Detection Of Lymph Node Micrometastases Research Articles

Prediction of Biochemical Recurrence Based on Molecular Detection of Lymph Node Metastasis After Radical Prostatectomy

BackgroundMolecular detection of lymph node (LN) micrometastases by analyzing mRNA expression of epithelial markers in prostate cancer (PC) patients provides higher sensitivity than histopathological examination. ObjectiveTo investigate which type of marker to use and whether molecular detection of micrometastases in LNs was predictive of biochemical recurrence. Design, setting, and participantsLN samples from PC patients undergoing radical prostatectomy with extended LN dissection between 2009 and 2011 were examined for the presence of micrometastases by both routine histopathology and molecular analyses. Outcome measurements and statistical analysisThe mRNA expression of a panel of markers of prostate epithelial cells, prostate stem cell–like cells, epithelial-to-mesenchymal transition, and stromal activation, was performed by quantitative real-time polymerase chain reaction. The expression levels of these markers in LN metastases from three PC patients were compared with the expression levels in LN from five control patients without PC in order to identify the panel of markers best suited for the molecular detection of LN metastases. The predictive value of the molecular detection of micrometastases for biochemical recurrence was assessed after a follow-up of 10 yr. Results and limitationsProstate epithelial markers are better suited for the detection of occult LN metastases than molecular markers of stemness, epithelial-to-mesenchymal transition, or reactive stroma. An analysis of 1023 LNs from 60 PC patients for the expression of prostate epithelial cell markers has revealed different expression levels and patterns between patients and between LNs of the same patient. The positive predictive value of molecular detection of occult LN metastasis for biochemical recurrence is 66.7% and the negative predictive value is 62.5%. Limitations are sample size and the hypothesis-driven selection of markers. ConclusionsMolecular detection of epithelial cell markers increases the number of positive LNs and predicts tumor recurrence already at surgery. Patient summaryWe show that a panel of epithelial prostate markers rather than single genes is preferred for the molecular detection of lymph node micrometastases not visible at histopathological examination.

Septin 9 methylation analysis of lymph node micrometastases for predicting relapse of colorectal cancer

BackgroundMolecular markers for the detection of lymph node micrometastases of malignant tumors have been extensively investigated. However, epigenetic signatures have rarely been reported for identification of metastatic lymph nodes and disease relapse. Septin 9 is the most frequently reported hypermethylated gene in colorectal cancer (CRC). This study aimed to assess the clinical relevance of Septin 9 methylation in regional lymph nodes in recurrence/metastases of CRC. MethodsWe analyzed Septin 9 methylation of DNA from resected lymph nodes in 75 CRC patients with or without tumor recurrence using quantitative methylation-sensitive PCR (qMS-PCR). ResultsOf the 30 histologically negative lymph node CRC patients without recurrence (group 1), methylated Septin 9 was detected in 3 (10 %) cases. The positivity rate of methylated Septin 9 in group 2 containing 30 histologically node-negative CRC patients with recurrence was 30 % (9/30). For group 3, lymphatic invasion as well as tumor recurrence, 11 (73 %) out of 15 subjects had Septin 9 methylation-positive lymph nodes. Moreover, patients in group 3 had a higher level of methylated Septin 9 compared to subjects in group 1 and group 2 (p < 0.05). In addition, CRC patients with Septin 9 methylation in lymph nodes had significantly reduced survival (Log-rank P < 0.0001). ConclusionOur data support the predictive role of Septin 9 methylation analysis of lymph node micrometastases for tumor relapse after surgery.

The advantage of one-step nucleic acid amplification for the diagnosis of lymph node metastasis in colorectal cancer patients.

