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Consequently, both clinically positive and clinically negative patients frequently undergo neck dissections that may not be necessary. To address this potential overtreatment, sentinel lymph node SLN biopsy is currently being evaluated to provide better staging of the neck. However, to fully realize the potential improvement in patient care afforded by the SLN procedure, a rapid and accurate SLN analysis is necessary.
These considerations support the central importance of adequate regional lymph node collection to optimize molecular [ 4 , 5 , 21 ], as well as histological [ 2 , 3 , 90 , 91 ], detection of metastases to estimate tumor burden and improve risk stratification in colorectal cancer staging. J Natl Cancer Inst. The automated analysis with PVA provided perfect discrimination between histologically positive and benign lymph nodes and correctly identified two lymph nodes with micrometastatic tumor deposits. In head and neck cancer specifically, studies on molecular analysis of cervical lymph node metastasis have used a variety of techniques, including PCR amplification to detect p53 mutations 45 , immunohistochemistry staining with or without serial sectioning and histopathologic examination 14—16 , and standard RT-PCR—based analysis of tumor maker gene expression Guanylyl cyclase C is a marker of intestinal metaplasia, dysplasia, and adenocarcinoma of the gastrointestinal tract.
Seven markers were identified with good characteristics for identifying metastatic disease, and these were validated using a set of 26 primary tumors, 19 histologically positive lymph nodes, and 21 benign nodes from patients without cancer. The automated analysis with PVA provided perfect discrimination between histologically positive and benign lymph nodes and correctly identified two lymph nodes with micrometastatic tumor deposits.
Squamous cell carcinoma of the head and neck SCCHN frequently metastasizes to the regional lymph nodes and this is the strongest predictor of disease prognosis and outcome 1, 2. Whereas accurate staging of lymph nodes in the neck is essential for optimal patient management, current preoperative clinical methods, including newer radiographic techniques, are suboptimal and misdiagnose the presence or absence of cervical nodal metastasis in many patients 3—5.
Therefore, due to the low sensitivity of detecting nodal metastasis and the poor prognosis when these metastases are missed, the current management of the clinically node negative cN0 neck commonly includes routine elective neck dissection END with pathologic examination of the removed lymph nodes. END, or cervical lymphadenectomy done at the time of primary surgery for SCCHN for a cN0 neck, is associated with a significantly improved regional recurrence-free survival and lower incidence of distant metastases 6—9.
Furthermore, when END is not done, patients often present later with bulky neck metastases and unresectable disease. Because of the need to accurately stage the neck and to treat only those most likely to benefit from therapy, much interest has arisen recently to validate the technique of sentinel lymph node SLN mapping for SCCHN. This technique has the potential to define those cN0 patients in whom neck dissection is most appropriate i. When combined with intraoperative analysis of the SLN s , this approach could allow for definitive staging and surgical treatment in a single procedure.
For this goal to be fully realized, however, intraoperative SLN analysis must be both rapid and accurate. Unfortunately, although final pathology on fixed tissues with immunostaining if necessary in the case of SLNs is highly accurate, intraoperative frozen section examination is notoriously insensitive. Consequently, many patients have to undergo a second surgical procedure to complete lymph node dissection after definitive pathologic assessment identifies microscopic metastatic disease not evident on intraoperative analysis.
Performing a second surgery on the neck is an undesirable scenario because this would likely increase complications and morbidity and could delay the use of adjuvant therapy. This is in addition to the extra cost, discomfort, and psychological toll on the patient. Studies in many tumor types including esophageal cancer, colon cancer, breast cancer, melanoma, and SCCHN have showed the ability of an RT-PCR—based assay to detect histologically occult micrometastases 7, 9, 26— Whereas we are also interested in detection of occult disease by QRT-PCR, we have recently focused on application of this method to rapid, intraoperative analysis of SLNs.
