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

TUMOR MARKERS EXPRESSION LEVELS IN GASTRIC CANCER PATIENT'S PERIPHERAL BLOOD BY RT-PCR ASSESSMENT

BACKGROUND

Hematological recurrence is the second most frequent cause of failure in the treatment of gastric cancer. The detection of circulating tumor markers in peripheral blood by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) method may be a useful tool to predict recurrence and determine the patient's prognosis. However, no consensus has been reached regarding the association between the tumor markers level in peripheral blood and its impact on patient survival.

AIMS

To evaluate the expression of the circulating tumor markers CK20 and MUC1 in peripheral blood samples from patients with gastric cancer by qRT-PCR, and to verify the association of their expression levels with clinicopathological characteristics and survival.

METHODS

A total of 31 patients with gastric adenocarcinoma were prospectively included in this study. CK20 and MUC1 expression levels were analyzed from peripheral blood by the qRT-PCR technique.

RESULTS

There was no statistically significant (p>0.05) association between CK20 expression levels and clinical, pathological, and surgical features. Higher MUC1 expression levels were associated with female patients (p=0.01). There was a correlation between both gene levels (R=0.81, p<0.001), and CK20 level and tumor size (R=0.39, p=0.034).

CONCLUSIONS

CK20 and MUC1 expression levels could be assessed by qRT-PCR from total peripheral blood samples of patients with gastric cancer. CK20 levels were correlated to MUC1 levels as well as to tumor size. There was no difference in disease-free survival and overall survival regarding both genetic markers expression in this series.

A genomic-clinicopathologic Nomogram for the preoperative prediction of lymph node metastasis in gastric cancer

BACKGROUND

Preoperative evaluation of lymph node (LN) state is of pivotal significance for informing therapeutic decisions in gastric cancer (GC) patients. However, there are no non-invasive methods that can be used to preoperatively identify such status. We aimed at developing a genomic biosignature based model to predict the possibility of LN metastasis in GC patients.

METHODS

We used the RNA profile retrieving strategy and performed RNA expression profiling in a large GC cohort (GSE62254, n = 300) from Gene Expression Ominus (GEO). In the exploratory stage, 300 GC patients from GSE62254 were involved and the differentially expressed RNAs (DERs) for LN-status were determined using the R software. GC samples in GSE62254 were randomly allocated into a learning set (n = 210) and a verification set (n = 90). By using the Least absolute shrinkage and selection operator (LASSO) regression approach, a set of 23-RNA signatures were established and the signature based nomogram was subsequently built for distinguishing LN condition. The diagnostic efficiency, as well as the clinical performance of this model were assessed using the decision curve analysis (DCA). Metascape was used for bioinformatic analysis of the DERs.

RESULTS

Based on the genomic signature, we established a nomogram that robustly distinguished LN status in the learning (AUC = 0.916, 95% CI 0.833-0.999) and verification sets (AUC = 0.775, 95% CI 0.647-0.903). DCA demonstrated the clinical value of this nomogram. Functional enrichment analysis of the DERs was performed using bioinformatics methods which revealed that these DERs were involved in several lymphangiogenesis-correlated cascades.

CONCLUSIONS

In this study, we present a genomic signature based nomogram that integrates the 23-RNA biosignature based scores and Lauren classification. This model can be utilized to estimate the probability of LN metastasis with good performance in GC. The functional analysis of the DERs reveals the prospective biogenesis of LN metastasis in GC.

Clinical significance of circulating tumor cells in gastric cancer patients

Circulating tumor cells (CTCs) are rare cancer cells released from tumors into the blood stream that are thought to have a key role in cancer metastasis. Investigation of CTCs is an exciting area of research but remains in its infancy, and the presence of CTCs has been associated with worse prognosis in several major cancer types. Gastric cancer (GC) is a highly lethal malignancy and a serious public health concern in East Asia especially in China. There is an urgent need for identifying new, better prognostic markers to enhance diagnosis and prognosis, facilitate drug development, and to improve the treatment of gastric cancer patients. There are considerable interests in gastric CTCs given their potential use as gastric cancer biomarkers. This review highlights recent advances in studies of gastric CTCs, including the isolation and biological molecular characteristics of gastric CTCs, and their clinical significance.

[Micrometastasis in Gastric Cancer]

Although the incidence and mortality rate of gastric cancer have been steadily declining, gastric cancer is still the fourth most common cancer in the world and more than 50% of cases occur in Eastern Asia. In Korea, gastric cancer is the second most common cancer and third cause of cancer related death. The standard surgical procedure for resectable advanced gastric cancer is D2 lymphadenectomy with radical gastrectomy. Even though R0 resection was completed, recurrence is relatively common, and contributes to the limited survival of the patients in gastric cancer. As a clinically relevant factor for detection of the recurrence, the presence of isolating tumor cells has been introduced and it is so called as 'micrometastasis'. Numerous immunohistochemistry and molecular studies have shown that micrometastasis can be demonstrated not only in lymph nodes but also in such body compartments as the bone marrow, peritoneal cavity and blood. Herein, we review the current knowledge and evidence of the prognostic significance of micrometastasis in peritoneal, lymph node, bone marrow. Also, we discuss the current state of research on the circulating tumor cell in peripheral blood.

New evidence guiding extent of lymphadenectomy for esophagogastric junction tumor: Application of Ber-Ep4 Joint with CD44v6 staining on the detection of lower mediastinal lymph node micrometastasis and survival analysis

For Siewert type II adenocarcinoma of the esophagogastric junction (AEJ), the optimal surgical approach and extent of lymph nodes dissection remain controversial. Immunohistochemistry (IHC) has been reported to be available for identifying lymph node micrometastasis (LNMM) in patients with AEJ. This was a prospective case series of patients who underwent R0 resection and lower mediastinal lymphadenectomy from January 2010 to June 2015 in Fujian Medical University Union Hospital for Siewert type II AEJ. The outcomes were analyzed retrospectively. A total of 1325 lymph nodes were collected from 49 patients, grouped into 3 groups: lower mediastinal, paracardial, and abdominal. The former 2 groups were examined by monoclonal antibodies against Ber-Ep4 and CD44v6. The incidence of LNMM in mediastinal group was 37% (18/49) for Ber-Ep4 and 33% (16/49) for CD44v6. While in routine histological diagnosis, the number of patients with the positive lymph nodes was 7 (14%). When combining IHC with histopathology (HE) staining, the incidence of positive mediastinal lymph nodes was increased to 24%, with a total number of 37 lymph nodes from 28 patients (57%). Micrometastases indicated by Ber-Ep4 and CD44v6 were associated with the depth of tumor invasion (P = 0.020 and 0.037, respectively), histopathological nodal status (P = 0.024 and 0.01, respectively), and Lauren classification (P = 0.038 and, respectively). Expression of CD44v6 and Ber-Ep4 was positively correlated (r = 0.643, P < 0.001). The 3- and 5-year survival rates for all patients were 66% and 50%, respectively. The patients with LNMM had a lower 3-year survival rate of 51%, compared to 80% from no LNMM group; 5-year survival rate was also lower in LNMM group, which is 29% versus 68% (P = 0.006) in the no LNMM group. Patients with positive Ber-Ep4 cells had a lower survival, but not statistically significant (P = 0.058). CD44v6-positive group had a significantly reduced survival (P < 0.001). In patients group with negative lower mediastinal lymph nodes, patients without LNMM obtained a significant survival benefit (P = 0.021). Our study demonstrated that routine test for LNMM is necessary for patients with negative lymph nodes. As a positive prognostic factor, thorough lower mediastinal lymphadenectomy in an invasive approach should be considered when necessary. Ber-Ep4 and CD44v6 were shown to be great markers for detecting LNMM.

DETECTION OF OCCULT LYMPH NODE TUMOR CELLS IN NODE-NEGATIVE GASTRIC CANCER PATIENTS

BACKGROUND

The presence of lymph nodes metastasis is one of the most important prognostic indicators in gastric cancer. The micrometastases have been studied as prognostic factor in gastric cancer, which are related to decrease overall survival and increased risk of recurrence. However, their identification is limited by conventional methodology, since they can be overlooked after routine staining.

AIM

To investigate the presence of occult tumor cells using cytokeratin (CK) AE1/AE3 immunostaining in gastric cancer patients histologically lymph node negative (pN0) by H&E.

