; GCC: 88%; K-ras: 67%) and their combinations (88-50%) was significantly higher in biopsies from liver metastases than in liver samples from patients without evident distant metastasis (M0; p<0.03). The detection rate of individual markers (except GCC) was also significantly elevated in inconspicuous liver tissue adjacent to metastasis compared with specimens from M0 patients. When using the concomitant detection of all three markers as criterion for DTC in the liver of M0 patients, however, no patient was DTC-positive. Therefore, the concomitant presence of the two CEC markers (CK20 plus GCC) and/or the presence of mutated K-ras were preferred for a combined evaluation, which resulted in a 24% detection rate for biopsies from both liver lobes. This translates into 39% of M0 patients with at least one positive liver biopsy.

CONCLUSION

Our results suggest that the concomitant detection of CK20 plus GCC and/or the presence of mutated K-ras are a rational approach for tracking CEC/DTC in CRC patients.

Quantification of colorectal cancer micrometastases in lymph nodes by nested and real-time reverse transcriptase-PCR analysis for carcinoembryonic antigen

PURPOSE

Reverse-transcriptase PCR (RT-PCR) assays for carcinoembryonic antigen (CEA) have been described to identify lymph node micrometastases. These assays are not quantitative and can be confounded by false-positive results. The purpose of this study was to determine whether quantification of CEA in lymph nodes could more readily identify clinically relevant groups.

EXPERIMENTAL DESIGN

Specimens included 400 lymph nodes from 64 patients undergoing colon resections. Specimens were tested by immunohistochemistry and by RT-PCR using nested primers for CEA. Specimens from 59 patients that were positive by nested RT-PCR were further quantified by detection of CEA mRNA fluorescence increase at a threshold PCR cycle.

RESULTS

CEA was detected by nested RT-PCR analysis in 4 of 34 (12%) nodes of nonneoplastic disease, 2 of 13 (15%) nodes from T(1)N(0) patients, 32 of 81 (40%) nodes of T(2)N(0) patients, 49 of 109 (45%) nodes from T(3)N0 patients, and 92 of 163 (56%) nodes from T(1-4)N(1-2) patients. The overall presence of any RT-PCR-detectable CEA in nodes did not differentiate patient groups. Immunohistochemistry was positive in nodes from 7% of T(3)N(0) patients and 100% of T(1-3)N(1-2) patients. CEA quantification revealed that 0 of 7 patients with nonneoplastic disease and 2 of 17 (12%) patients with stage I T(1-2)N(0) cancers had one or more lymph nodes with >/=1.0 x 10(2) CEA transcripts per sample. In contrast, 4 of 13 (31%) patients with stage II T(3)N(0) cancer and 10 of 22 (45%) stage III patients with known metastases had lymph nodes with >/=1.0 x 10(2) CEA transcripts.

CONCLUSIONS

These data suggest that quantification of CEA levels in lymph nodes may more accurately identify patients at risk for cancer recurrence than does routine nested RT-PCR or immunohistochemistry.

Lymphatic staging in colorectal cancer: pathologic, molecular, and sentinel node techniques

PURPOSE

Accurate staging in colorectal cancer is important to predict prognosis and identify patients who could benefit from adjuvant therapy. Patients with lymphatic metastasis, Stage III/Dukes C, are generally treated with adjuvant chemotherapy. Still, patients without lymphatic metastasis do have relapse as high as 27 percent in five years in Dukes B2. It is hypothesized that these patients have occult (micro)metastasis in their lymph nodes. If these (micro)metastasis can be identified, these patients might benefit from adjuvant therapy. We reviewed the literature on procedures to improve lymph node staging.

METHODS

An extensive literature search was performed in PubMed (www.pubmed.com). Using the reference lists, more articles were found.

RESULTS

We found 30 articles about sentinel node in colorectal cancer describing original series. Some groups reported several studies including the same patients. We reported their largest studies. For all other techniques, we only included key articles.

CONCLUSIONS

Many techniques to improve staging have been described. The finding of occult (micro)metastasis is of prognostic significance in most studies. The sentinel node technique has been recently described for use in colorectal cancer. Although it seems clear that this technique has prognostic potential, it is not yet been shown in a follow-up study. Furthermore, the finding of occult (micro)metastasis in any technique used has not been shown to be clinically significant. Whether to treat patients with adjuvant therapy if occult (micro)metastasis are found needs to be proven in future studies.

Detection of lymph node metastases of papillary thyroid cancer-comparison of the results of histopathology, immunohistochemistry and reverse transcription-polymerase chain reaction-a preliminary report

BACKGROUND

The range of lymphadenectomy in differentiated thyroid cancer remains still a matter of controversy because of the lack of reliable diagnostic methods for nodal metastases, other than histopathology.

AIM

To compare the results of detection of lymph node metastases of papillary thyroid cancer by conventional histopathology and immunohistochemistry with the results of reverse transcription-polymerase chain reaction for thyroglobulin mRNA.

PATIENTS AND METHODS

Each of 166 cervical lymph nodes obtained from 21 patients was divided into two halves: one was used for conventional histopathology and immunohistochemistry, the other part was investigated by molecular examination.

RESULTS

We obtained different results from examination of the lymph nodes in six (28.6%) patients. In four patients (19.1%) reverse transcription-polymerase chain reaction (RT-PCR) was more sensitive in detection of positive lymph nodes; in two patients (9.5%) it revealed fewer metastasised lymph nodes than did histopathology. The rest of the patients did not have any differences: 12 (57.1%) of them had negative lymph nodes and three (14.3%) had positive lymph nodes in all examinations.

CONCLUSIONS

(1) Thyroglobulin (Tg) RT-PCR is an appropriate method of detection for thyroid cancer cells. (2) In combination with histopathology, it might help to qualify patients' nodal status better.

Detection of lymph node micrometastasis in gastric cancer by MUC2 RT-PCR: usefulness in pT1 cases

BACKGROUND AND OBJECTIVES

The objectives of this study were to evaluate the clinical utility of MUC2-specific reverse transcriptase-polymerase chain reaction (RT-PCR) in gastric cancer patients and to compare MUC2-specific RT-PCR to carcinoembryonic antigen (CEA)-specific RT-PCR.