Unfortunately, these reports used manual RNA isolation and QRT-PCR setup, and this is likely to be too labor intensive, prone to contamination, and variable for true clinical use in an intraoperative setting. Our goals in this study were to identify appropriate QRT-PCR markers for detection of metastasis to lymph nodes and to use the GeneXpert to show the feasibility of automated analysis in an intraoperative time frame. When applied to SLNs from patients with SCCHN, we show that this technology has the potential to accurately stage the neck and allow the surgeon to provide optimal treatment in a single procedure.
Of these specimens, eight sets of paired human head and neck primary tumors and tumor-containing metastatic lymph nodes from the same 8 patients with SCCHN were included in this study. Institutional review board—approved, written informed consent was obtained from all patients donating specimens for this study, either through the ENT Registry at the Department of Otolaryngology or the Esophageal Risk Registry at the Division of Thoracic and Foregut Surgery, University of Pittsburgh. These patients are similar to historical patients with SCCHN in our practice, with tumors distributed throughout all head and neck subsites.
In the 44 patients studied, histologically verified squamous cell carcinoma originated in one of the following primary sites: Clinical and demographic data of tumor and lymph node specimens obtained from patients with SCCHN in this study. An extensive literature and public database survey was conducted to identify any potential markers.
Our survey criteria were somewhat flexible but the goal was to identify genes with moderate to high expression in head and neck cancer and low expression in normal lymph nodes. In addition, genes reported to be up-regulated in head and neck cancer and genes with restricted tissue distribution were considered potentially useful. Finally, genes reported to be cancer specific, such as the cancer testis antigens and hTERT , were evaluated. Archived tissue from all patients in this study was reviewed by a specialized head and neck pathologist J. The screening was conducted in two phases.
All potential markers entered the primary screening phase and expression was analyzed in 6 primary tumors and 10 benign lymph nodes obtained from patients without cancer five RNA pools with 2 lymph node RNAs per pool. Markers that showed good characteristics for lymph node metastasis detection consistent, high expression in tumors and very low expression in benign nodes passed into the secondary screening phase. The secondary screen consisted of expression analysis on 26 primary tumors, 19 histologically positive lymph nodes, and 21 benign lymph nodes without cancer.
The only modification was that we doubled the volume of lysis reagent and loaded the column in two steps. This was found to provide better RNA yield and purity, probably because of diluting out the OCT in the tissue sections. For the primary screen, two reverse transcription reactions were done, each with 1, ng of RNA. For the secondary screen, the RNA input for primary tumors and positive nodes was ng per reverse transcription reaction and 20 ng per quantitative PCR reaction, but this was increased to ng per reverse transcription reaction and 80 ng per quantitative PCR reaction for the benign nodes in order to improve sensitivity for detection of low background expression.
Theresa Whiteside, University of Pittsburgh Cancer Institute and SKBR3 cell line served as a universal positive expression control for all the genes in the marker screening process. Probe-based quantitative PCR was done as described previously 26, The sequences of primers and probes purchased from IDT, Coralville, IA for genes evaluated in the secondary screen are listed in Supplementary Table 1. The primer sequences for markers used in the primary screen will be provided upon request. The first derivative of the melting cure was used to determine the product T m as well as to establish the presence of the specific product in each sample.
In general, samples were analyzed in duplicate PCR reactions and the average C t value was used in the expression analysis. However, in the secondary screen triplicate runs were done for each individual benign node and the lowest C t value was used in the calculation of relative expression to obtain the highest value of background expression for the sample. Generation of Prediction Rules.
Six markers that passed the secondary screen were evaluated individually and in combination with other markers. The characteristics used to evaluate markers were sensitivity, specificity, classification, accuracy and the area under the receiver operating characteristic curve. For individual markers, a cutoff value was determined that maximized the classification accuracy proportion of lymph nodes correctly classified. Markers were also combined into pairs for lymph node classification and a linear prediction rule was generated for each pair.