Generally, the postoperative examination of lymph nodes (LNs) is based on a microscopic examination of one hematoxylin and eosin (HE)‐stained slide; however, an examination of only one part of the LN might lead to incorrect staging of the tumor due to tissue allocation bias. Although multilevel sectioning and the use of immunohistochemistry (IHC) have improved the detection of micrometastases in LNs, this approach is laborious, time‐consuming, and costly. A novel molecular technique for the detection of LN metastases of tumors, called one‐step nucleic acid amplification (OSNA), is a rapid and semi‐quantitative examination quantifying the number of cytokeratin 19 (CK‐19) mRNA copies derived from a tumor. OSNA is already in clinical use for the diagnosis of LN metastasis in breast cancer patients; however, the use of OSNA is under investigation with promising results for colorectal cancer (CRC). The present review assessed recent studies on OSNA vs a histopathological examination and its implications for CRC staging and treatment. A total of 16 studies of OSNA in CRC yielded by a PubMed search were reviewed. Among them, seven studies evaluating the diagnostic performance revealed that OSNA had a high specificity (96.8%), high concordance rate (96.0%), and negative predictive value (98.6%) in a pooled assessment. In addition, four studies examining the utility of OSNA in sentinel LNs (SLNs) and two studies focusing on upstaging in pathologically node‐negative CRC patients were also reviewed. Multicenter prospective studies with a large cohort of CRC patients are warranted to reveal the benefits of OSNA in the future.

Left mediastinal node dissection after arterial ligament transection via video-assisted thoracoscopic surgery for potentially advanced stage I non-small cell lung cancer.

Left mediastinal node dissection during lung cancer surgery can be difficult because paratracheal and subcarinal lymph nodes are concealed by mediastinal structures. Arterial ligament transection (ALT) offers a wide surgical view of concealed mediastinal spaces, thus enabling extended en bloc lymph node dissection (LND). We analyzed surgical outcomes of patients who underwent extended LND after ALT via video-assisted thoracoscopic surgery (VATS) for potentially node-positive clinical stage I non-small cell lung cancer (NSCLC). We retrospectively investigated the medical records of 75 patients who had undergone extended mediastinal node dissection after ALT via VATS for potentially node-positive NSCLC at our centers during the period from September 2008 through November 2015. Operative data and rates of overall survival (OS), in addition to mortality and morbidity, were analyzed in relation pathological stage and nodal stage. Operative time was 238±58 minutes, and an average of 32.7±12.9 hilar and mediastinal lymph nodes were dissected. Lymph node metastases were detected in 34 patients (6 pN1 patients, 27 pN2 patients, and 1 pN3 patient). Mediastinal lymph node metastases were detected around the carina (stations 2L, 4L, and 7) in 19 of 27 patients with pN2 cancer. Nineteen patients had a total of 24 postoperative complications. Recurrent nerve paralysis was the most frequent complication (n=11) but resolved in eight patients during follow-up. Survival rates at 3 and 5 years were 92.2%/88.4%, 100.0%/60.0%, and 87.7%/81.0% for p-stage I, II, and III, respectively, and 92.2%/88.4%, 100.0%/60.0%, and 87.4%/80.7% for pN0, pN1, and pN2, respectively. Extended mediastinal node dissection after ALT allowed detection of lymph node micrometastases in selected patients with potentially node-positive left NSCLC and may improve outcomes.

Intraoperative imprint cytology versus histological diagnosis for the detection of sentinel lymph nodes in breast cancer treated with neoadjuvant chemotherapy