METHODS

A total of 305 lymph nodes from 28 patients with gastric cancer were histologically examined and analyzed by MUC2 RT-PCR and CEA RT-PCR.

RESULTS

MUC2 and CEA were expressed in 17.1 and 7.0% of the 286 histologically negative lymph nodes, respectively. The detection rate of MUC2 was significantly higher than that of CEA (P < 0.01). MUC2 RT-PCR revealed no false positive results in control specimens. Lymph node micrometastases in pT1 gastric cancer were expressed only in perigastric lymph nodes near the tumor and were not detected in tumor less than 30 mm in patients with mucosal cancer.

CONCLUSIONS

MUC2-specific RT-PCR is a sensitive and specific method to detect lymph node micrometastases in gastric cancer patients. The distribution of lymph node micrometastases detected by this method may be useful in minimally invasive procedures for gastric cancer, especially pT1 cases.

Sentinel lymph node mapping in colon cancer

BACKGROUND

By systematically reviewing the literature on sentinel lymph node mapping of colon cancers, this study aimed to evaluate this technique as it applies to colon cancers.

METHODS

Human studies on lymphatic mapping for colon cancers were reviewed. Multiple publications of the same studies, abstracts, and case reports were excluded. Current Contents, MEDLINE, EMBASE, and Cochrane Library databases were investigated.

RESULTS

Lymphatic mapping appears to be readily applicable to colon cancers, identifying lymph nodes most likely to harbor metastases. Identification of sentinel lymph nodes varied from 58% to 100% and carried a false-negative rate of approximately 10% in larger studies, but potentially rose 4% to 25% among patients representing a range from node-negative to node-positive (micrometastases) conditions. The prognostic implication of these micrometastases requires further evaluation. Lymphatic mapping in 6% to 29% of cases identified aberrant lymphatic drainage that altered the extent of the lymphadenectomy.

CONCLUSIONS

Further follow-up evaluation to assess the prognostic significance of micrometastases for colon cancers is required before the staging benefits of sentinel node mapping can have therapeutic implications. Lymphatic mapping offers the possibility of improving staging by identifying patients with early disseminated disease who should be considered for adjuvant treatment or included in trials of adjuvant treatment to speed up the breakthrough of more effective adjuvant regimens. Large studies are needed to determine whether the sentinel node concept is as valid for colon cancers as studies so far have shown it is for malignant melanoma and breast cancer.

Melanoma patient staging: histopathological versus molecular evaluation of the sentinel node

Lymphatic mapping and sentinel lymphadenectomy provide a minimally invasive means of directly determining the status of the regional lymph nodes in all patients who have a primary melanoma >1 mm thick but no clinical evidence of nodal involvement. Since the histological status of the sentinel node (SN) has been shown to be the most important prognostic factor in primary melanoma patients, the World Health Organization has recently recommended that sentinel lymphadenectomy should become the new standard of care for primary melanoma patients. This paper reviews the literature with regards to developments in and the current status of SN evaluation. Developments in the histopathological versus molecular detection of melanoma nodal metastases are reviewed, with specific emphasis on the strengths, limitations and clinical significance of these techniques. Molecular evaluation of the SN offers several advantages over standard histopathological analysis. These include an improved sensitivity, the cost-effective use of multiple markers for the improvement of detection rate and prognosis, as well as being less labour-intensive and costly. Moreover, molecular analysis has the potential to allow estimation of tumour burden. We review the potential causes of technical false-negative and false-positive reverse transcription-polymerase chain reaction (RT-PCR) results and how these could be eliminated by a systematic approach consisting of (i) careful and systematic assay design, which would include efficient tissue homogenization, choice of reagents and molecular markers, primer design and the use of one-stage versus two-stage PCR; (ii) careful optimization of the RT-PCR parameters (in particular the PCR cycle number) through the use of appropriate control tissues; and (iii) aiming for high assay reproducibility and lastly by applying the necessary positive and negative controls with each batch of samples. We also review the significant improvement in patient prognosis and management that has been made possible by the development of sentinel lymphadenectomy and histopathological evaluation of the SN, and compare the clinical (predictive) value of histopathological analysis with that of RT-PCR. Although RT-PCR is able to detect additional, clinically significant SN metastases that are missed by routine histopathology, its current limitation is that it overestimates the number of patients who have clinically significant melanoma metastases. Therefore, we suggest and discuss appropriate steps that need to be taken in order to minimize these false-positives and make this molecular tool more acceptable for routine clinical use.

Quantitative real-time RT-PCR for detection of disseminated tumor cells in peripheral blood of patients with colorectal cancer using different mRNA markers

The detection of disseminated tumor cells in peripheral blood from colorectal cancer patients by RT-PCR could be an attractive method for selecting patients for adjuvant therapy. We here report on real-time RT-PCR assays (LightCycler) to quantitate potential mRNA markers. We investigated specimens from colon carcinoma and normal colon mucosa tissues, cell lines, blood samples from 129 patients with colorectal cancer (all stages) and 58 reference blood samples (healthy donors, persons suffering from inflammatory bowel or infectious diseases). The expression profile in tissues showed high values for CEA and CK20, whereas in cell lines ProtM was predominant. All markers were detected in reference and patient blood samples (ProtM, 22, 17%; CEA, 84, 86%; CK20, 85, 88%). After quantitative analysis, the definition of cutoff values for each marker and the combination of markers, 13% of patients were judged to have elevated marker concentrations in their blood, from which only 6 had values significantly differing from cutoff value. There were no differences between stages of disease. In the case of 19 patients, investigated prior to and 1 week after surgery, 2 samples revealed a significant postoperative increase in CEA or CK20 mRNA concentration. In spite of high expression levels in tissues and cell lines, we were not able to differentiate satisfyingly mRNA markers originating from tumor cells and those from illegitimate transcription in hematopoetic cells in blood. We conclude that either copy numbers of analyzed markers in circulating tumor cells are not sufficient for detection or, more probably, peripheral blood is not a suitable compartment for detection of tumor cells in colorectal cancer.