The rule was equivalent to the linear predictor that equalized the fitted probabilities above and below the linear boundary.
That is, points on the boundary line had a predicted probability midway between the numerical scores assigned to positive and negative nodes. Internal Validation of Prediction Rules. Internal validation of prediction rules was conducted by nonparametric bootstrap resampling using Efron and Tibshirani's improved bootstrap method 39 , in which bootstrap samples of lymph nodes are selected from the pool of all positive and negative nodes. The optimism in the original estimates of sensitivity, specificity, and classification accuracy are then calculated as the difference between the bootstrap classification statistic applied to the original data and applied to the bootstrap data.
The average difference over all bootstrap samples is computed and reported as the bias in the values derived from the observed data and then subtracted from the original estimates to produce the bootstrap-validated estimates. The lysis buffer was filtered through a 0. The cartridge is placed in the GeneXpert Supplemental Fig. Probe fluorescence is monitored at each cycle and results are updated on the monitor in real time. This assay was optimized to perform in a rapid, multiplex PCR protocol using our previously published methods for rapid PCR and temperature-controlled primer limiting 34, Our literature and database surveys identified 40 genes for evaluation in the primary tumor marker screen.
Resulting data for the 20 genes with the highest median expression in tumors is shown in Fig. Histograms showing the data from all genes in the primary screen can also be viewed at http: Median relative expression in the primary tumors and benign nodes was calculated for each gene in the primary screen and is reported in Table 2.
In addition, we also calculated the ratio of relative expression between the lowest expressing tumor and the highest expressing benign node, and between the median expression in tumors and the highest expressing benign node. Some genes had no detectable expression in benign nodes and therefore ratios could not be calculated see Table 2.
Primary screen data showing the expression profiles of top 20 genes ranked by median expression in 6 primary head and neck tumors and 10 benign lymph nodes from the patients without cancer. Relative expression in head and neck tumors and benign lymph nodes for the markers analyzed in the primary screen. Similarly, CK18 was excluded based on a combination of low expression ratios and ITGB4 was excluded due to very low median expression in primary tumors.
The relative expression profiles of the markers selected for the secondary screen are shown in Fig. The data shows that all markers are expressed in positive lymph nodes as well as in primary tumors indicating that metastatic tumor cells continue to express these genes. Figure 2 A also indicates the relative expression cutoff values that provide the most accurate classification of histologically positive and benign nodes.
These cutoff values were used to calculate classification characteristics sensitivity, specificity, area under the receiver operating curve, and overall classification accuracy for each marker and the results are presented in Table 3. A, expression profiles of selected markers in primary head and neck tumors T , histologically positive lymph nodes PN , and benign lymph nodes BN from the patients without cancer.
B , two marker prediction on histologically positive nodes red plus sign and benign lymph nodes green circle. Single- or two-marker prediction characteristics on positive and benign lymph nodes in the secondary screen. For all markers, these estimates of classification accuracy are likely to be optimistic because the cutoff value is being generated and tested on the same data set. In an attempt to address this issue, we did an internal marker validation using nonparametric bootstrap analysis to estimate the optimism in our observed classification accuracy.
Marker pairs were evaluated by plotting graphs with expression of one marker on each of the axes and then mathematically calculating a linear cutoff that was midway between the positive and negative lymph node distributions Fig. As with the individual markers, this is likely to be optimistic, and nonparametric bootstrap analysis was therefore done.
Automated Analysis of Lymph Nodes. To show the potential for rapid and automated QRT-PCR analysis of lymph nodes, we analyzed a set of seven benign and seven histologically positive lymph nodes for expression of PVA using the Cepheid GeneXpert instrument.
Pan-keratin immunostaining of these sections, however, revealed extremely small foci of positively staining cells Fig. These micrometastases would likely have been missed on intraoperative frozen section analysis. Thus, PVA expression measured on the automated GeneXpert instrument clearly differentiated positive and benign nodes in this sample set and correctly identified two nodes with micrometastatic disease. In addition, all assays were done in 30 minutes or less, demonstrating the potential for intraoperative analysis of SLNs in head and neck cancer.