OBJECTIVES:To compare imprint cytology and paraffin section histology for sentinel lymph node detection in women with breast cancer treated with neoadjuvant chemotherapy.METHOD:A cross-sectional study and report of the sentinel lymph node statuses of 64 patients with breast cancer who underwent intraoperative imprint cytology and neoadjuvant chemotherapy in a referral cancer institute in Rio de Janeiro, Brazil, between 2014 and 2016.RESULTS:The mean age was 51 years. The most common histological type was invasive ductal carcinoma (93.75%), and the most common differentiation grade was 2 (62.5%). Overall, 153 lymph nodes were identified, with a mean of 2.39/case. Thirty-four lymph nodes tested positive for malignancy by imprint cytology, and 55 tested positive by histology. Of the 55 positive lymph nodes, 41 (74.5%) involved macrometastases, and 14 (25.5%) involved micrometastases. There were 21 false negatives with imprint cytology, namely, 7 for macrometastases and 14 for micrometastases, resulting in a rate of 17.6%. The sensitivity of imprint cytology was 61.8%, with a specificity and positive predictive value of 100%, a negative predictive value of 82.4% and an accuracy of 86.3%. The method presented null sensitivity for the identification of micrometastases.CONCLUSIONS:The false-negative rate with imprint cytology was associated with the number of sentinel lymph nodes obtained. The rate found for complete response to neoadjuvant chemotherapy was comparable to the rates reported in the literature. The accuracy of imprint cytology was good, and its specificity was excellent for sentinel lymph node detection; however, the method was unable to detect lymph node micrometastases.

A more sensitive detection of micrometastases of NSCLC in lymph nodes using the one‐step nucleic acid amplification (OSNA) method

Detection of tumor cells in lymph nodes (LNs) removed during the treatment of pulmonary tumor by radical surgery is limited by the possibilities of standard histopathological methods. The goal of this study was to obtain more accurate pTNM status by a more sensitive detection of micrometastases in LNs. A total of 885 LNs, an average of 13.8 LNs per patient, were removed during 64 surgeries. LNs from the same zone were pooled together as a group, five groups of LNs were examined in each patient. A total of 320 groups of LNs were examined. One-step nucleic acid amplification (OSNA) method was compared to standard histopathological examination with haematoxylin-eosin (H&E) staining and CK19 immunohistochemistry, specifically by an ultimate analysis of all intraoperatively removed LNs. Identical results for H&E and OSNA examinations were recorded in 286 groups of LNs (89.4%). In total, positive examinations were recorded in 27 groups of LNs (8.4%) using the OSNA method, which were H&E negative. In seven groups of LNs (2.2%), the H&E examination was positive, while OSNA method produced negative results. The OSNA examination led to a higher pTNM stage classification in 14 (21.9%) patients. The clinical significance remains the subject of follow-up research.

Comparing the Detection of Lymph Nodes Micrometastasis in Breast Cancer by the Hematoxylin and Eosin Staining Method (H&amp;E) and the Immunohistochemical Method (IHC)

Background: Breast cancer is the most common cancer in women. The most important factor in determining the prognosis and treatment of invasive breast cancer is axillary lymph nodes involvement. It is possible not to detect micrometastasis with applying staining tissues by the Hematoxylin and Eosin (H & E) staining method. Therefore, this study was conducted to determine and compare the detection of axillary lymph node micrometastasis in breast cancer by H & E and immunohistochemical (IHC) method. Methods: A cross sectional analytical study was carried out. By using census method, 80 female patients diagnosed with breast cancer and lymph node non-involvement were selected in Shahid Sadoughi General Hospital pathology ward, Yazd, up to 2016. IHC was performed to re-detect lymph node micrometastasis. The checklist was used to collect data of demographic, clinical, and pathological characteristics of the study population. The data collection was analyzed, using statistical software version SPSS-18, descriptive statistics, and Chi-Square analysis test. P value less than 0.05 was considered statistically significant. Results: Of the 80 samples using H & E staining method, no case was diagnosed with lymph node micrometastasis, but using IHC, 50 cases (62.5%) were found negative and 30 cases (37.5%) were found positive. The majority of tumors in the positive group had poorly differentiated grade and the difference between the tumor grade in both positive and negative group was statistically significant (P = 0.001). Also, the majority of tumors in the positive group were located in the upper-outer and lower-outer quadrant of breast and the difference between tumor locations in both positive and negative group was statistically significant (P = 0.001). Conclusions: According to the results, IHC is more beneficial than the H&E method to detect micrometastatic cells and to examine tissues that have high-grade tumors and also tumors located in upper-outer or lower-outer more possibility of metastasis.