Colon cancer: prevalence, screening, gene expression and mutation, and risk factors and assessment

Colon cancer detection at an early stage and identifying susceptible individuals can result in reduced mortality from this prevalent cancer. Genetic events leading to the development of this cancer involve a multistage progression of adenoma polyps to invasive metastatic carcinomas. Currently, there is no satisfactory screening method that is highly specific, sensitive, or reliable. Dietary patterns associated with the greatest increase in colon cancer risk are the ones that typify a diet rich in fat and calories, and low in vegetable, fruits, and fibers. Genetic susceptibility to environmental carcinogenesis must be factored into the risk assessment for this cancer. Many genes have been shown to be associated with increased expression and mutations in colorectal cancer patients. These genes have been reviewed; it is hoped that by carefully selecting a number of them, a molecular approach that is suitable for arriving at a tumorigenic expression index is developed, which will reliably detect this cancer at an early stage (i.e., before it metastasizes), especially in exfoliated samples (e.g., stool and blood), so that appropriate intervention strategies can be implemented. Illustrated herein is the utility of employing real-time reverse transcriptase polymerase chain reaction (RT-PCR) to quantitatively measure gene expression, and develop an index that is specific for this cancer, which if perfected may result in a reliable and sensitive screening technique for colorectal cancer detection.

Cytokeratin 20 and guanylyl cyclase C mRNA is largely present in lymph node and liver specimens of colorectal cancer patients

The aim of our prospective study was to detect circulating epithelial cells (CEC) indicating the presence of disseminated tumor cells (DTC) in tissues affected by lymphatic and hematogenic colorectal cancer metastasis. DTC were tracked in lymph node, liver or bone marrow samples of 245 colorectal cancer patients using 2 independent RT-PCR assays for cytokeratin 20 (CK20) and guanylylcyclase C (GCC) that demonstrated a sensitivity of 1 colorectal cancer cell in 10(6) nucleated hematopoietic cells. CK20 mRNA was detected in 79% of lymph nodes, 35% of both liver lobes and 11% of bone marrow samples. GCC mRNA was found in 68% of lymph nodes, 60% of both liver lobes and 6% of bone marrow specimens. Both markers were recorded in 63% of lymph nodes, 45% of at least 1 liver lobe and 1% of bone marrow samples. There was no significant difference when comparing lymph node samples tested positive for both markers in patients with (N1/2; 65%) and without (N0; 56%) nodal involvement. The same was true when comparing the percentages of patients with and without clinically overt distant metastasis who were positive for both markers in at least 1 liver lobe (62% vs. 41%) or in bone marrow (4% vs. 0%). A score denoting the cumulative sum of tests indicating presence of CK20 and GCC mRNA in the liver was significantly related with UICC classification (p = 0.039). However, addition of lymph node results to this score decreased the correlation. The high incidence of clinically inconspicuous lymph node and liver samples tested positive for both markers emphasizes the function of these organs as primary filters for epithelial cells possibly shed from colorectal carcinomas. The potential prognostic significance of these findings warrants verification, especially regarding the importance of CEC or DTC resident in the liver of colorectal cancer patients.

Immunohistochemical evaluation for intraoperative rapid pathological assessment of the gastric margin

In patients undergoing surgery for gastric cancer, as the resection area is difficult to define preoperatively, we define the resection area by intraoperative rapid pathological assessment of the resected margin. In some patients, however, the result of postoperative assessment of a permanent section differs from the result obtained intraoperatively. In this study we explored methods of improving the accuracy of intraoperative pathological assessment. Of the patients who underwent surgery for gastric cancer at Takarazuka Municipal Hospital, between April 2000 and July 2001, intraoperative pathological assessment of the resection margin was performed in 34 because it could not be accurately defined preoperatively. The intraoperative assessment consisted of touch smear cytological examination and hematoxylin and eosin (HE) and cytokeratin (CK) histological examination. The time required to perform cytological examination and HE and CK immunohistochemistry by this modified method, which uses an ENVISION Kit/HRP, was approximately 20 minutes for each procedure. Touch smear cytological examination gave false positive results in 3 of 34 patients (8.8%). Of the 14 patients preoperatively diagnosed with signet-ring cell carcinoma, intraoperative HE histological analysis yielded a false negative result in one (7.1%). The results of CK histological assessment of these patients were all consistent with those of postoperative examination of permanent sections. Of the 20 patients preoperatively diagnosed with non-signet-ring cell carcinoma, HE analysis yielded a false negative result in one (5%). The results of CK histological assessment of these patients were all consistent with those of postoperative examination of permanent sections. Our modified CK staining method with the ENVISION Kit/HRP allows intraoperative pathological assessment to be performed accurately and rapidly. This method is more useful than HE immunohistochemistry for the assessment of resected gastric margins.

Intrinsic variability in the detection of micrometastases in lymph nodes for re-staging of colorectal cancer. effect of individual markers and tissue samples

In this study, we investigated whether (a) carcinoembryonic antigen (CEA), cytokeratin-20 (CK-20) and guanylyl cyclase C (GCC) are clinically useful markers for the molecular detection of submicroscopic metastases in colorectal cancer (CRC) and (b) whether overexpression of CEA, CK-20 and GCC can be reliably detected in formalin-fixed, paraffin-embedded tissues as well as frozen lymph nodes. We studied 175 frozen lymph nodes and 158 formalin-fixed, paraffin-embedded lymph nodes from 28 cases of CRC. CEA or CK-20 or GCC-specific polymerase chain reaction (PCR) was carried out on mRNA transcripts extracted from the nodal tissues. Ten out of 11 Dukes' B CRC cases had detectable CEA and CK-20 while 6 out of 11 Dukes' B CRC cases had detectable GCC. In general, the difference of re-staged cases when comparing frozen and paraffin-embedded samples was marked; the only statistically significant correlation between frozen and paraffin tissue was for the CEA marker. Our results indicated a high incidence (>50%) of detecting micrometastases in histologically-negative lymph nodes at the molecular level.