METHODS

Forty patients (T1-T4N0) submitted to a potentially curative gastrectomy with D2 lymphadenectomy were evaluated. The results for metastases, micrometastases and isolated tumor cells were also associated to clinicopathological characteristics and their impact on stage grouping. Tumor deposits within lymph nodes were defined according to the tumor-node-metastases guidelines (7th TNM).

RESULTS

A total of 1439 lymph nodes were obtained (~36 per patient). Tumor cells were detected by immunohistochemistry in 24 lymph nodes from 12 patients (30%). Neoplasic cells were detected as a single or cluster tumor cells. Tumor (p=0.002), venous (p=0.016), lymphatic (p=0.006) and perineural invasions (p=0.04), as well as peritumoral lymphocytic response (p=0.012) were correlated to CK-positive immunostaining tumor cells in originally negative lymph nodes by H&E. The histologic stage of two patients was upstaged from stage IB to stage IIA. Four of the 28 CK-negative patients (14.3%) and three among 12 CK-positive patients (25%) had disease recurrence (p=0.65).

CONCLUSION

The CK-immunostaining is an effective method for detecting occult tumor cells in lymph nodes and may be recommended to precisely determine tumor stage. It may be useful as supplement to H&E routine to provide better pathological staging.

Comparison of the Diagnostic Value Between Real-Time Reverse Transcription-Polymerase Chain Reaction Assay and Histopathologic Examination in Sentinel Lymph Nodes for Patients With Gastric Carcinoma

OBJECTIVES

Sentinel lymph node (SLN)-based diagnosis in gastric cancers has shown varied sensitivities and false-negative rates in several studies. Application of the reverse transcription-polymerase chain reaction (RT-PCR) in SLN diagnosis has recently been proposed.

METHODS

A total of 155 SLNs from 65 patients with cT1-2, N0 gastric cancer were examined. The histopathologic results were compared with results obtained by real-time RT-PCR for detecting molecular RNA (mRNA) of cytokeratin (CK)19, carcinoembryonic antigen (CEA), and CK20.

RESULTS

The sensitivity and specificity of the multiple marker RT-PCR assay standardized against the results of the postoperative histological examination were 0.778 (95% confidence interval [CI], 0.577-0.914) and 0.781 (95% CI, 0.700-0.850), respectively. In comparison, the sensitivity and specificity of intraoperative diagnosis were 0.819 (95% CI, 0.619-0.937) and 1.000 (95% CI, 0.972-1.000), respectively. The positive predictive value of the multiple-marker RT-PCR assay was 0.355 (95% CI, 0.192-0.546) for predicting non-SLN metastasis, which was lower than that of intraoperative diagnosis (0.813, 95% CI, 0.544-0.960).

CONCLUSIONS

The real-time RT-PCR assay could detect SLN metastasis in gastric cancer. However, the predictive value of the real-time RT-PCR assay was lower than that of precise histopathologic examination and did not outweigh that of our intraoperative SLN diagnosis.

Occult Tumor Cells in Lymph Nodes of Patients with Gastric Cancer: A Systematic Review on Their Prevalence and Predictive Role

BACKGROUND AND AIMS

The presence of lymph node (LN) metastasis is a key prognostic factor for gastric adenocarcinoma. However, even among patients without LN metastasis (N0), recurrence may occur. In some of these cases, occult tumor cells (OTC) are thought to play an important role. We aimed to determine the prevalence of OTC and its clinical relevance.

METHODS

We conducted a systematic review of studies in English published until September 2013 that addressed OTC prevalence and/or its clinical relevance. The studies were retrieved from the MEDLINE database.

RESULTS

We included 42 studies. The most frequently used methods for detecting OTC were immunohistochemical examination (IHC) and/or polymerase chain reaction (PCR) with a wide range of markers. Using IHC for OTC detection, in patients and in LN, the prevalence varied from 9 to 88% and 0.4 to 42%, respectively. With PCR, it ranged from 17 to 46% in patients, and from 3 to 33% in LN. In the studies assessing the predictive role of OTC in gastric cancer recurrence (n=24), 8 studies found no statistical association, while 18 concluded that OTC presence was associated with poorer prognosis. However, only 6 studies presented a significantly different 5-year survival rate between patients with and without LN micrometastasis.

CONCLUSIONS

OTC seems to occur in gastric cancer patients with a variable prevalence, depending on the definition, methods and setting. The majority of the retrieved studies (75%) evaluating the predictive role of OTC conclude that its presence is associated with a worse prognosis.

Current status and scope of lymph node micrometastasis in gastric cancer

Recently, lymph node micrometastasis has been evaluated for its prognostic value in gastric cancer. Lymph node micrometastasis cannot be detected via a usual pathologic examination, but it can be detected by using some other techniques including immunohistochemistry and reverse transcription-polymerase chain reaction assay. With the development of such diagnostic techniques, the detection rate of lymph node micrometastasis is constantly increasing. Although the prognostic value of lymph node micrometastasis remains debatable, its clinical impact is apparently remarkable in both early and advanced gastric cancer. At present, studies on the prognostic value of lymph node micrometastasis are evolving to overcome its current limitations and extend the scope of its application.

Prognostic value of CEA and CK20 mRNA in the peritoneal lavage fluid of patients undergoing curative surgery for gastric cancer

BACKGROUND

Peritoneal recurrence is the most common type of recurrence in gastric cancer. Although cytological examination of peritoneal lavage fluid has been used to predict peritoneal spread, peritoneal recurrences often occur even in patients with negative cytology. Our previous retrospective study suggested that reverse transcriptase-polymerase chain reaction (RT-PCR) using peritoneal lavage fluid may be useful for predicting peritoneal recurrence in patients with negative cytology. This prospective study was conducted to validate the clinical impact of this RT-PCR method.

METHODS

From July 2009 to June 2012, a total of 118 cT2-4 gastric cancer patients underwent surgery. Since 14 patients were ineligible because they had incurable factors, the remaining 104 eligible patients were evaluated for carcinoembryonic antigen (CEA) and cytokeratin 20 (CK20) messenger RNA (mRNA) using RT-PCR. If either CEA or CK20 mRNA was detected by RT-PCR, the patient was defined as PCR-positive as in our previous study. The association between recurrence-free survival (RFS) and background factors was analyzed using Cox proportional hazards models.

RESULTS

Of 104 patients, 16 (15.4 %) were positive for either CEA or CK20. PCR-positive patients had significantly worse RFS than PCR-negative patients (log-rank p = 0.007). Regarding the pattern of recurrence, 4 of 16 (25 %) PCR-positive patients and 2 of 88 (2 %) PCR-negative patients had peritoneal recurrence (p < 0.001), but there were no significant differences in recurrence at other sites. Cox multivariate analysis indicated only PCR-positivity as a significant predictor of poor RFS (p = 0.029).

CONCLUSION

This prospective study demonstrated that CEA and CK20 PCR results could predict peritoneal recurrence after curative surgery.

Prognostic value of genetic detection using CEA and MAGE in peritoneal washes with gastric carcinoma after curative resection: result of a 3-year follow-up

Peritoneal metastasis is the most frequent cause of death in patients with gastric cancer. Reverse transcriptase-polymerase chain reaction (RT-PCR) assay of peritoneal washes has been used to predict peritoneal metastasis of gastric carcinoma. We applied carcinoembryonic antigen (CEA) and melanoma-associated gene (MAGE) RT-PCR for the detection of peritoneal metastasis of gastric carcinoma after curative surgery and evaluated its clinical significance. Peritoneal washes were obtained from 117 patients with gastric carcinoma. MAGE A1-A6 and CEA RT-PCR were performed, and the results were evaluated according to their clinicopathologic characteristics. Three-year follow-up clinical studies were periodically performed, and disease-free survival rates were retrospectively investigated using the medical records. Among 117 peritoneal fluids, 11 cases (9.4%) revealed MAGE expression and 38 cases (32.5%) revealed CEA expression. When focusing on recurrence rates, RT-PCR-positive had much higher recurrence rates than RT-PCR-negative cases (32.5% vs 5.2%, P < 0.01). Univariate analysis revealed that depth of invasion, lymph node metastasis, tumor node metastasis (TNM) stage, Lauren classification, and MAGE and CEA expressions were independent prognostic factors for recurrence. In a multivariate analysis, MAGE expression and TNM stage were significantly and independently related to recurrence in patients who underwent curative resection. MAGE expression was determined to be the most important prognostic factor for recurrence (hazard ratio: 12.487, P < 0.01). It is feasible to identify free cancer cells in peritoneal lavage by using a MAGE A1-A6 and CEA RT-PCR. MAGE RT-PCR results disclosed significant associations with peritoneal recurrence and proved to be the most important factor for the recurrence rate in patients with gastric carcinoma who had undergone radical resection.