Novel surgical approach based on the sentinel node concept in patients with early gastric cancer.

Recent prospective multicenter trials have demonstrated the clinical safety and efficacy of sentinel node navigation surgery (SNNS) in patients with early gastric cancer. Further, development of an intraoperative imaging system and an indocyanine green fluorescence imaging approach has been attracting attention as a novel tool for detection of the sentinel node (SN). The greatest advantage of an in vivo imaging system is that it visualizes SN and afferent lymphatic vessels from the primary tumor site more clearly than the conventional dye approach. Besides visualization of the SN, it is also essential to accurately assess the presence or absence of lymph node metastasis in the intraoperative management of SNNS. However, the clinical significance of lymph node micrometastasis (LNM) in patients with gastric cancer remains controversial. Reverse transcription‐polymerase chain reaction (RT‐PCR) is one of the representative assays used to identify LNM. A rapid RT‐PCR assay that completes the detection of LNM within approximately 40 minutes has recently been produced and applied in the clinical management of SNNS. From the viewpoint of surgical methods, modified laparoscopic and endoscopic cooperative surgery with non‐exposed approaches has recently been highlighted as a promising technique to prevent tumor dissemination caused by surgical procedures, and is likely to be clinically applied to SNNS in the future. When carrying out SNNS as a minimally invasive surgery, it is important to consider the balance between post‐surgical quality of life and curability. Future prospective studies on SNNS will greatly contribute to furthering its establishment as a beneficial procedure for patients with early gastric cancer.

Current status of lymph node micrometastasis in gastric cancer.

Lymph node metastasis is one of the most important prognostic factors in patients with gastric cancer. An inadequate number of dissected lymph nodes is an independent risk factor affecting recurrence, even in patients who are node negative. Oddly, certain early-stage patients still experience recurrence or metastasis within a short time, even if they have undergone standard radical mastectomy. Many researchers have attributed these adverse events to lymph node micrometastasis (LNM), which is defined as a microscopic deposit of malignant cells of less than 2 mm in diameter. With the development of diagnostic tools such as immunohistochemistry and reverse transcription-polymerase chain reaction, the rate of detection of LNM has been constantly increasing. Although there is no clear consensus about risk factors for or the definitive clinical significance of LNM, the clinical impact of LNM is remarkable in gastric cancer. For minimally invasive treatment in particular, such as endoscopic submucosal dissection and laparoscopic surgery, accurate diagnosis of LNM is regarded as the potential key to maintaining the balance between curability and safety. This review provides an overview of the definition, detection and significance of LNM in gastric cancer. We also summarize several attention-drawing controversies regarding the treatment of patients who may have LNM.

Lymph Node Micrometastases and In-Transit Metastases from Melanoma: In Vivo Detection with Multispectral Optoacoustic Imaging in a Mouse Model.

Purpose To study whether multispectral optoacoustic tomography (MSOT) can serve as a label-free imaging modality for the detection of lymph node micrometastases and in-transit metastases from melanoma on the basis of the intrinsic contrast of melanin in comparison to fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT). Materials and Methods The study was approved by the institutional animal care and use committee. Sequential MSOT was performed in a mouse B16F10 melanoma limb lymph node metastasis model (n = 13) to survey the development of macro-, micro- and in-transit metastases (metastases that are in transit from the primary tumor site to the local nodal basin) in vivo. The in vitro limit of detection was assessed in a B16F10 cell phantom. Signal specificity was determined on the basis of a simultaneous lymphadenitis (n = 4) and 4T1 breast cancer lymph metastasis (n = 2) model. MSOT was compared with intravenous FDG PET/CT. The diagnosis was assessed with histologic examination. Differences in the signal ratio (metastatic node to contralateral limb) between the two modalities were determined with the two-tailed paired t test. Results The mean signal ratios acquired with MSOT in micrometastases (2.5 ± 0.3, n = 6) and in-transit metastases (8.3 ± 5.8, n = 4) were higher than those obtained with FDG PET/CT (1.1 ± 0.5 [P < .01] and 1.3 ± 0.6 [P < .05], respectively). MSOT was able to help differentiate even small melanoma lymph node metastases from the other lymphadenopathies (P < .05 for both) in vivo, whereas FDG PET/CT could not (P > .1 for both). In vitro, the limit of detection was at an approximate cell density of five cells per microliter (P < .01). Conclusion MSOT enabled detection of melanoma lymph node micrometastases and in-transit metastases undetectable with FDG PET/CT and helped differentiate melanoma metastasis from other lymphadenopathies. (©) RSNA, 2016 Online supplemental material is available for this article.