Disseminated single tumor cells as detected by real-time quantitative polymerase chain reaction represent a prognostic factor in patients undergoing surgery for colorectal cancer

OBJECTIVE

To evaluate the clinical relevance of real-time quantitative polymerase chain reaction (qPCR) detection of CEA and CK20 transcripts, as potentially related to tumor cell dissemination, in blood and peritoneal lavage from patients undergoing surgery for colorectal cancer.

SUMMARY BACKGROUND DATA

Dissemination of single colorectal cancer cells in the peritoneal cavity, as well as in tumor drainage and peripheral blood vessels, might play a role in the metastasis process, thus affecting the clinical course. However, this phenomenon needs further elucidation.

METHODS

In a prospective study the authors evaluated the potential of qPCR in the detection of CEA and/or CK20 transcripts in the peritoneal lavage fluid and in the peripheral and mesenteric venous blood of 39 patients undergoing curative resection for colorectal cancer. Peritoneal lavage and peripheral blood was sampled before and after tumor resection; mesenteric venous blood was sampled from the major tumor-draining vein immediately before clamping. After RNA extraction and reverse transcription, qPCR was performed using specific cDNA primers and probes for CEA and CK20. The dichotomous results from the qPCR were used as a predictor along with other covariates in Cox proportional hazard regression models of long-term outcome (disease-free survival and overall survival).

RESULTS

Of 39 patients, 11 were positive. The median follow-up at analysis was 31 months for all patients. The dichotomous qPCR covariate was significant, with P =.001 and.0035 for disease-free survival and overall survival, respectively, in the proportional hazard regression models with only qPCR. In seven patients, disseminated colorectal cancer cells were found in the peritoneal lavage fluid but not in blood specimens; five of these patients (71%) had recurrence.

CONCLUSIONS

These data suggest that detection of mRNA coding for CEA and/or CK20 using qPCR has potential clinical utility as a prognostic marker and should be evaluated in larger clinical studies. Identification of patients at high risk for metastatic disease after curative resection of colorectal cancer might be improved by analyzing peritoneal lavage specimens in addition to blood samples. This is based on the observation that in more than half of qPCR-positive patients, disseminated colorectal cancer cells were detected in peritoneal lavage specimens but not in blood samples, and that 71% of them had recurrence.

Detection of hematogenic and lymphogenic tumor cell dissemination in patients with medullary thyroid carcinoma by cytokeratin 20 and preprogastrin-releasing peptide RT-PCR

Despite an extensive surgical approach only 50% of the patients with medullary thyroid carcinoma (MTC) are biochemically cured. The failure to cure a larger number of patients is a result of the early dissemination of MTC. The present study evaluates two RT-PCR based assays for the detection of disseminated tumor cells in blood, bone marrow and lymph node samples of patients with MTC. Frozen tissue and blood samples of 19 patients with MTC and 61 cervical lymph nodes of these patients were obtained intraoperatively during thyroidectomy and lymphadenectomy. Preoperative bone marrow samples were obtained from 8 patients with MTC. An expression of CK20 and preproGRP was found in all MTC tissue samples. Using CK20-PCR, disseminated MTC cells were detected in 67% of the cervical lymph nodes of patients with MTC, compared to 72% involved lymph nodes, detected by preproGRP-PCR. In 16 of 61 nodes (26%) each PCR-system detected disseminated tumor cells in histologically tumor-free lymph nodes. Disseminated tumor cells were detected with CK20-PCR and preproGRP in 5 of 18 (28%) preoperative blood samples, each. The detection of a hematogenic tumor cell dissemination by preproGRP correlated significantly with the tumor stages (p = 0.019). Circulating MTC cells were found in 3 of 8 bone marrow samples with CK20-PCR, compared to 1 of 8 samples with preproGRP-PCR. Both PCR assays are highly sensitive to detect disseminated MTC cells in blood, bone marrow and lymph node samples. Our results of disseminated MTC cells in 26% of histologically tumor-free cervical lymph nodes and in 28% of the blood samples of patients with MTC might therefore explain the low biochemical cure rates.

Quantification of cytokeratin 20, carcinoembryonic antigen and guanylyl cyclase C mRNA levels in lymph nodes may not predict treatment failure in colorectal cancer patients

Conventional histopathologic staging of primary colorectal cancers does not allow accurate prognostic stratification within a given tumour stage. Therefore, PCR-based assays are increasingly used to try to predict more accurately the likelihood of disease progression for the individual patient. Real-time reverse transcription PCR (RT-PCR) assays were used to detect and quantitate cytokeratin 20 (ck20), carcinoembryonic antigen (CEA) and guanylyl cyclase C (GCC) mRNA in 149 lymph nodes (LN) from 17 patients with benign disease and 302 LN from 42 patients with colorectal cancer who had curative (R0) resections. None of the markers were specific, with ck20, CEA and GCC mRNA detected in 47%, 89% and 13% of 149 LN, respectively, from patients with benign disease. The sensitivity of all 3 markers was very high, with mRNA detected in 93%, 100% and 97% of 30 histologically involved LN, respectively. There was significant overlap in the mRNA levels of all 3 markers between histologically involved and uninvolved LN. There was no association between mRNA levels and distant recurrence (median follow-up: 3.94 years, range 3.35-5.12). We conclude that the use of molecular techniques to detect occult disease in LN may suffer from the same limitations as conventional methods. Instead, accurate prognostic stratification requires careful assessment of the likely metastatic potential of the primary cancer.

Disseminated single tumor cells as detected by real-time quantitative polymerase chain reaction represent a prognostic factor in patients undergoing surgery for colorectal cancer

OBJECTIVE

To evaluate the clinical relevance of real-time quantitative polymerase chain reaction (qPCR) detection of CEA and CK20 transcripts, as potentially related to tumor cell dissemination, in blood and peritoneal lavage from patients undergoing surgery for colorectal cancer.