Evaluation of focused sentinel lymph node RT-qPCR screening for micrometastases with the use of the Maruyama computer program

Background

In this preliminary study, we investigated the sensitivity and specificity of reverse transcriptase (RT)-qPCR lymph node (LN) metastases detection, the accuracy of intraoperative dye navigation, and the incidence of micrometastasis (MM) detection with this protocol, compared to other published studies.

Methods

A total of 23 patients were enrolled in the study. The first stained LN was analyzed using RT-qPCR for carcinoembryonic antigen (CEA) and cytokeratin 20 (CK-20) expression, as markers for MM involvement. The Maruyama computer program was used to determine the most likely first metastatic site. These results were compared with the actual staining patterns to evaluate whether the first draining LN was extracted. We analyzed the correlations between MM and tumor characteristics. The incidence of MM detected with the present method was compared to other studies, as markers of the accuracy of the present protocol.

Results

At 35 threshold cycles, the RT-qPCR had a negative predictive value of 100 % and a positive predictive value of 83.3 %. MM were detected in 4 out of 14 node-negative patients (28.6 %). The extracted sentinel LN coincided in 76.9 % of cases with the most probable first metastatic LN predicted by the Maruyama program. MM were found more frequently in these ‘high-risk’ LNs. Significant differences were found in the Lauren’s histological type distribution and the age distribution among the MM-positive and MM-negative groups.

Conclusion

Our preliminary results confirm that RT-qPCR is an accurate method of MM detection, that the dye navigation enables the determination of the first draining LN, and that the incidence of MM detection with this focused sentinel LN protocol is comparable to other studies.

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.

Clinical significance of lymph node micrometastasis in gastric cancer

Recently, the existence of lymph node micrometastasis (LNM), including isolated tumor cells, has been focused on during the development of molecular diagnostic tools for lymph node metastasis in various malignant neoplasms. In particular, immunohistochemistry and reverse transcription-polymerase chain reaction have been reported to be available for the detection of LNM in gastric cancer. However, at present, the clinical significance of LNM remains unclear in patients with gastric cancer. Therefore, we cannot strategically make light of this issue in clinical management. Currently, minimally invasive treatments, such as endoscopic submucosal dissection and laparoscopic surgery with personalized lymphadenectomy, are widely performed in consideration of postsurgical quality of life (QOL). However, it is important to maintain the balance between QOL and curability when selecting surgical treatments for patients with gastric cancer. If minimally invasive surgery based on LNM status was established for patients with early gastric cancer, it could be performed safely. We reviewed the clinical significance of LNM as an important strategic target in patients with gastric cancer.

Analysis for the combination expression of CK20, FABP1 and MUC2 is sensitive for the prediction of peritoneal recurrence in gastric cancer

Prediction of peritoneal recurrence in gastric cancer patients is important for application of adjuvant chemotherapy. After surgery, occasional patients have peritoneal recurrence despite negative cytology of the peritoneal washings. Thus, molecular detection of a subliminal number of cancer cells in peritoneal washings may overcome the sensitivity limitation of conventional cytology. In this study, expressions of five specific marker genes, namely, TFF1, TFF2, CK20, FABP1 and MUC2, were evaluated for their usefulness as markers of micro-dissemination. It was found that reverse transcriptase-polymerase chain reaction for these five genes yielded results highly specific for the depth of invasion and disease stage. Furthermore, the expression of CK20, FABP1 and MUC2 was a reliable prognostic indicator of peritoneal metastasis. Our results suggest that evaluation of the expression of CK20, FABP1 and MUC2 in peritoneal washings is a useful tool for identifying patients at high risk of peritoneal recurrence who may need adjuvant chemotherapy.

Molecular detection of sentinel node micrometastases in patients with clinical N0 gastric carcinoma with real-time multiplex reverse transcription-polymerase chain reaction assay

PURPOSE

Described is a novel real-time multiplex reverse transcription-polymerase chain reaction (RT-PCR) assay suitable for intraoperative detection of micrometastasis (MM) in sentinel nodes (SNs) dissected from patients with clinical N0 (cN0) gastric carcinoma.

METHODS

One hundred three patients with gastric cancer, who were preoperatively diagnosed with cN0 and clinical T1 or T2, were enrolled. The patients underwent SN mapping followed by standard radical gastrectomy with lymph node dissection. In addition to all SNs, non-SNs (NSNs) within the SN lymphatic basin and NSN from a different lymphatic basin were randomly sampled. All SNs and NSNs were examined by routine histologic diagnosis and RT-PCR for the expression of cytokeratin (CK) 19, CK20, and carcinoembryonic antigen (CEA).

RESULTS

The RT-PCR assay and histologic examination were performed in 512 SNs and 299 NSNs from 103 patients. Pathologic l lymph node metastasis was revealed in 13 (12.6%) of 103 patients. All metastatic lymph nodes were identified within SNs. SNs of these 13 patients had positive findings on RT-PCR. Twenty-eight (27.2%) of 103 patients had negative histopathology but positive findings on RT-PCR. In 7 patients (6.8%), SNs were negative but NSNs were positive on RT-PCR. RT-PCR-positive NSNs were present in the same station as corresponding SNs in 3 of these 7 patients and in the same basin as SNs in 4 patients.

CONCLUSIONS

The real-time multiplex RT-PCR assay is a useful tool for the detection of MM in SNs and NSNs in patients with gastric cancer.

Oncofetal protein, IMP-3, a potential marker for prediction of postoperative peritoneal dissemination in gastric adenocarcinoma

BACKGROUND

The aim of this study was to determine the expression of insulin-like growth factor-II messenger RNA (mRNA)-binding protein-3 (IMP-3) and its clinical significance in gastric cancers, as well the prognostic value of its expression in the peritoneal lavage fluid after surgery.

METHODS

IMP-3 expression was examined by immunohistochemistry in 96 primary gastric tumors. IMP-3 mRNA expression in peritoneal lavage fluid obtained at laparotomy was determine by real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

Positive staining for IMP-3 was observed in 74% (71/96) of the tumors. IMP-3 expression in gastric tumors correlated significantly with worst overall survival (OS) and recurrence-free survival. Multivariate analyses identified pathological N stage and IMP-3 expression as significant independent prognostic factors for disease-free survival. Eight (28%) of 36 peritoneal lavage samples were cytologically negative but positive for IMP-3 mRNA expression by RT-PCR. The OS of patients with IMP-3-positive peritoneal lavage was significantly worse than of those with negative expression.

CONCLUSIONS

IMP-3 expression in primary gastric tumors was an independent poor prognostic factor. IMP-3 mRNA expression in peritoneal lavage fluid was a predictor of recurrence after surgery in gastric cancer and a marker of poor prognosis.

Prognostic significance of MAGE in peritoneal washes in gastric carcinoma patients without peritoneal metastasis: results of a 5-year follow-up study

GOALS

The RT-PCR assay of peritoneal washes has been used to predict peritoneal metastasis of gastric carcinoma. We used melanoma associated gene (MAGE) RT-PCR to detect peritoneal metastasis of gastric carcinoma after curative surgery and evaluated its clinical significance.

METHOD

Eighty-four peritoneal washes and 23 tumor and normal tissues were obtained from 84 gastric carcinoma patients. MAGE A1-A6 RT-PCR was carried out, and the results were evaluated according to their clinicopathologic characteristics. Five-year follow-up clinical studies were carried out periodically, and overall survival rates were retrospectively investigated using medical records.

RESULTS

For the paired tumor and normal tissues, MAGE expression rates were 65.2% and 4.3%, respectively. In peritoneal fluids, 11 cases (13.1%) revealed MAGE expression, and higher MAGE expression rates were observed with young age, deeper invasion, and advanced stages of tumor groups. MAGE-positive cases had much higher recurrence rates than MAGE-negative cases (45.5% vs. 9.6%, P<0.002). Among T-stage, N-stage, and MAGE expression; MAGE expression was determined to be the most important prognostic factor for overall survival rate by Cox proportional hazard model analysis.