Lymph Node Micrometastases are Associated with Worse Survival in Patients with Otherwise Node-Negative Hilar Cholangiocarcinoma.

BackgroundLymph node metastases on routine histology are a strong negative predictor for survival after resection of hilar cholangiocarcinoma. Additional immunohistochemistry can detect lymph node micrometastases in patients who are otherwise node negative, but the prognostic value is unsure. The objective of this study was to assess the effect on survival of immunohistochemically detected lymph node micrometastases in patients with node-negative (pN0) hilar cholangiocarcinoma on routine histology.MethodsBetween 1990 and 2010, a total of 146 patients underwent curative-intent resection of hilar cholangiocarcinoma with regional lymphadenectomy at two university medical centers in the Netherlands. Ninety-one patients (62 %) without lymph node metastases at routine histology were included. Micrometastases were identified by multiple sectioning of all lymph nodes and additional immunostaining with an antibody against cytokeratin 19 (K19). The association with overall survival was assessed in univariable and multivariable analysis. Median follow-up was 48 months.ResultsMicrometastases were identified in 16 (5 %) of 324 lymph nodes, corresponding to 11 (12 %) of 91 patients. There were no differences in clinical variables between K19 lymph node-positive and -negative patients. Five-year survival rates in patients with lymph node micrometastases were significantly lower compared to patients without micrometastases (27 vs. 54 %, P = 0.01). Multivariable analysis confirmed micrometastases as an independent prognostic factor for survival (adjusted Hazard ratio 2.4, P = 0.02).ConclusionsLymph node micrometastases are associated with worse survival after resection of hilar cholangiocarcinoma. Immunohistochemical detection of lymph node micrometastases leads to better staging of patients who were initially diagnosed with node-negative (pN0) hilar cholangiocarcinoma on routine histology.

Expression of lung-specific X protein in non small cell lung cancer lymph node metastasis and the clinical significance

Objective To investigate the detection of lymph node micrometastasis in stage Ⅰ nonsmall cell lung cancers (NSCLC) using lung-specific X protein (LUNX) mRNA as a marker based on reverse transcription-polymerase chain reaction (RT-PCR) and its relationship with the patho-clinical features and prognosis.Methods 52 patients underwent curative lobectomy,excluding pneumonectomy and Palliative resection.Curative lobeetomy included systemic lymph node reseetion,Which meant at least 6 mediastinal lymph node from 3 stations were reseeted.The expression of LUNX mRNA in each station of lymph node were examined by means of RT-PCR.LUNX mRNA was then used as a marker of lymph node micrometastasis.Analyses of relationship between lymph node micrometastasis and the pathoclinical features,overall survival and disease free survival were then carried out.Results The expression of LUNX mRNA:none was positive for all ten lymph nodes from benign diseases.All 52 lung cancer tissues showed positive expression,14.98％ of lymph nodes and 12.24％ of mediastinal lymph nodes showed positive expression,so that the LUNX stage was upgraded.Survival affecting factors included:LUNX stage (P ＜ 0.01),mediastinal lymph nodes micrometastasis (P ＜ 0.01),number of lymph nodes and mediastinal lymph nodes resected (P ＜ 0.05),pathological differentiation (P ＜ 0.05).Those with mediastinal lymph nodes micrometastasis had a 21.8 folds higher risk of death than those without (P ＜ 0.01).Conclusion The expression of LUNX mRNA in lymph nodes is related to overall survival and disease free survival,and is a reflection of lymph nodes micrometastasis.The subgroup of stage propidium iodide (PI) patients with high risks can be thus found.This technique is helpful in restaging patients more accurately.Survival can be improved if interference is applied in early stage. Key words: Non-small cell lung cancer; Lung-specific X protein; Lymphatic metastasis; Survival rate