PVA expression in benign nodes and head and neck cancer positive lymph nodes as measured on GeneXpert. First, only one or two tissue sections are typically reviewed, leaving the majority of each node unsampled, and second, small foci of tumor cells can be missed.
These limitations are even more pronounced for intraoperative frozen section analysis due to poor tissue architecture and time constraints. Whereas it has been shown that serial sectioning can overcome the issue of sampling error 43, 44 and that the addition of immunohistochemistry staining can improve detection of small tumor foci 28 , the combination of these methods is too time-consuming for intraoperative lymph node analysis. Because cost is also an issue, this detailed analysis approach is limited to examination of fixed tissues in diseases in which SLN biopsy is done, thus reducing the number of lymph nodes to be examined.
Consequently, many patients have to undergo second surgeries to complete lymph node dissection, in cases in which definitive pathologic assessment identifies metastases that were missed on the frozen-section examination. The limited reports on frozen-section sensitivity in SCCHN suggest that a similar scenario is likely to exist if SLN biopsy is done for this tumor type We and others have previously shown that RT-PCR can potentially be more sensitive than routine pathology for analysis of lymph nodes 7, 26, In head and neck cancer specifically, studies on molecular analysis of cervical lymph node metastasis have used a variety of techniques, including PCR amplification to detect p53 mutations 45 , immunohistochemistry staining with or without serial sectioning and histopathologic examination 14—16 , and standard RT-PCR—based analysis of tumor maker gene expression More recently, several groups have used quantitative RT-PCR for detection of cervical lymph node metastases 8, 47 and Nieuwenhuis et al.
This same group also showed the potential for molecular staging of cervical nodes by using tissue obtained via fine-needle aspiration Despite this encouraging work, however, issues remain regarding the most appropriate molecular marker for SCCHN lymph node analysis and the reproducibility and quality control of QRT-PCR in a clinical setting. We address all of these issues in this report. Squamous cell carcinoma antigen SCCA is a member of the ovalbumin family of serine proteinase inhibitors.
The expression of SCCA2 in cancer has been associated with an aggressive phenotype and this gene has been used in several studies for detection of squamous cell carcinoma metastases to lymph nodes The gene encoding PTHrP has been mapped to the short arm of chromosome 12 and is known to contain 6 to 7 exons. Pemphigus vulgaris antigen PVA , also known as desmoglein 3 DSG-3 , is a kDa surface glycoprotein that is the serologic target in the autoimmune skin disease pemphigus vulgaris.
PVA is a member of the desmoglein subfamily of the desmosomal cadherins and the gene encoding this protein has been mapped to the long arm of chromosome 18 and is known to contain 15 exons. Each single-use GeneXpert cartridge consists of multiple reagent reservoirs, a syringe barrel, and a valve mechanism that allows transfer of reagents between reservoirs.
In addition, the cartridges used in this study have a solid-phase matrix for nucleic acid purification and isolation. The detection of occult lymph node disease, and subsequent improved patient staging 28 , could have significant consequences for the treatment of SCCHN.
For example, patients with multiple positive nodes, or extracapsular extension of tumor, are often referred for radiation or chemoradiation therapy, to reduce the high risk of locoregional failure. Resolving this apparent inconsistency relies on the concept that metastases in lymph nodes, independent of approaches employed for their detection, do not guarantee disease recurrence in any individual. Rather, they help to stratify risk. This study is the first to provide level 1 evidence for the application of molecular staging of lymph nodes to individualize prognostic risk in cancer, employing an adequately powered, blinded, prospective multicenter clinical trial design.