CONCLUSION

MAGE RT-PCR results for peritoneal fluid disclosed significant associations with peritoneal recurrence of gastric carcinoma and proved to be the most important factor for overall survival rate in gastric carcinoma patients who had undergone radical resection.

Study on lymph node metastasis correlated to lymphangiogenesis, lymphatic vessel invasion, and lymph node micrometastasis in gastric cancer

BACKGROUND

This study aimed to evaluate the clinical significance of lymphangiogenesis, lymph vessel invasion (LVI), and lymph node (LN) micrometastasis (LNMM) in patients with gastric cancer.

METHODS

The influences of the expression levels of LVI, lymph vessel density (LVD) by D2-40 immunohistochemical (IHC) staining (n=68), LNMM (including CK 20 and CK pan immunostainings, n=51) on the clinicopathologic profiles and the prognosis were analyzed.

RESULTS

The higher positive rate of LVI-IHC was related to deeper invasion (P=0.044), later TNM stage (P=0.003), and more extensive LN metastasis (LNM, P=0.000). The level of LVD was significantly associated with venous invasion (P=0.037), later TNM stage (P=0.020), positive LVI-HE (P=0.040), positive LVI-IHC status (P=0.001), and severer LNM (P=0.001). Better prognosis in LVI negative group than LVI positive group has been identified. The survival rate of the group with LVD≥15/field was significantly lower than that in the group with LVD≤14/field (P=0.032). Invasion depth, N stage, LNM, blood vessel invasion, or LVI was respectively an independent prognostic factor to 3-y survival rate. The incidence of patients with LNM and metastasized LNs increased respectively from 74.5% (38/51) by HE staining to 88.2% (45/51) by CK immunostaining and from 32.0% (253/791) to 41.5% (328/791) (P=0.001). The increment of LNMM was correlated to larger tumor diameter (P=0.001), deeper invasion (P=0.018), LNM (P=0.001) and later TNM stage (P=0.012), positive LVI (P=0.04). Meanwhile, the evaluation on LNMM revealed the migration of LN stage (N(0)→N(1) in seven patients, N(1)→N(2) in six patients, and N(2)→N(3) in one patient), and TNM stage (I(b)→II in four patients, II→III(a) in 4 patients, III(a)→III(b) in 3 patients, and III(b)→IV in one patient). Survival analysis demonstrated that better prognosis in patients without LNM and/or LNMM.

CONCLUSION

Our immunohistochemical analyses using antibodies of D2-40 and CK, including both CK 20 and CK pan, detected a higher incidence of LVIs and LNMs in gastric cancer specimens. This study shows close correlations among lymphangiogenesis related factors, such as LVI, LVD, and LNMM, and patients' prognosis after surgery. Therefore, immunohistochemical evaluations of these factors could be used for the accurate determination of tumor aggressiveness.

Detection of micrometastases in sentinel node navigation surgery for gastric cancer

Although lymph node metastasis is one of the important prognostic factors for patients with gastric cancer, the clinical significance of micrometastasis remains controversial. In the 6th edition of the TMN classification, micrometastases were classified as micrometastasis (MM) and isolated tumor cells (ITC) according to its greatest dimension. The accurate diagnosis of micrometastases is required when considering less invasive surgery, especially in early stage of gastric cancer. Since generating useful information about micrometastases by conventional RT-PCR is time-consuming, this procedure is not useful for rapid diagnosis during surgery. Recently some new methods of genetic diagnosis have reduced the amount of time required to obtain information about micrometastases in lymph nodes to 30-40 min. Such methodology can be clinically applied during less invasive surgery. The sentinel node (SN) concept has recently been applied to gastric cancer and SN navigation surgery (SNNS) is ideal for reduction of lymphadenectomy in patients with early gastric cancer. However, we should think about some conditions to establish SN concept for gastric cancer: the particle size of radioisotope, relationship between metastatic area and RI uptake, and the diagnosis of micrometastases by various method such as histological examination, immunostaining and RT-PCR. Here, we described the current status of MM and ITC in the lymph nodes and the SN concept in gastric cancer.

Expression of melanoma-associated antigens in oral squamous cell carcinoma

BACKGROUND

Melanoma-associated antigens-A (MAGE-A) are expressed in a variety of tumors but not in normal tissues. Thus, their detection is highly specific to cancer cells, which makes them potential targets for the diagnosis, prognosis and also immunotherapy of neoplastic diseases.

METHODS

To determine the expression pattern and potential role of MAGE-A antigens in oral squamous cell carcinoma (OSCC), expression patterns of MAGE-A1-A6 and A12 were analyzed in 55 OSCC and 20 healthy oral mucosa using high-sensitive reverse transcription-nested polymerase chain reaction (RT-nPCR).

RESULTS

The 85.45% of tumor specimens expressed at least one of these genes. A significant correlation between the expression of MAGE-A1-A6 and A12 and malignancy was ascertained (P = 0.0001). On the contrary, none of the normal mucosal specimens expressed one of the MAGE-A subtypes. Antigen expression did not correlate with clinicopathological parameters, such as TNM classification, grading and clinical stage of OSCC.

CONCLUSIONS

Multiple simultaneous detection of MAGE-A1-A6 and A12 expression has been found to be more specific and sensitive than the detection of single MAGE-A antigen for the diagnostic and prognostic evaluation of OSCC. In addition, monitoring the expression of several MAGE-A subtypes may determine suitable immunotherapeutic targets. Subsequently, coexpressed genes may be warranted for developing polyvalent vaccines.

Genetic detection of free cancer cells in the peritoneal cavity of the patient with gastric cancer: present status and future perspectives

The purpose of this review is to examine the current status and future perspectives of the molecular analysis of peritoneal lavage fluid in patients with gastric cancer. During the past 10 years, the polymerase chain reaction (PCR) has been applied for the molecular detection of free cancer cells in the abdominal cavity of patients with gastric cancer, and its clinical significance in establishing the presence of peritoneal dissemination has been assessed by several groups especially in Japan. The majority of these studies have confirmed the predictive value of the molecular detection of peritoneal metastasis and recurrence using peritoneal lavage fluid. Based on these findings, since April 2006, the genetic diagnosis of body fluids has been included in the Japanese Government public health insurance program for patients with solid tumors. However, there are still many obstacles to overcome before the genetic diagnosis of micrometastasis can be considered a routine laboratory assay. Here we review the importance of the molecular detection of cancer cells in the abdominal cavity, and the molecular techniques used for such diagnosis; we also provide some clinical examples to illustrate the value of molecular diagnosis.

Cytokeratin 17 mRNA expression has potential for diagnostic marker of oral squamous cell carcinoma

PURPOSE

Determination of marker for identification of oral squamous cell carcinoma (OSCC) is important for early diagnosis and individual therapy. Cytokeratins (CKs) like CK 19 and CK 20 are known to be useful diagnostic and prognostic markers for solid tumors. The aim of this study was to evaluate the relevance of further CKs for diagnosis of OSCC.

MATERIALS

In 10 OSCC and 5 normal mucosal samples, the expression patterns of 31 CK genes were examined by cDNA microarray in order to identify CKs with most pronounced over-expression. The results were verified for CK 17, CK 19, and CK 20 in addition to 46 OSCC samples by relative quantification (RQ) using SYBR green real-time reverse transcriptase polymerase chain reaction (RT qPCR). A correlation of the CK expressions with the tumor classification was carried out.

RESULTS

cDNA microarray analyses showed that out of all CKs, CK 17 was up-regulated strongest in OSCC compared to normal samples, and over-expression was most significantly associated with diagnosis (P = 0.002). Expression rates of CK 19 and CK 20 were not significantly different between OSCC samples and normal samples. In 56 samples analyzed by real-time RT qPCR, CK 17 was over-expressed in 53 (94.6%), CK 19 in 18 (32.1%), and CK 20 in 7 (12.5%). The over-expression of CK 17 was significantly associated with metastases of neck lymph nodes (P < 0.05). CK 19 was significantly over-expressed in T3 and T4 OSCC, in stage III and IV patients (P < 0.05), and in poorly differentiated OSCC (P < 0.03). The over-expression of CK 20 was significantly associated with metastases of neck lymph nodes (P < 0.03). Determined by RQ, the mean value of CK 17 over-expression was significantly higher than that of the other CKs (P < 0.01), and was significantly associated with T1 and T2 OSCC (P < 0.03) and with stage I and II patients (P < 0.01).