Gastric carcinoma: stage migration by immunohistochemically detected lymph node micrometastases

Immunohistochemically detected micrometastases of the regional lymph nodes in previously pN0-classified gastric cancer have been incorporated in the TNM staging system. This study aims to determine the incidence of such micrometastases in gastric carcinoma and to investigate their impact on stage grouping and prognosis. Ninety-five patients with gastric carcinoma classified as pN0 by conventional histological examination were enrolled. All patients underwent gastric resection with regional lymphadenectomy between 2006 and 2010. A total of 2018 lymph nodes was obtained (median, 20 Lymph nodes) and immunohistostained with anti-pan cytokeratin antibody (KL1). Micrometastases were detected in regional lymph nodes by immunohistostaining in 16 out of all 95 patients. Fourteen patients were upstaged by micrometastasis-positive regional lymph nodes. Three patients demonstrated lymph nodes with isolated tumor cells alone. A significantly higher incidence of micrometastases was observed in patients with diffuse histologic type (p = 0.007) and total gastrectomy (p = 0.007). When isolated tumor cells were also regarded as lymph node involvement, the recurrence rate was significantly higher for node-positive than for node-negative patients and for those younger than 70 years (33.3 and 6.7 %, respectively; p = 0.026; n = 39). Overall survival analysis revealed no significant difference between micrometastasis-positive and micrometastasis-negative patients. Immunohistostaining of regional lymph nodes in node-negative gastric carcinoma patients leads to an increased detection of micrometastases with significant implications for the staging system. Although no impact on survival time was shown, the higher recurrence rate for node-positive patients younger than 70 years indicates a prognostic value of immunohistochemically detectable micrometastases.

Diagnosis of lymph node micrometastasis at the pN₀ stage of lung adenocarcinoma using a combination of markers.

This study aimed to detect micrometastatic tumor cells in the lymph nodes of patients with pN0 lung adenocarcinoma using a combination of thyroid transcription factor-1 (TTF-1) expression and cytokeratin 7 (CK7) expression and to investigate the association of lymph node micrometastasis with the clinicopathological characteristics of patients with lung adenocarcinoma. A total of 54 patients with pN0 lung adenocarcinoma and whose primary tumors were positive for both TTF-1 and CK7 expression were included in this study. In total, 893 lymph nodes were obtained from these 54 patients and were analyzed for micrometastasis by immunohistochemical staining with anti-CK7 and anti-TTF-1 antibodies. CK7- and TTF-1-positive cells were found in the lymph nodes of 9 (16.7%) of 54 patients, and 21 (2.4%) of 893 lymph nodes exhibited positivity for these factors. No cells positive for both CK7 and TTF-1 were detected in the 5 lymph nodes obtained from patients with benign lung tumors. Lymph node micrometastasis was found to be associated with the differentiation grade and primary tumor position (P < 0.05). The detection of lymph node micrometastasis by a combination of CK7 and TTF-1 immunohistochemical staining provides a more accurate assessment of tumor staging for pN0 lung adenocarcinoma.