SUMMARY BACKGROUND DATA

Dissemination of single colorectal cancer cells in the peritoneal cavity, as well as in tumor drainage and peripheral blood vessels, might play a role in the metastasis process, thus affecting the clinical course. However, this phenomenon needs further elucidation.

METHODS

In a prospective study the authors evaluated the potential of qPCR in the detection of CEA and/or CK20 transcripts in the peritoneal lavage fluid and in the peripheral and mesenteric venous blood of 39 patients undergoing curative resection for colorectal cancer. Peritoneal lavage and peripheral blood was sampled before and after tumor resection; mesenteric venous blood was sampled from the major tumor-draining vein immediately before clamping. After RNA extraction and reverse transcription, qPCR was performed using specific cDNA primers and probes for CEA and CK20. The dichotomous results from the qPCR were used as a predictor along with other covariates in Cox proportional hazard regression models of long-term outcome (disease-free survival and overall survival).

RESULTS

Of 39 patients, 11 were positive. The median follow-up at analysis was 31 months for all patients. The dichotomous qPCR covariate was significant, with P =.001 and.0035 for disease-free survival and overall survival, respectively, in the proportional hazard regression models with only qPCR. In seven patients, disseminated colorectal cancer cells were found in the peritoneal lavage fluid but not in blood specimens; five of these patients (71%) had recurrence.

CONCLUSIONS

These data suggest that detection of mRNA coding for CEA and/or CK20 using qPCR has potential clinical utility as a prognostic marker and should be evaluated in larger clinical studies. Identification of patients at high risk for metastatic disease after curative resection of colorectal cancer might be improved by analyzing peritoneal lavage specimens in addition to blood samples. This is based on the observation that in more than half of qPCR-positive patients, disseminated colorectal cancer cells were detected in peritoneal lavage specimens but not in blood samples, and that 71% of them had recurrence.

Comparative detection of lymph node micrometastases of stage II colorectal cancer by reverse transcriptase polymerase chain reaction and immunohistochemistry

PURPOSE

Inconsistent conclusions have been drawn about the clinical significance of micrometastases in lymph nodes (LNs) of node-negative colorectal cancer (CRC) patients. We performed a comparative study of detection of micrometastases using immunohistochemistry (IHC) by anti-cytokeratin antibody and carcinoembryonic antigen (CEA)-specific reverse-transcriptase polymerase chain reaction (RT-PCR) in the same patients, in an attempt to move closer to their clinical application.

PATIENTS AND METHODS

Sixty-four CRC patients, with RNA of good quality available from paraffin-embedded LN specimens, were selected from 84 stage II patients who underwent curative surgery between 1988 and 1996. We investigated associations between the presence of micrometastases by each method and prognosis.

RESULTS

Micrometastases were detected in 19 (29.6%) of 64 patients by RT-PCR and in 35 (54.7%) of 64 patients by IHC. By RT-PCR analysis, patients exhibiting a positive band for CEA mRNA had a significantly worse prognosis than those who were RT-PCR-negative, with respect to both disease-free and overall survival (P =.027 and.015, respectively). By IHC analysis, the presence of micrometastasis did not predict patient outcome in terms of either disease-free or overall survival. Infiltrating pattern of tumor growth characteristic was significantly associated with shorter disease-free survival among various clinical or pathologic factors. By multivariate Cox regression analysis, micrometastasis detected by RT-PCR and the Crohn's-like lymphoid reaction were both independent prognostic factors.

CONCLUSION

Micrometastases detected by RT-PCR, but not IHC, may be of clinical value in identifying patients who may be at high risk for recurrence of CRC and who are therefore likely to benefit from systemic adjuvant therapy.

Validation of sentinel node mapping in patients with colon cancer

BACKGROUND

Sentinel lymph node (SLN) mapping techniques have been validated in breast cancer and melanoma. This study summarizes our experience with SLN mapping for colon cancer.

METHODS

Fifty-five patients with colon cancer underwent intraoperative SLN mapping. One mL of 1% isosulfan blue was injected subserosally around the tumor. The first nodes highlighted with blue were identified as the SLNs. SLNs underwent multiple sectioning and immunohistochemical staining for cytokeratin. The overall learning curve was calculated.

RESULTS

Lymphatic mapping adequately identified at least 1 SLN in 45 patients (82%). SLNs adequately predicted regional status in 44 of 45 (98%) cases. In 9 of 45 cases (20%), the SLNs were the only sites of metastases. Among the 14 cases that were SLN positive, 6 of 55 patients (11%) were positive only by immunohistochemistry. Of the 31 cases with negative SLNs, 1 case had a 3.5-mm pericolonic tumor-replaced non-SLN (3% false-negative rate). The overall learning curve stabilized after five cases.

CONCLUSIONS

Intraoperative SLN mapping is a feasible technique, with a quick learning curve, and had a reasonable SLN identification rate. Negative SLNs accurately predict the status of non-SLNs 97% of the time. Eleven percent of patients were upstaged by demonstration of micrometastases and may benefit from adjuvant chemotherapy.

Lymph node micrometastasis and lymphatic mapping determined by reverse transcriptase-polymerase chain reaction in pN0 gastric carcinoma

BACKGROUND

The purposes of this study were to examine lymph node micrometastasis (LMM) by reverse transcriptase-polymerase chain reaction (RT-PCR) method, and clarify the initial nodes involved by metastatic disease according to tumor location.

METHODS

We examined 312 lymph nodes obtained from 50 patients with node-negative gastric carcinoma. RT-PCR and immunohistochemistry were performed. The clinical characteristics of LMM were investigated, and the map of LMM was made according to tumor location.

RESULTS

The number of patients and LMM detected by RT-PCR was 14 and 17 and by immunohistochemistry was 7 and 8, respectively. RT-PCR was a more sensitive method than immunohistochemistry. LMM by RT-PCR correlated with depth of tumor invasion and lymphatic invasion. Regarding pT1 tumor, 9 patients with LMM had tumors that were of the macroscopically depressed type and 2 cm or more in diameter. According to the lymphatic map, right pericardial lymph nodes and lymph nodes along the lesser curvature were the initial nodes involved in the upper third of the stomach. Right pericardial lymph nodes, lymph nodes along the lesser curvature, and infrapyloric nodes were more important initial metastatic sites in the middle third of the stomach, and lymph nodes along the lesser curvature and infrapyloric nodes in the lower third.