CONCLUSION

CK 19 might be linked to the clinical progression and differentiation of OSCC, and CK 20 could be associated with metastases of neck lymph nodes in OSCC. Due to the significant up-regulation and the strong over-expression, CK 17 might be the most suitable marker for diagnosis of OSCC out of the CK-family.

Effect of lymph node micrometastases on prognosis of gastric carcinoma

AIM: To evaluate the relationship between lymph node micrometastases and prognosis of patients with gastric carcinoma and to evaluate the significance of the new assessment of nodal status in determining the pN categories in the 5th edition of the UICC TNM classification.

METHODS: A total of 850 lymph nodes from 30 patients with gastric carcinoma who underwent gastrectomy with lymphadenectomy were assessed by reverse transcription polymerase chain reaction assay in addition to histologic examination. Cytokeratin-20 gene marker was used in this assay.

RESULTS: Routine examination by HE staining confirmed metastasis in 233 lymph nodes from 20 patients. All these 233 lymph nodes were cytokeratin-20 positive. Moreover, lymph node micrometastases were detected in an additional 67 lymph nodes in 12 of these 20 patients. Lymph node micrometastases were also detected in 10 lymph nodes from 2 of 10 patients who had no obvious metastases identified by HE staining. Totally, lymph node micrometastases were identified by the reverse transcription polymerase chain reaction assay in 77 (12.5%) lymph nodes from 14 (46.7%) patients with gastric carcinoma. Of 27 patients who underwent curative resection, 7 (25.9%) were up-staged (fromIB stage to II stage in 1 patient, from IB stage to IIIA stage in 1 patient, from II stage to IIIA stage in 1 patient, from IIIA stage to IIIB stage in 1 patient, from IIIA stage to IV stage in 1 patient, from IIIB stage to IV stage in 2 patients). In a median follow-up of 32 (range 8-36) mo, Kaplan-Meier survival analysis showed significant improvements in median survival (22.86 ± 3.17 mo, 95% CI: 16.64-29.08 mo vs 18.00 ± 7.4 mo, 95% CI: 3.33-32.67 mo) of patients with negative lymph node micrometastases over patients with positive lymph node micrometastases (log-rank, P < 0.05).

CONCLUSION: Lymph node micrometastases have a significant impact on the current staging system of gastric carcinoma, and are significant risk factors for prognosis of patients with gastric carcinoma.

Rapid detection of metastasis of gastric cancer using reverse transcription loop-mediated isothermal amplification

Tailor-made surgeries for patients with solid malignancies have been under consideration on the basis of the development of new approaches for minor metastatic foci of malignant tumors. Accurate and reliable methods to detect metastases in biopsy specimens with certain rapidity are essential for the performance of these surgeries. The aim of this study was to develop a rapid and practical method to detect metastasis in specimens from patients with gastric carcinoma with the use of reverse transcription loop-mediated isothermal amplification (RT-LAMP) reaction, a novel technique for detecting mRNA expressions of targeted sequences with high sensitivity, specificity and rapidity under isothermal conditions. RT-LAMP primers to detect cytokeratin19 (CK19) mRNA were generated and 92 lymph nodes (LNs) obtained from 9 patients with gastric cancer were tested for tumor metastases with this technique. Among 92 LNs, 15 were metastasis-positive by routine histopathological examination. RT-LAMP reaction detected CK19 expression in all of the pathologically positive LNs and in 16 of 77 negative LNs. Nested RT-PCR assay for CK19 expression was also performed on 2 of the 9 cases including 32 LNs. The agreement rate of CK19 expression detection by RT-LAMP and RT-PCR analysis was 31/32 (97%). The RT-LAMP technique showed similar sensitivity to detect metastases as nested RT-PCR assay, with a rapidity comparable to that of intraoperative histopathological examination with frozen sectioning and hematoxylin and eosin staining. This method is expected to play an essential role in the performance of tailor-made surgeries in the near future.

Impact of Lymph Node Micrometastasis in Patients with Pancreatic Head Cancer

PURPOSE

The purpose of this study was to investigate the clinical significance of nodal micrometastasis in patients who underwent a curative operation for pancreatic cancer.

EXPERIMENTAL DESIGN

Fifty-eight patients underwent a macroscopically curative resection with extended lymph node dissection for pancreatic cancer. The total number of resected lymph nodes was 1,058, and 944 histologically negative lymph nodes were subjected to immunohistochemical staining to detect occult micrometastases.

RESULTS

Nodal micrometastases were detected immunohistochemically in 147 out of 944 resected histologically negative lymph nodes (15.6%). Forty-four of all 58 patients (75.9%) and 13 of the 23 histologically node-negative patients (56.5%) had nodal micrometastases. Nodal micrometastases existed in the N1 lymph node area most frequently, followed by the N2 and N3 lymph node areas. The distribution was similar to that of histologically metastatic lymph nodes. Ten out of 16 patients (62.5%) with histological N1, and 5 out of 16 patients (31.3%) with histological N2 had nodal micrometastases beyond the histological lymph node status. Three and 5-year survival rates of pN0 patients without lymph node nodal micrometastases were both 60.0%, while those with nodal micrometastases were 19.2% and 0%, respectively. There was statistically significant difference between the both groups (P = 0.041).

CONCLUSIONS

Nodal micrometastasis in pancreatic cancer existed in wider and more distant areas than histological lymph node status, and it was an unfavorable predictive factor, even in N0 patients.

STIR turbo SE MR imaging vs. coregistered FDG-PET/CT: Quantitative and qualitative assessment of N-stage in non-small-cell lung cancer patients

PURPOSE

To conduct a prospective comparison of the accuracy of short inversion time (TI) inversion-recovery (STIR) turbo spin-echo (SE) imaging and coregistered 2-[fluorine-18] fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) with computed tomography (CT) (coregistered FDG-PET/CT) to assess the N-stage in non-small-cell lung cancer (NSCLC) patients.

MATERIALS AND METHODS

A total of 115 consecutive NSCLC patients prospectively underwent CT, STIR turbo SE imaging, and FDG-PET, as well as surgical and pathological examinations. All STIR turbo SE images were obtained with a 0.9% saline phantom, which was placed alongside the chest wall of each patient, and coregistered FDG-PET/CTs were reconstructed using commercially available software. For quantitative assessments, the ratio of signal intensity (SI) of each lymph node to that of 0.9% saline phantom (lymph node-saline ratio [LSR]) and maximal standardized uptake value (SUV(max)) of each lymph node were calculated. Feasible threshold values were determined by using the receiver operating characteristic (ROC) curve-based positive test, and diagnostic capabilities of N-stage were compared by McNemar's test on a per patient basis.

RESULTS

When feasible, threshold values were adopted, quantitative sensitivity (90.1%) and accuracy (92.2%) of STIR turbo SE imaging were significantly higher than those of quantitative and qualitative sensitivities (76.7% and 74.4%) and accuracies (83.5% and 82.6%) of coregistered FDG-PET/CT on a per patient basis (P < 0.05).

CONCLUSION

STIR turbo SE imaging is at least as valid as coregistered FDG-PET/CT for quantitative and qualitative assessment of the N-stage for NSCLC patients.

The clinical significance of disseminated tumor cells in breast cancer

The presence of tumor cells in the bone marrow of primary breast cancer patients at surgery has been shown to be an independent prognostic indicator of relapse. Tumor cells have been detected either directly, using immunocytochemical staining, or indirectly, using reverse transcription-polymerase chain reaction (RT-PCR). Studies have been initiated to determine whether the presence of disseminated cells can be monitored during the therapy of patients with primary breast cancer, and thus potentially be used to predict relapse before overt metastases are detectable. Studies are also ongoing to improve methods of detection, such as immunobead enrichment followed by staining and real-time RT-PCR, and to find alternative markers for the disseminated cells. Studies of patients with overt metastases have shown that there is a large tumor load in the peripheral blood and that this predicts overall survival. This article reviews the published literature on studies carried out in both primary and metastatic breast cancer patients, the methodologies and markers used, and improvements in detection methodologies that are being investigated including real-time RT-PCR, novel markers, enrichment and automated image analysis.