Erratum to: The role of SHP-1 promoter 2 hypermethylation detection of lymph node micrometastasis in resectable stage I non-small cell lung cancer as a prognostic marker of disease recurrence

Erratum to: The role of SHP-1 promoter 2 hypermethylation detection of lymph node micrometastasis in resectable stage I non-small cell lung cancer as a prognostic marker of disease recurrence

The role of SHP-1 promoter 2 hypermethylation detection of lymph node micrometastasis in resectable stage I non-small cell lung cancer as a prognostic marker of disease recurrence

Despite adequate surgical management of stage I non-small cell lung cancer (NSCLC), many patients still relapse. Nodal micrometastases which cannot be detected by the standard hematoxylin and eosin (H&E) method are the postulated mechanism. We conducted a study of an epithelial-specific methylation marker, SHP-1 promoter 2 (SHP1P2) methylation, as a potential molecular marker to determine its association with a high risk of disease relapse. Lymph nodes from stage II-IIIA NSCLC patients were examined to explore the potential role of SHP1P2 methylation in detecting metastatic carcinoma according to H&E staining. Further study was done in lymph nodes from stage I NSCLC patients who underwent curative resection and follow-up at The King Chulalongkorn Memorial Hospital, Bangkok, Thailand. No adjuvant treatment was given, according to the standard treatment in that stage. Patients who relapsed within 40 months after resection were defined as high risk. The nodal SHP1P2 methylation level from stage II-IIIA NSCLC patients was significantly higher in the metastasis group, median 674 [0-3536] ng, compared with the no metastasis group, median 230 [0-3832] ng (p = 0.004). One-hundred and ninety-eight lymph nodes from stage I NSCLC patients were analyzed, including hilar and mediastinal nodes. With a median follow-up period of 65 [46-109] months, high SHP1P2 methylation levels of more than 140 ng in hilar lymph nodes were associated with early relapse, with sensitivity and specificity of 85 and 54 %, respectively (hazard ratio 5.3; 95 % confidence interval 5.0-5.6; p < 0.0001). A high level of SHP1P2 methylation of hilar lymph nodes from stage I NSCLC patients is associated with early relapse of disease.

Where will the concept of lymph node micrometastasis advance?

There are several morphological pathways by which lymph node metastasis can arise: invasion into a deeper layer; detachment of tumor cells from the primary tumor; infiltration into intramural lymphatics; flow to extramural lymphatics; arrival to afferent lymphatics of a marginal sinus; movement to the lymph node cortex; and implantation of tumor cells into the node and formation of metastasis. Some cancer cells move from an efferent lymphatic vessel to the next lymph node. In terms of the first step toward lymph node metastasis, a small number of cancer cells is thought to be related to the formation of metastasis. Recent research into biological aspects has elucidated various tumor characteristics. What kinds of tumor cells have metastatic potential? Many molecules in the pathways toward lymphatic metastasis are thought to be related. Once tumor cells invade the lymphatics, can all cells implant into lymph nodes? Numerous immune cells are originally present in the lymph nodes, and such cells fight and defend against the invasion of bacteria, viruses, tumor cells, and so on. Thus, it is speculated that only certain special cancer cells can implant and grow to form an overt metastasis. What are these special cancer cells? The recent concept of epithelial-mesenchymal transition and the stem cell theory seems to offer an important key to solving the properties of tumor cells. Tumor cells able to seed a metastasis must presumably have the ability to avoid immune defense cells. Further basic studies will elucidate the mechanisms underlying lymphatic metastasis. Meanwhile, in the clinical field, lymph node metastasis offers an important prognostic factor for gastrointestinal (GI) cancer. The presence of tiny lymph node metastasis, in the form of lymph node micrometastasis (LNM) that is not detectable by routine histological examination, has been reported in carcinomas of various organs. Although overt lymph node metastasis is thought to be related to prognosis, what is the relationship between LNM and prognosis? Recent advances in techniques such as immunohistochemistry (IHC) and reverse transcription-polymerase chain reaction (RT-PCR) have allowed the detection of LNM. Recently, LNM has been defined by the criteria of TNM classification and roughly divided in some categories according to the size of the metastatic foci or the method of detection. Clinical evaluation of LNM is somewhat difficult, because of the differences in study designs and methods of detection, such as the sample size, tumor stage of patients, number of removed nodes based on the area of lymph node dissection, use of immunohistochemistry, RTPCR, or other methods, and the kinds of antibodies or primers used. Several articles have discussed the clinical significance of LNM of GI cancer. The present review articles summarize the current knowledge of LNMs in GI cancer from the perspectives of both molecular and biological characteristics and clinical aspects. These articles will be helpful as an overview of the current understanding of LNM and areas requiring further investigation.