CONCLUSIONS

We demonstrated the relationship between LMM and clinicopathologic factors, especially in pT1 tumor. The mapping of LMM may prove useful for selecting the optimal treatment.

Prognostic significance of cytokeratin-20 reverse transcriptase polymerase chain reaction in lymph nodes of node-negative colorectal cancer patients

PURPOSE

Approximately 20% to 30% of patients with curatively resected, node-negative (pN0) colorectal cancer die of tumor recurrence, which can be caused by minimal residual disease. To identify patients with an increased risk of tumor recurrence and evaluate the prognostic value of cytokeratin-20 (CK-20), we detected CK-20-positive cells in histopathologically tumor-free lymph nodes (pN0) of patients with colorectal cancer.

PATIENTS AND METHODS

Two peritumoral lymph nodes each from 85 patients with completely resected (R0) colorectal cancer without lymph node metastases (pN0) by routine examination were analyzed using a CK-20-specific reverse transcriptase polymerase chain reaction (RT-PCR) and compared with CK-20-specific immunohistochemistry (IHC). The results were correlated with histopathologic findings and with survival.

RESULTS

CK-20 RT-PCR was positive in 44 patients (52%) and detected 83% of cancer-related death. Positive RT-PCR was significantly correlated with poorer overall survival (P <.009). Comparing RT-PCR with IHC, 13 patients with positive RT-PCR were identified, where the CK-20 expression was caused by tumor cell contamination located exclusively outside the lymph node capsule and had no prognostic impact. Defining these 13 patients as RT-PCR negative improved specificity of the RT-PCR assay from 57% to 75%. The 5-year overall survival of the 31 RT-PCR-positive patients was 71%, compared with 96% in the 54 negative patients (P <.001). Multivariate analysis showed expression of CK-20 mRNA to be an independent prognostic factor with a relative risk of cancer-related death of 6.1.

CONCLUSION

CK-20 RT-PCR in peritumoral histopathologic tumor-free (pN0) lymph nodes of colorectal cancer is an independent prognostic factor for overall survival. Additional CK-20 IHC improves the specificity and prognostic value of RT-PCR for cancer-related death.

Molecular pathology of tumor metastasis. II. Molecular staging and differential diagnosis

Molecular Pathology of Tumor Metastasis With the development of non-invasive methods, diagnosis of metastasis from various solid malignancies has become a routine task for diagnostic pathology. However, the differential diagnosis between primary and metastatic cancers and the precise identification of various metastatic cancer types requires the coordinated use of various morphological (light- and electron microscopic-), immunological and molecular techniques. The detection of the lymphatic spread of the primary tumor may now based on the sentinel lymph node technology while the identification of the hematogenous progression may be based on the analysis of the peripheral blood and the bone marrow. More and more frequently these techniques employ highly sensitive immunological and molecular techniques. Accordingly, clinical staging is now confronted with the results of molecular staging, where the only techniques which are able to detect cancer cells are immunocytochemistry or nucleic acid-based methodology. Although several clinical studies have provided evidences for the impact of the immunocytochemistry-based identification of micrometastases on the survival of patients with various type of cancers, none of these methods have become part of standard diagnostic protocols. Although more sensitive molecular techniques are being introduced to identify micrometastasis, their clinical significance is yet unknown. Multicentric clinical trials are now warranted to establish the clinical impact of molecular staging in various cancer types. Without the integration of these methods into the prognostic/predictive pathological protocols it is difficult to envision significant improvement in the results of cancer therapy.

Construction and selection of the natural immune Fab antibody phage display library from patients with colorectal cancer

AIM: To construct the natural immune Fab antibody phage display libraries of colorectal cancer and to select antibodies related with colorectal cancer.

METHODS: Extract total RNA from tissue of local cancer metastasis lymph nodes of patients with colorectal cancer. RT-PCR was used to amplify the heavy chain Fd and light chain κ and the amplification products were inserted successively into the vector pComb3 to construct the human libraries of Fab antibodies. They were then panned by phage display technology. By means of Dot immunoblotting and ELISA, the libraries were identified and the Fab phage antibodies binding with antigens of colorectal cancer were selected.

RESULTS: The amplified fragments of Fd and κ gained by RT-PCR were about 650 bp. Fd and κ PCR products were subsequently inserted into the vector pComb3, resulting in a recombination rate of 40% and the volume of Fab phage display library reached 1.48 × 10⁶. The libraries were enriched about 120-fold by 3 cycles of adsorption-elution-multiplication (panning). Dot immunoblotting showed Fab expressions on the phage libraries and ELISA showed 5 clones of Fab phage anti bodies which had binding activities with antigens of colorectal cancer.

CONCLUSION: The natural immune Fab antibody phage display libraries of colorectal cancer were constructed. They could be used to select the relative antibodies of colorectal cancer.

Genetic detection of lymph node micrometastases in patients with gastric carcinoma by multiple-marker reverse transcriptase-polymerase chain reaction assay

BACKGROUND

Some patients with gastric carcinoma experience local disease recurrence despite undergoing curative resection of the tumor and regional lymph nodes (LNs), suggesting the presence of occult micrometastases. To evaluate the presence of gastric carcinoma micrometastasis in patients with otherwise histologically negative LNs, the authors established and tested a multiple-marker reverse transcriptase-polymerase chain reaction (RT-PCR) assay.

METHODS

The authors assessed 435 LNs from 28 patients with gastric carcinoma who underwent gastrectomy with lymphadenectomy using the multiple-marker RT-PCR assay in addition to histologic examination. Carcinoembryonic antigen (CEA), cytokeratin-20 (CK-20), and MAGE-3 gene markers were used in this assay. LNs were scored positive for metastasis if at least one marker was positive. The presence of LN micrometastases also was verified by immunohistochemistry in histologically negative and RT-PCR positive LNs.