Rapid identification of UCA1 as a very sensitive and specific unique marker for human bladder carcinoma

PURPOSE

The most common genitourinary malignancy in China is bladder transitional cell carcinoma (TCC). Early diagnosis of new and recurrent bladder cancers, followed by timely treatment, will help decrease mortality. There are currently no satisfactory markers for bladder cancer available in clinics. Better diagnostic methods are highly demanded.

EXPERIMENTAL DESIGN

In this research, we have used comprehensive expressed sequence tag analysis, serial analysis of gene expression, and microarray analysis and quickly discovered a candidate marker, urothelial carcinoma associated 1 (UCA1). The UCA1 gene was characterized and its performance as a urine marker was analyzed by reverse transcription-PCR with urine sediments. A total of 212 individuals were included in this study, 94 having bladder cancers, 33 ureter/pelvic cancers, and 85 normal and other urinary tract disease controls.

RESULTS

UCA1 was identified as a novel noncoding RNA gene dramatically up-regulated in TCC and it is the most TCC-specific gene yet identified. The full-length cDNA was 1,439 bp, and sequence analysis showed that it belonged to the human endogenous retrovirus H family. Clinical tests showed that UCA1 assay was highly specific (91.8%, 78 of 85) and very sensitive (80.9%, 76 of 94) in the diagnosis of bladder cancer and was especially valuable for superficial G2-G3 patients (sensitivity 91.1%, 41 of 45). It showed excellent differential diagnostic performance in various urinary tract diseases without TCC.

CONCLUSIONS

UCA1 is a very sensitive and specific unique marker for bladder cancer. It could have important implications in postoperative noninvasive follow-up. This research also highlights a shortcut to new cancer diagnostic assays through integration of in silico isolation methods with translational clinical tests based on RNA detection protocols.

K-19 mRNA RT-PCR in detecting micrometastasis in regional lymph nodes of gastric cancer

AIM: To investigate the value and prospect of RT-PCR in detecting micrometastasis in regional lymph nodes of gastric cancer.

METHODS: Histopathology was used and K19 mRNA expression was detected by RT-PCR in tumor tissues and lymph nodes from gastric cancer patients undergoing radical resection of gastric carcinoma.

RESULTS: K19 mRNA was expressed in all tumor specimens of 30 cases; of the 126 lymph nodes, 26 were histopathologically positive (20.6%), and 42 positive (33.3%) by RT-PCR. Amplification fragments of 460 and 540 bp were shown in all the tumor tissues and metastatic lymph nodes after K19 and β-actin RT-PCR, while only a 540 bp fragment appeared in the lymph nodes of non-tumor patients.

CONCLUSION: K19 mRNA RT-PCR is sensitive and specific in testing micrometastasis in regional lymph nodes of gastric cancer, and it is superior to routine histopathology.

Lymph node micrometastasis and its correlation with MMP-2 expression in gastric carcinoma

AIM: To examine matrix metalloproteinase-2 (MMP-2) expression in gastric cancer tissues and to evaluate its relationship with lymph node micrometastasis.

METHODS: The authors studied 850 lymph nodes resected from 30 patients with gastric carcinoma who underwent gastrectomy with lymphadenectomy using reverse transcription polymerase chain reaction (RT-PCR) assay in addition to H-E staining. MMP-2 expression of the tumor tissues was detected by immunohistochemical technique (EliVision^TM plus).

RESULTS: MMP-2 expression was positive in 21 (70%) cases and negative in 9 (30%) cases. No significant correlations were found between MMP-2 expression and other variables such as age, gender, tumor location, tumor diameter, Lauren classification and lymphatic invasion. In contrast, MMP-2 expression correlated significantly with depth of tumor infiltration (P = 0.022), lymph node metastasis (P = 0.030) and tumor differentiation (P = 0.043). Lymph node micrometastases were detected in 77 (12.5%) lymph nodes of 14 (46.7%) gastric carcinoma patients. MMP-2 expression was positive in 12 (85.7%) of the 14 patients with lymph node micrometastasis, and in 9 (56.3%) of the 16 patients without lymph node micrometastasis (P = 0.118).

CONCOUSION: Our results demonstrate that MMP-2 expression has significant correlation with tumor invasion, tumor differentiation and lymph node metastases. MMP-2 expression may be an important biological characteristics and significant prognostic parameter of gastric carcinoma. We also conclude that MMP-2 may participate in the development of lymph node micrometastasis of gastric carcinoma. Further investigations are needed to draw a conclusion.

Clinical value of genetically diagnosed lymph node micrometastasis for patients with oral squamous cell carcinoma

BACKGROUND

The purpose of this study was to investigate the incidence and clinical significance of genetically diagnosed lymph node micrometastasis for patients with oral squamous cell carcinoma (SCC).

METHODS

A total of 495 lymph nodes obtained from 21 patients with primary oral SCCs that had p53 mutations were examined for corresponding p53 mutations in lymph nodes using mutant allele-specific amplification (MASA).

RESULTS

Among 476 histologically negative nodes, 44 were scored as positive for metastasis by MASA. All 19 histologically positive lymph nodes were genetically positive. Four of the 10 pN0 cases and nine of the 11 pN-positive cases had genetically positive micrometastases. Four patients who had five or more genetically positive lymph nodes located in three or more levels, three with disease staged as pN0 or pN1, died of cancer.

CONCLUSIONS

These results indicate that a high rate of micrometastasis in cervical lymph nodes of oral SCCs and patients with multiple or lower neck spread of micrometastases have a poor prognosis; they should be treated with postoperative adjuvant therapy.

Biological significance of isolated tumor cells and micrometastasis in lymph nodes evaluated using a green fluorescent protein-tagged human gastric cancer cell line

PURPOSE

The biological significance of isolated tumor cells and micrometastasis in lymph node defined by the International Union against Cancer remains essentially unknown because of the lack of appropriate animal models. In the present study, we developed a lymph node micrometastasis model featuring a human gastric cancer cell line tagged with green fluorescent protein gene (GCIY-EGFP), which allows visualization of even isolated tumor cells in the development of metastasis without histologic procedure. Using this model, we investigated the effect of surgery and chemotherapy on the growth of early-phase metastasis formation in the lymph nodes.

EXPERIMENTAL DESIGN

The time course of spontaneous inguinal lymph node metastasis after s.c. inoculation of GCIY-EGFP cells into nude mice was examined with fluorescence dissecting microscopy. Then, the effects of surgical removal of the primary tumor with or without anti-asialo GM1 treatment or postoperative chemotherapy on the growth of isolated tumor cells and micrometastasis in the lymph nodes were examined.

RESULTS

GCIY-EGFP cells were found to metastasize spontaneously to the inguinal lymph nodes to form isolated tumor cells, micrometastasis, and, finally, develop macroscopic metastasis at 1 to 2, 3 to 5, and 5 weeks postinjection, respectively. When the primary tumors were removed within 2 weeks of inoculation, isolated tumor cells, but not micrometastasis, in the lymph nodes regressed by 4 weeks after surgery in all the mice examined (five of five). This spontaneous regression of isolated tumor cells was completely reversed by anti-asialo GM1 treatment, which could deplete natural killer cells effectively in nude mice. Chemotherapy following resection of the primary tumor at an early stage partially eliminated the remaining micrometastasis in the lymph nodes.

CONCLUSIONS

These results suggest that isolated tumor cells in the regional lymph nodes regressed by removal of the primary tumor mainly via natural killer cell-mediated antitumor activity and that micrometastasis in the lymph nodes could be effectively eliminated by the postoperative chemotherapy.

Detection and clinical implications of minimal residual disease in gastro-intestinal cancer

INTRODUCTION

Metastatic dissemination is an important factor for the prognosis of patients with gastro-intestinal cancer. Exact staging is crucial to determine appropriate multimodal therapeutic strategies. At present, the sensitivity of routinely performed diagnostic techniques is suboptimal for the detection of minimal residual disease (MRD) and occult metastases since the number of disseminated tumour cells (DTCs) is mostly marginal. To amend the verification of DTCs, immunohistochemical and molecular methods were applied to retrieve epithelial cell-specific proteins in non-epithelial tissue of different body compartments or fluids. Many groups have eagerly focussed on the identification of new markers and novel tests, yet specificity and sensitivity of these methods as well as robustness in the clinical setting are frequently missing.