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.

Gene diagnosis of micrometastases in regional lymph nodes of patients with stage I non-small cell lung cancer: impact on staging and prognosis

The long-term survival of patients with completely resected stage I non-small cell lung cancer (NSCLC) is not optimal because of undetected lymph node micrometastasis at the time of surgery. The aim of this study is to evaluate the role of survivin and livin mRNA expression in histopathologically negative lymph nodes of stage I NSCLC patients as markers of micrometastasis. Clinical data and tissue samples of primary tumor and lymph nodes were collected from 44 patients with stage I NSCLC. Reverse-transcriptase-PCR (RT-PCR) was used to detect survivin and livin mRNA expression in these tumor and lymph node samples. Survivin mRNA was detected in all tumors, and livin mRNA was detectable in 39 of the 44 primary tumors. The cut-off values of survivin and livin mRNA levels for diagnosing micrometastasis in lymph nodes were set up according to the expression of survivin and livin mRNA in control lymph nodes. Fifteen (34.1 %) of 44 stage I NSCCL patients had micrometastasis in lymph nodes by survivin and/or livin mRNA positive expression. Survival analysis showed higher rate of cancer recurrences and tumor-related death in patients with lymph node micrometastasis (P < 0.001 and P = 0.001, respectively). Tumor-free survival and overall survival were significantly worse in patients with lymph node micrometastasis compared with those without such micrometastasis (P = 0.007 and P = 0.01, respectively). RT-RCR assay for survivin and livin mRNA can be considered as useful diagnostic tool for the detection of lymph node micrometastasis for stage I NSCLC patients.

Molecular diagnosis and prognostic significance of lymph node micrometastasis in patients with histologically node-negative non-small cell lung cancer

Lymph node metastasis is a major prognostic factor in resected non-small cell lung cancer (NSCLC). However, 30-40 % rate of recurrence after performing complete resection in node-negative patients suggests that their nodal staging is suboptimal. We aimed to evaluate the molecular diagnosis and prognostic significance of lymph node micrometastasis in patients with node-negative NSCLC. Primary tumor samples from 62 patients with resected stage I-IIB NSCLC were screened for fragile histidine triad (FHIT) and CDKN2A mRNA deletion using reverse transcriptase polymerase chain reaction (RT-PCR). The molecular alternations were found in tumors of 49 patients. A total of 269 lymph nodes from these 49 NSCLC patients with FHIT or/and CDKN2A deletion tumors were examined. Fifteen positive-control nodes and ten negative-control nodes were also analyzed for FHIT and CDKN2A mRNA deletion. Thirty-nine (22 %) and 22 (18 %) lymph nodes from the 49 patients with FHIT and CDKN2A mRNA deletion in primary tumor had FHIT and CDKN2A mRNA deletion, respectively. The types of FHIT and CDKN2A mRNA deletion in lymph nodes were identical with those in their primary tumors. By combination of two markers, 16 patients (32.7 %) were found to have nodal micrometastasis. Survival analysis showed that patients with nodal micrometastasis had reduced disease-free survival (P = 0.001) and overall survival (P = 0.002) rates. Multivariate analysis demonstrated that nodal micrometastasis was an independent predictor for worse prognosis. Thus, the detection of lymph node micrometastasis by FHIT and CDKN2A mRNA deletion RT-PCR will be helpful to predict the recurrence and prognosis of patients with completely resected stage I-IIB NSCLC.