Absence of data using this stringent study design has been one critical barrier limiting the translation of molecular diagnostics into patient-centric management paradigms that individualize prediction of risk and therapeutic response. There is an established association between histologic tumor burden, assessed as the number of regional lymph nodes containing cancer cells, and risk of recurrent colorectal cancer [ 2 , 3 , 87 - 93 ]. By extension, the precision of molecular staging also should benefit from appropriate lymph node collections, to most accurately incorporate an assessment of tumor burden into stratification of prognostic risk [ 4 , 5 , 21 ].
metastatic disease. The First International Congress on Molecular Staging of Cancer, Recent Results in Cancer Research. Free Preview. © Small Molecules in Oncology. Series: Recent Results in Cancer Research, Vol. Martens, Uwe (Ed.) Price from $
There is a presumption of an inverse relationship between the quantity of regional lymph nodes harboring molecularly-detected occult metastases and risk of recurrent disease. These considerations support the central importance of adequate regional lymph node collection to optimize molecular [ 4 , 5 , 21 ], as well as histological [ 2 , 3 , 90 , 91 ], detection of metastases to estimate tumor burden and improve risk stratification in colorectal cancer staging.
While the exact number of lymph nodes necessary to optimize patient management has not been precisely clarified, the importance of sufficient lymph node collections to maximize the accuracy of staging and optimize outcomes for patient survival is a mainstay of patient management algorithms in colorectal cancer [ 2 , 3 , 87 - 93 ]. There is an emerging clinical paradigm involving the application of laparoscopy-assisted colectomy to manage patients with colon cancer [ 94 ]. It is noteworthy that this evolution in technique, which strives to reduce surgical morbidity and mortality, restricts collections of lymph nodes for staging [ 94 ].
While these innovations in surgical approaches improve intra-operative management and post-operative recovery, the impact of reduced lymph node sampling on staging accuracy and, ultimately, patient survival has not been precisely quantified. The emergence of molecular staging, offering an unprecedented opportunity to accurately evaluate patient prognosis and predict responses to chemotherapy, highlights the value of defining best practices for lymph node collection that optimize patient outcomes.
Defining the optimum number of nodes for molecular staging, in turn, will provide a rich source of data to inform the evolution of advances in surgical management. It is envisioned that optimizing tissue requirements for molecular staging will drive restricted access surgical techniques to refine lymph node collections, producing integrated algorithms to evolve best management solutions for patients. In addition to the number of lymph nodes harboring cancer cells, there is an apparent association between the quantity of cancer cells in each lymph node, the burden of tumor metastases, and risk of disease recurrence [ 2 , 95 ].
The evolution of molecular staging using qRT-PCR provides a unique paradigm to specifically quantify metastases in tissues, including regional lymph nodes. In that context, qRT-PCR offers unparalleled sensitivity for detection, with the capability of single cell identification in conjunction with analysis of optimum volumes of tissue to avoid sampling errors [ 96 ]. However, that improved sensitivity may translate into identification of occult tumor cells in regional lymph nodes that are below the limit for increased prognostic risk [ 2 ], restricting the specificity of molecular staging [ 44 ].
Future studies will need to identify the quantitative relationship between biomarker levels and prognostic risk, to assess the impact of tumor burden on optimizing prognostic sensitivity and specificity of molecular staging paradigms in cancer [ 44 ]. To date, the most powerful indicator of prognosis and response to adjuvant chemotherapy in colorectal cancer is the identification of cancer cells in lymph nodes by histopathology [ 1 - 6 , 9 , 20 - 23 ]. Despite its central position in all staging paradigms, approaches to detecting lymph node metastases are inadequate.
There is an unmet clinical need for new approaches to more precisely evaluate tumor metastases in regional lymph nodes in colon cancer patients. Recently, a blinded, multicenter, prospective study demonstrated the utility of molecular staging to detect occult tumor metastases in regional lymph nodes to predict risk of disease recurrence [ 44 ]. Occult tumor metastases, defined by molecular staging, was the most powerful independent marker of risk of disease recurrence [ 44 ].