MATERIALS AND METHODS

This review critically evaluates the prognostic impact of MRD in patients with pancreatic, colorectal and gastric cancer by outlining those studies showing diagnostic results of DTC detection in lymph nodes, bone marrow, venous blood and peritoneal lavage, some of which present novel strategies.

CONCLUSION

The analysed data concerning MRD in gastro-intestinal cancers reveal that results are undesirably heterogeneous. From a critical point of view, many clinical studies missed their chance because of small cohort size; moreover, methodological standardisation is generally lacking. On the other hand, the very encouraging results achieved so far, together with the comprehensive analyses of a few research groups, foster the prediction that DTC/MRD issues will soon expand the standard TNM classification.

Combined application of RT-PCR and immunohistochemistry on paraffin embedded sentinel lymph nodes of prostate cancer patients

The detection of tumor cells in the sentinel lymph node (SLN) is of great importance for the prognosis of cancer patients. At present, immunohistochemistry and RT-PCR for tumor marker expression are the most sensitive techniques available for this analysis. However, so far, most RT-PCR-based analyses of SLNs have been performed on fresh material, excluding a direct comparison with the (immuno)histologic results. In our view, this does not entirely aid routine diagnosis. We established an efficient method for RNA extraction and RT-PCR from paraffin sections of SLNs from prostate cancer patients and compared the results with the (immuno)histologic data of adjacent sections. Amplifiable RNA was obtained from 133 SLNs of 68 prostate cancer patients. Correlation of PSA-specific RT-PCR with (immuno)histologic findings showed a positive and negative predictive value of 83% and 100%, respectively, for the prostate cancer patients investigated. Four of 12 patients with biochemical relapse, but without (immuno)histologically detectable tumor cells were RT-PCR-positive for PSA. We found that single sections of paraffin-embedded SLNs are suitable for routinely performed RT-PCR. Combined with (immuno)histology, PSA-specific RT-PCR is a revealing supplementary technique for the detection of tumor cells in SLNs of prostate cancer patients.

Stage and mRNA expression of survivin in lymph node as prognostic indicators in patients with oral squamous cell carcinoma

Squamous cell carcinoma (SCC) is the most common malignant head and neck tumor and is responsible for more than 90% of head and neck cancers and accounts for 4.5% of all malignant tumors in males and 3.5% in females in South Korea. The purpose of this study was to investigate the correlation of suggested clinico-pathological prognostic factors such as gender, age, T score (T number in TNM), clinical stage, proliferation, invasion index, and lymph node metastasis to the survival of SCC patients in Korea. Furthermore, cytokeratin (CK), carcinoembryonic antigen (CEA), and recently documented apoptosis related protein, survivin, were analyzed by RT-PCR. In 113 patients, survival curves were estimated by the Kaplan-Meier method and nominal or numeric variable influence on survival was studied by Univariate and Multivariate Regression analysis (Cox proportional hazards model). Univariate analysis demonstrated that gender and age factor had no significant effect on survival rate. T score, on the other hand, significantly influenced survival and univariate analysis demonstrated that Stage 4 group had a significantly lower survival rate than the other stage groups but differentiation and invasion index factors had no significant effect on survival rate. Using a 50% cut-off point, patients with lower PCNA scores showed no survival advantages over those with higher PCNA scores but lymph node metastasis was a significant survival predictor in univariate analysis. In addition, lymph node CK and survivin mRNA expression have significant effects on OSCC patient survival rate. This means that prognostic value can be amplified by coincident analysis of T score, pathologically confirmed lymph node metastasis, and lymph node CK or survivin mRNA expression. Multivariate analysis using Cox's proportional hazards model, clinical TNM stage and lymph node survivin mRNA expression were independent OSCC prognostic factors, which support cancer staging based on the TNM as a powerful prognostic variable and lymph node survivin expression might provide predictive information for OSCC patient survival.

Expression of E-cadherin in gastric carcinoma and its correlation with lymph node micrometastasis

AIM: To examine the expression of E-cadherin in the primary tumor and to evaluate its relationship with lymph node micrometastasis (LNM).

METHODS: The authors studied 850 lymph nodes resected from 30 patients with gastric carcinoma who underwent gastrectomy with lymphadenectomy using reverse transcription polymerase chain reaction (RT-PCR) assay in addition to H&E staining. Cytokeratin-20 (CK-20) gene marker was used in this assay. The level of E-cadherin expression in the primary tumor was examined by immunochemical technique (EliVision^TM plus).

RESULTS: LNM was detected in 77 (12.5%) lymph nodes of 14 patients (46.7%) with gastric carcinoma. The incidence of LNM was significantly higher in the diffuse type (12 of 19 cases, 63.2%) than in the intestinal type of gastric carcinoma (2 of 11 cases, 18.2%, P = 0.026). The incidence of LNM also increased in accordance with the depth of tumor invasion. The loss of expression of E-cadherin in primary tumors was found in 14 (46.7) of 30 tumors. The absence of E-cadherin expression was significantly associated with the Lauren classification (P = 0.026), lymph node metastasis (P = 0.011), the grade of differentiation (P = 0.004) and the lymphatic invasion (P = 0.001). Expression of E-cadherin was negative in 10 (71.4%) of the 14 patients with LNM, and in 4 (25%) of the 16 patients without LNM (P = 0.026).

CONCLUSION: The current results indicate that the RT-PCR assay is useful for the detection of LNM and can significantly increase the detection rate of lymph node metastasis in patients with gastric carcinoma. The Lauren classification and depth of tumor invasion are significantly associated with lymph node micrometastases. Our findings also indicate that E-cadherin may play an important role in determining the growth type and differentiation of gastric carcinoma. The loss of E-cadherin expression may contribute to LNM.

Prediction of recurrence in advanced gastric cancer patients after curative resection by gene expression profiling

The prognosis of patients with advanced gastric cancer remains unfavorable. Even after curative resection, 40% of patients with advanced gastric cancer die of recurrence. Conventional clinicopathlogic findings are sometimes inadequate for predicting recurrence in individuals. Hence, we tried to construct a new diagnostic system, which predicts recurrence in patients with advanced gastric cancer after curative resection based on molecular analysis. Gastric cancer progression is a function of multiple genetic events that may affect the expression of large number of genes. We performed gene expression profiling with 2,304 genes in 60 advanced gastric cancer patients who underwent curative resection using a PCR array technique, a high-throughput quantitative RT-PCR technique. The diagnostic system, which was constructed from the learning set comprised of 40 patients with the most informative 29 genes, classified each case into a good-signature or poor-signature group. Then, we confirmed the predictive performance in an additional test set comprised of 20 patients, and the prediction accuracy for recurrence was 75%. Kaplan-Meier analysis revealed significant difference between the good-signature and the poor-signature group (p = 0.0125). Especially in patients with smaller tumor (< or = 5 cm), less developed LN metastasis (N(0,1)), or earlier stage (stages I and II), the prediction accuracy was high (88.9%, 84.6%, or 81.8%, respectively). Our diagnostic system based on systematic analysis of gene expression profiling can predict the recurrence at clinically meaningful level. By combining our system with conventional clinicopathologic factors, we can improve the prediction of recurrence in patients with advanced gastric cancer who underwent curative surgery.