RESULTS

Sixty-nine of 435 LNs (16%) were positive for CEA (12%), CK-20 (10%), or MAGE-3 (5%). None of 16 control LNs obtained from disease free patients was positive by RT-PCR assay. Of 414 histologically negative LNs, 50 LNs (12%) were scored as positive for metastasis by the assay. Of 26 patients who underwent curative resection, the disease stage was upgraded in 10 patients by genetic diagnosis (from Stage IA to Stage IB in 5 patients, from Stage IB to Stage IIIA in 2 patients, from Stage IB to Stage IV in 1 patient, from Stage IB to Stage II in 1 patient, and from Stage II to Stage IIIB in 1 patient). In the latter 10 patients, immunohistochemistry identified LN micrometastases in 4 patients. Two patients with micrometastasis by genetic diagnosis had recurrent disease within 1 year.

CONCLUSIONS

The current results indicate that the multiple-marker RT-PCR assay is a useful tool for the detection of micrometastases in regional LNs in patients with gastric carcinoma and may improve the staging system of gastric carcinoma for these patients.

Genetic detection of lymph node micrometastases in patients with gastric carcinoma by multiple-marker reverse transcriptase-polymerase chain reaction assay

BACKGROUND

Some patients with gastric carcinoma experience local disease recurrence despite undergoing curative resection of the tumor and regional lymph nodes (LNs), suggesting the presence of occult micrometastases. To evaluate the presence of gastric carcinoma micrometastasis in patients with otherwise histologically negative LNs, the authors established and tested a multiple-marker reverse transcriptase-polymerase chain reaction (RT-PCR) assay.

METHODS

The authors assessed 435 LNs from 28 patients with gastric carcinoma who underwent gastrectomy with lymphadenectomy using the multiple-marker RT-PCR assay in addition to histologic examination. Carcinoembryonic antigen (CEA), cytokeratin-20 (CK-20), and MAGE-3 gene markers were used in this assay. LNs were scored positive for metastasis if at least one marker was positive. The presence of LN micrometastases also was verified by immunohistochemistry in histologically negative and RT-PCR positive LNs.

RESULTS

Sixty-nine of 435 LNs (16%) were positive for CEA (12%), CK-20 (10%), or MAGE-3 (5%). None of 16 control LNs obtained from disease free patients was positive by RT-PCR assay. Of 414 histologically negative LNs, 50 LNs (12%) were scored as positive for metastasis by the assay. Of 26 patients who underwent curative resection, the disease stage was upgraded in 10 patients by genetic diagnosis (from Stage IA to Stage IB in 5 patients, from Stage IB to Stage IIIA in 2 patients, from Stage IB to Stage IV in 1 patient, from Stage IB to Stage II in 1 patient, and from Stage II to Stage IIIB in 1 patient). In the latter 10 patients, immunohistochemistry identified LN micrometastases in 4 patients. Two patients with micrometastasis by genetic diagnosis had recurrent disease within 1 year.

CONCLUSIONS

The current results indicate that the multiple-marker RT-PCR assay is a useful tool for the detection of micrometastases in regional LNs in patients with gastric carcinoma and may improve the staging system of gastric carcinoma for these patients.

Detection and clinical significance of occult tumour cells in colorectal cancer

BACKGROUND

A variety of techniques have been employed for the detection of occult tumour cells in the blood, bone marrow and lymph nodes of patients with colorectal cancer. This review examines the methods used, results obtained and the clinical significance of studies in this field.

METHODS

A Medline literature search was performed using the terms colorectal cancer, minimal residual disease, micrometastasis, polymerase chain reaction, reverse transcriptase polymerase chain reaction and immunocytochemistry; further references were obtained from key articles.

RESULTS

Immunocytochemical examination of bone marrow is the benchmark for detecting clinically significant occult disease. Larger standardized studies are required to confirm the prognostic significance of molecular assays for the detection of tumour cells in blood and bone marrow. The prognostic significance of lymph node tumour cells detected by either immunohistochemical or molecular methods awaits further affirmation.

CONCLUSION

Standardization of terminology and techniques used, combined with large prospective clinical studies, is required if detection of occult residual disease is to become a prognostic marker for recurrence in colorectal cancer.

Intraoperative sentinel lymph node mapping in patients with colon cancer

BACKGROUND

The sentinel lymph node (SLN) mapping technique has been used in breast cancer and melanoma, and was recently described for colon cancer.

METHODS

Thirty-five patients with colon cancer underwent intraoperative SLN mapping. One milliliter of 1% isosulfan blue was injected subserosally around the tumor. The first nodal area that was highlighted with blue was identified as the SLN. All lymph nodes underwent examination with hematoxylin and eosin (H&E) stain. SLNs underwent additional sectioning and were stained with CAM 5.2.

RESULTS

Lymphatic mapping adequately identified the SLN in 25 patients (71%). In the 15 cases where the SLNs were negative for metastases, all other non-SLNs were also negative (0% false negative rate). The SLN was the only site of metastases in 6 (17%) of 35 patients. CAM 5.2 staining provided the only evidence of micrometastases in 4 (11%) of 35 patients.

CONCLUSIONS

Intraoperative SLN mapping is a feasible technique with a reasonable SLN identification rate (71%). The absence of metastases in the SLNs accurately predicts the status of the non-SLNs. Tumors in 11% of patients were upstaged by the demonstration of micrometastatic involvement, and these patients may benefit from further adjuvant chemotherapy.

Orthotopic transplantation model of human gastrointestinal cancer and detection of micrometastases

AIM: To establish a relevant animal model of human gastrointestinal cancer, which can be used for repetitive investigations, so as to improve our understanding and management of carcinogenesis and cancer metastasis.

METHODS: Intact tissues of human colorectal and pancreatic cancers were transplanted in nude mice. The biological characteristics of the original and the corresponding transplanted tumors were investigated by HE staining, PAS staining and immunostaining. The metastases in the livers and lungs of nude mice were investigated by immunostaining with biotinylated mab KL-1 and by RT-PCR using CK20 specific primers.