This represents the first level 1 evidence supporting the importance of occult metastases in regional lymph nodes in defining prognostic risk in patients with colon cancer [ 98 ]. These data establish a framework for the application of molecular staging in lymph nodes for individualizing prognostic risk assessment in patients with cancer. While these observations are a beginning, their translation into useful staging tools in cancer will require considerable analyses in the future.
These results will require confirmation in an independent cohort of patients with colorectal cancer, consistent with the emerging learn-confirm paradigm in biomarker translation, wherein integration into patient management algorithms require validation in independent populations [ 99 - ]. Also, the exquisite sensitivity of qRT-PCR [ 96 ], reflecting optimum tissue sampling and ability to discriminate single cells, may reveal occult cancer cells in lymph nodes below the limit for clinical risk [ 2 ], restricting the specificity of molecular staging [ 44 ].
This is exemplified by the identification of occult metastases in the majority of patients, most of whom will remain free of disease [ 2 ]. The next step in the evolution of molecular staging will require a move beyond the simple presence of tumor cells to a standard that integrates the quantity of tumor burden across metastatic sites, including lymph nodes. Molecular staging, specifically the application of qRT-PCR, provides a remarkable platform to quantify occult cancer burden across all regional lymph nodes, and perhaps to more accurately stratify risk and predict therapeutic responses.
Beyond prognosis, there is an established association between metastases in regional lymph node and the efficacy of chemotherapy in patients with colorectal cancer. While adjuvant chemotherapy improves clinical outcomes in stage III patients, its impact on survival in patients that are node-negative by histology remains unclear [ 2 , 3 , 6 , 9 , 20 , 22 , 23 , 38 ].
This heterogeneity of therapeutic benefit in node-negative patients may, in part, reflect the inherent inaccuracy of staging by histopathology [ 4 , 5 , 21 , 24 , 42 - 44 ]. In contrast, molecular staging identified node-negative patients with a prognostic risk profile that closely matched stage III patients, a cohort that derives benefit from adjuvant chemotherapy [ 2 , 3 ].
These observations suggest that node-negative patients who harbor occult metastases detected by molecular staging also could benefit from adjuvant chemotherapy. In the future, studies will examine whether occult lymph node metastases defined by molecular staging predicts chemotherapeutic efficacy. These studies will assess if, in patients with occult metastases in regional lymph nodes identified by molecular staging, those treated with chemotherapy have improved clinical outcomes compared to those who are followed without treatment. Standard algorithms for staging colon cancer patients are largely based on a combination of histological evaluation of primary tumor and regional lymph nodes.
Inadequacies of accepted optical staging algorithms, including tissue sampling and detection limits, can be overcome by molecular staging [ 44 , ]. The molecular detection of occult lymph node metastases is a powerful independent indicator of prognostic risk of colorectal cancer recurrence [ 44 , ]. Early prospective trials strongly suggest that molecular staging through comprehensive lymph node analysis quantifies tumor burden that identifies node-negative patients at increased risk of developing recurrent disease who might be candidates for adjuvant chemotherapy.
Beyond lymph node analyses, evolving genomic platforms provide a rich source of prognostic and predictive information about primary tumors that can enhance staging algorithms optimizing outcomes that drive patient management. Analyses of primary tumors to define gene expression and epigenetic profiles, disease-associated mutations in oncogenes or tumor suppressors, and metabolomic and proteomic signatures that individualize assessments of recurrence risk, responses to adjuvant chemotherapy, and biologically-targeted treatments are enhancing the prognostic and predictive management of cancer patients [ - ].
However, defining the prognostic and predictive character of primary tumors by molecular analyses may be most relevant in the context of whether tumors have metastasized. A primary tumor with a molecular signature suggesting a poor prognosis might represent less risk to the patient if that tumor was completely resected at the time of surgery, before metastases occurred. Thus, emerging technology platforms defining prognosis and prediction for clinical management employing molecular analyses of primary tumors might produce the greatest benefit when applied to patients harboring occult nodal metastases, rather than to those free of metastatic disease.