Expression of vascular endothelial growth factor (VEGF)-C in preoperative biopsy specimens and metastatic foci of regional lymph nodes in submucosal gastric carcinoma

BACKGROUND: Vascular endothelial growth factor (VEGF)-C is implicated in lymphangiogenesis, however the exact role of VEGF-C in promoting lymphatic spread of cancer cells remains largely unknown. METHODS: The expression of VEGF-C was immunohistochemically determined in 97 endoscopic biopsy specimens from 46 patients with submucosal gastric carcinoma (SGC). Nodal metastases including micrometastasis and isolated tumor cells (ITC) were evaluated by immunohistochemical staining for cytokeratin in 1650 lymph nodes, and tumor cells in these metastatic nodes were also examined for VEGF-C expression. RESULTS: In biopsy samples, VEGF-C was positively detected in 21 (47%) patients. Metastases were identified in 46 (2.8%) nodes from 15 (33%) patients. Metastases were detected in 39 nodes by hematoxylin-eosin (H&E) staining and in additional 7 nodes as ITC by immunohistochemical staining. The rate of lymph node metastases was significantly correlated with VEGF-C expression in biopsy samples (p < 0.05). The positive and negative predictive values of VEGF-C in biopsy specimens for nodal metastasis were 44 %(10/21) and 80% (20/25), respectively. Among the 46 metastatic nodes, tumor cells in 29 (63%) nodes positive patients expressed VEGF-C, whereas those in 17 (37%) nodes did not. VEGF-C expression was high in macronodular foci in medullary areas, whereas more than half of ITC or micrometastasis located in peripheral sinus lacked the expression of VEGF-C. CONCLUSIONS: Despite the significant correlation, immunodetcetion of VEGF-C in endoscopic biopsy specimens could not accurately predict the nodal status, and thus cannot be applied for the decision of the treatment for SGC. VEGF-C may not be essential for lymphatic transport, but rather important to develop the macronodular lesion in metastatic nodes.

Clinical significance of bone marrow micrometastases in esophageal cancer

Using the reverse transcriptase-polymerase chain reaction (RT-PCR), we investigated the clinical significance of bone marrow micrometastases in patients with esophageal cancer. Bone marrow samples from 57 patients with esophageal cancer, who underwent esophagotomy, were investigated by specific RT-PCR for carcinoembryonic antigens (CEA). A total of 40 out of 57 patients (70.1%) were positive for CEA mRNA in the bone marrow. Among curatively resected cases, 34 of 50 patients (68.0%) were positive for CEA. Ten of 13 T1 patients (76.9%) were positive for CEA. Although the CEA-positive rate was high, there was no significant correlation between CEA positivity and any clinical characteristics. Among the 40 CEA-positive patients, 50% have shown recurrence so far. Detection of cancer cells in the bone marrow by RT-PCR may not always correspond to the malignant potential or other characteristics of the tumor. CEA-positive 'micrometastases' might actually represent isolated circulating tumor cells without much biological significance.

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.

Significance of isolated tumor cells in lymph nodes among gastric cancer patients

PURPOSE

To determine the frequency and prognostic impact of isolated tumor cells (ITC) in regional lymph nodes judged to be tumor free in conventional histopathology among gastric cancer patients.

METHODS

Among 161 patients who underwent gastrectomy and D2-lymphadenectomy, 56 were staged pN0(35%). Archival paraffin blocks of 1148 resected regional lymph nodes of those pN0 patients were reevaluated for ITC using monoclonal antibody Ber-EP4. Patients with and without ITC were compared with regard to the distribution of various clinicopathological factors. Prognostic impact of ITC was tested in uni- and multivariate analysis.

RESULTS

Of 56 pN0 patients, 33 (59%) exhibited single Ber-Ep4 immunoreactive cells or small cell clusters in at least one lymph node. The occurrence of ITC was not dependent on other clinicopathological factors. ITC impaired patients' prognoses significantly in uni- as well as multivariate analyses [estimated 5-year survival rate: 82% for pN0((i-))vs 58% for pN0((i+))(p = 0.059) and 15% for pN1/2 (p = 0.0005 and p < 0.0001, respectively)].

CONCLUSION

ITC are a frequent event in apparently tumor-free lymph nodes of gastric cancer patients and are overlooked by conventional histopathology. They are encountered even in limited stages of disease and impair patients' prognoses. This should be borne in mind when advocating local resection for early gastric cancer.

Metastases in Mediastinal and Hilar Lymph Nodes in Patients with Non–Small Cell Lung Cancer: Quantitative and Qualitative Assessment with STIR Turbo Spin-Echo MR Imaging

PURPOSE

To evaluate short inversion time inversion-recovery (STIR) turbo spin-echo (TSE) magnetic resonance (MR) imaging for detection of metastases in lymph nodes by using quantitative and qualitative analyses.

MATERIALS AND METHODS

One hundred ten patients (68 men and 42 women) with non-small cell lung cancer who ranged in age from 36 to 82 years (mean age, 64 years) were examined with respiratory-triggered STIR TSE MR imaging. Ratios of signal intensity in a lymph node to that in a 0.9% saline phantom (lymph node-saline ratios [LSRs]) for all lymph nodes were classified into three groups according to nodal short-axis diameter. LSRs of each group were compared by using pathologic diagnosis as the standard of reference. For quantitative analysis, the LSR threshold value for a positive test was determined on a per-node basis and tested for ability to enable a correct diagnosis on a per-patient basis. For qualitative analysis, signal intensities of lymph nodes were assessed by using a five-point visual scoring system. Results of quantitative and qualitative analyses were compared on a per-patient basis with McNemar testing.

RESULTS

In 110 patients, 92 of 802 lymph nodes were pathologically diagnosed as containing metastases, while 710 lymph nodes did not contain metastases. Mean LSR in the lymph node group with metastasis was higher than that in the group without metastasis (P <.05). When an LSR of 0.6 was used as the positive-test threshold at quantitative analysis, sensitivity was 93% (37 of 40 patients) and specificity was 87% (61 of 70 patients) on a per-patient basis. With a score of 4 as the positive-test threshold at qualitative analysis, sensitivity was 88% (35 of 40 patients) and specificity was 86% (60 of 70 patients) on a per-patient basis. There was no significant difference (P >.05) between results of quantitative and those of qualitative analysis.

CONCLUSION

Quantitative and qualitative analyses of STIR TSE MR images enable differentiation of lymph nodes with metastasis from those without. Qualitative analysis can substitute for quantitative analysis of STIR TSE MR imaging data.

Application of molecular diagnosis for detection of peritoneal micrometastasis and evaluation of preoperative chemotherapy in advanced gastric carcinoma

BACKGROUND

In advanced gastric cancer, peritoneal recurrence is the main cause of death after curative surgical resection. The aim of this report was to describe a novel approach for quantitative genetic diagnosis using peritoneal lavage for the identification of patients at high risk for peritoneal recurrence and for evaluation of the clinical response to intraperitoneal chemotherapy in advanced gastric cancer.

METHODS

Nineteen patients with advanced gastric cancer who underwent staging laparoscopy and intraperitoneal chemotherapy before surgical resection or systemic chemotherapy between June 1999 and September 2001 were enrolled in this study. All peritoneal lavage specimens, collected at both staging laparoscopy and gastrectomy, were subjected to real-time quantitative genetic diagnosis.

RESULTS

The reverse transcriptase polymerase chain reaction (RT-PCR) values decreased in 8 cases, stabilized as negative in 5, and increased in 6 during therapy. Patients whose RT-PCR values diminished and were ultimately negative survived except for one, and all but one patient whose values increased during treatment died of recurrence.

CONCLUSIONS

Quantitative evaluation of genetic changes can provide accurate, useful information on the effects of preoperative intra-abdominal chemotherapy and overall prognosis for patients with advanced gastric cancer.

Highly specific marker genes for detecting minimal gastric cancer cells in cytology negative peritoneal washings

Peritoneal wash cytology plays a pivotal role in the decision for gastric cancer treatment because advanced gastric cancer often turns out incurable with peritoneal metastasis. Molecular detection of minimal cancer cells from peritoneal washings may overcome the sensitivity boundary of conventional cytology and contribute to the prediction of the disease outcome. To select marker candidates out of ten thousands of genes, we performed microarray analyses in 12 gastric cell lines and 8 peritoneal washings of early stage cases. With 40 candidates selected by the above expression profiling, RT-PCR in 16 representative peritoneal wash samples was performed to identify genes specific to cytology positive samples. The finally selected five genes, CK20, FABP1, MUC2, TFF1, and TFF2, were then evaluated for their utility as a marker for minimal residual disease in 99 peritoneal wash samples. Nested RT-PCR using the five genes showed positive results highly specific to incurable cases (91-100%). With a high specificity, the combination of these five genes succeeded in identifying 6 out of 20 (30%) additional patients with all types of early recurrence that could not be predicted by the conventional method. The six newly identified recurrences included four non-peritoneal ones, showing that RT-PCR using the five genes without a real-time quantitative PCR technique contributes to the detection of minimal residual disease.