RESULTS: There were totally 9 of 16 surgical specimens growing in nude mice subcutaneously and/or orthotopically (4 of 6 colorectal and 5 of 10 pancreatic cancer). Tumor cell content of the specimens and freezing of tissue specimens are important factors influencing the growth of transplanted tumor. In the group of fresh tumor tissues with greater than 50% tumor cell content, the success rate of the transplantation was 100% (3 cases of pancreatic cancer and 3 cases of colorectal cancer). The orthotopically transplanted tumors resemble the original tumor morphologically and biologically, including TAA expression such as CEA by immunohistochemistry, and CEA level in the serum of mice. Ki-67 labeling index and the expression of TAA especially K-ras, 17-1A and RA-96, are associated with the potential of tumor growth in nude mice. Micrometastases in the lungs and livers of tumor bearing mice can be detected by immunostaining with biotinylated mab KL-1 and CK20-specific RT-PCR.

CONCLUSION: An orthotopic transplantation model for human colon and pancreatic cancer in nude mice has been set up. We have also established sensitive detection methods with CK-immunohistochemistry and CK20-RT-PCR to study xenotransplanted human cancer and its metastatic cancer cells in the liver and lung of nude mice. This study may be helpful in understanding the mechanism of cancer metastasis and in developing new diagnostic methods and therapeutic strategies for metastases including micrometastases.

Skip metastases in colon cancer: assessment by lymph node mapping using molecular detection

BACKGROUND

Colon cancer has been assumed to spread sequentially through the regional lymphatic bed, with skip metastases occurring in only 1% to 3% of cases. Molecular techniques allow the detection of occult metastases, but to date have not been applied to assess the pattern of regional lymphatic spread of colon cancer.

METHODS

Fifty-five tumors from 54 patients with colonic adenocarcinoma were studied. Lymph node mapping was performed on fresh colonic specimens recording the position of each node on an anatomical diagram. Half of each lymph node was submitted for routine histology examination and half assayed for keratin 20 gene expression by reverse transcription-polymerase chain reaction. Logistic regression was used to analyze the distribution of histologic and occult metastases.

RESULTS

A total of 1084 lymph nodes were dissected (median, 19 nodes; range, 4-52). Sixty-four lymph nodes from 20 tumors had histologically evident metastases and 76 lymph nodes from 13 tumors had occult metastases. There was no difference in the distribution of either histologic or occult metastases among paracolic, intermediate, and apical node groups. Ten patients had evidence of anatomical skip lesions after lymph node mapping and molecular analysis, only 1 of which was histologically detectable.

CONCLUSIONS

This study demonstrates a higher incidence of skip metastases in colon cancer assessed by molecular techniques than has previously been reported, challenging the concept of sequential development of early lymph node metastases.

Implications of occult metastatic cells for systemic cancer treatment in patients with breast or gastrointestinal cancer

The early and clinically occult spread of viable tumour cells to the organism is becoming acknowledged as a hallmark in cancer progression, since abundant clinical and experimental data suggest that these cells are precursors of subsequent distant relapse. Using monoclonal antibodies against epithelial cytokeratins or tumour-associated cell membrane glycoproteins, individual carcinoma cells can be detected in cytological bone marrow preparations at frequencies of 10(-5) to 10(-6). Prospective clinical studies have shown that the presence of such immunostained cells in bone marrow is prognostically relevant with regard to relapse-free and overall survival, even in malignancies that do not preferentially metastasise to bone. As current treatment strategies have resulted in a substantial improvement of cancer mortality rates, it is noteworthy to consider the intriguing options of immunocytochemical screening of bone marrow aspirates for occult metastatic cells. Besides improved tumour staging, such screening offers opportunities for guiding patient stratification for adjuvant therapy trials, monitoring response to adjuvant therapies (which, at present, can only be assessed retrospectively after an extended period of clinical follow-up), and specifically targeting tumour-biological therapies against disseminated tumour cells. The present review summarises the current data on the clinical significance of occult metastatic cancer cells in bone marrow.

Clinical significance of K-Ras mutations in intraoperative tumor drainage blood from patients with colorectal carcinoma

BACKGROUND

Recurrent and metastatic carcinoma of the colorectum remains a major problem. This may be ascribed to the presence of micrometastasis at diagnosis. The purpose of this study was to analyze prospectively the clinical value of detecting K-ras mutations in the perioperative circulating blood from patients with colorectal carcinoma.

METHODS

Twenty-four patients whose tumor carried mutations in codon 12 of the K-ras gene were studied for the presence of cancer cells in perioperative blood samples, in particular, tumor drainage samples. A detection assay using CD45 immunomagnetic separation plus nested mutant allele specific amplification (MASA) was performed.

RESULTS

K-ras mutations in CD45 negative cells in tumor drainage blood were detected in 7 (29.2%) of 24 patients. There was no significant relationship between the presence of a K-ras mutation and clinicopathological features. Four (57.1%) of the seven patients with a positive K-ras mutation in drainage blood had early recurrent disease. Of the 17 patients with no K-ras mutation, none developed metastatic disease. The recurrence rate of the K-ras mutation positive group was higher than that of the K-ras mutation negative group (P < .01). There was a significant difference, regarding prognosis, between K-ras mutation positive and negative groups (P < .01).

CONCLUSIONS

This preliminary study demonstrates that the detection of circulating cancer cells in the tumor drainage blood by our new assay system may provide a predictor of recurrence and metastasis of colorectal cancer.

Minimal residual disease in gastrointestinal cancer

Tumor progression after curative resection of gastrointestinal carcinomas is probably caused by pre- or intraoperative tumor cell dissemination. Disseminated tumor cells are generally detected by immunohistochemistry- or PCR-based molecular-biology methods. A consensus on which is the most adequate detection method has not yet been found, which makes the comparison of data difficult. The prognostic relevance of disseminated cells has been shown, at least in part, for esophageal, gastric, pancreatic, and colonic cancer. The data regarding hepatocellular cancer is conflicting. This article gives a critical review of tumor cell detection in gastrointestinal cancer.