Here, molecular staging offers a unique opportunity to prioritize complex and expensive molecular analyses of primary tumors to optimize cost-effective patient management [ 44 ]. In the future, trials will examine the applicability of reflexed analytical paradigms in which all histologically node-negative patients undergo molecular staging, to determine whether there is clinically important occult lymph node metastases, followed by further molecular testing of primary tumors only for patients at increased prognostic risk, to identify therapies personalized to the biology of their individual malignancies [ ].
It is important to consider that qRT-PCR is an evolving technical platform that primarily remains the domain of centralized specialty laboratories, and has not yet been broadly distributed to most academic and community medical centers. These realities raise the important question concerning limitations to implementation of molecular staging as a clinical standard central to practice guidelines.
Indeed, the number of esoteric molecular diagnostic tests approved by the FDA each year is growing aggressively, from 72 in to in [ ]. Additionally, the number of home brew molecular diagnostic tests, developed in individual laboratories, was in excess of 1, in [ ]. These considerations suggest that molecular diagnostic tests, including molecular staging, available to clinicians and patients will grow. In the near term, central laboratory performance sites provide the depth of experience and validated technology platforms that align with requirements for FDA regulatory performance and CMS reimbursement.
They will ultimately support the most informative approaches to incorporate molecular staging paradigms into patient-centered algorithms for disease management. SAW is the Samuel M. F inancial and C ompeting I nterest D isclosure. National Center for Biotechnology Information , U. Author manuscript; available in PMC Apr 1. Find articles by Scott A. A uthor A ffiliations: The publisher's final edited version of this article is available at J Surg Oncol. See other articles in PMC that cite the published article. Introduction Clinicopathological staging remains the most important prognostic marker of survival and predictive marker of therapeutic response for most cancer patients.
Staging as a prognostic marker The most significant prognostic marker of colorectal cancer survival is tumor cells in regional lymph nodes [ 1 - 6 , 9 , 20 - 24 ]. Staging as a predictive marker Disease stage in colorectal cancer not only determines patient prognosis, but also predicts which patients will derive benefit from adjuvant therapy.
Molecular Staging Histology remains the most important procedure for staging patients with colon cancer, reflecting the relationship between tumor cells in regional lymph nodes and patient prognosis and prediction [ 1 - 6 , 9 , 20 - 23 ].
Open in a separate window. Identification of occult tumor metastases in lymph nodes employing marker-specific quantitative RT-PCR At the time of colectomy, regional lymph nodes are harvested from tumor-associated mesenteric structures for staging. Prognostic utility of molecular staging to individualize risk assessment Occult metastases identified by molecular staging were an independent marker of risk of recurrent disease. Perspective To date, the most powerful indicator of prognosis and response to adjuvant chemotherapy in colorectal cancer is the identification of cancer cells in lymph nodes by histopathology [ 1 - 6 , 9 , 20 - 23 ].
Summary Standard algorithms for staging colon cancer patients are largely based on a combination of histological evaluation of primary tumor and regional lymph nodes. Footnotes F inancial and C ompeting I nterest D isclosure. CA Cancer J Clin. The staging of colorectal cancer: The prognostic effect of micrometastases in previously staged lymph node negative N0 colorectal carcinoma: Is occult lymph node disease in colorectal cancer patients clinically significant?
A review of the relevant literature. Systemic therapy for colorectal cancer.
N Engl J Med. The annual report to the nation on the status of cancer, , with a special section on colorectal cancer. New directions in the treatment of colorectal cancer: Adjuvant treatment of colorectal cancer. Postoperative radiation therapy for incompletely resected colorectal carcinoma. The spread of rectal cancer and its effect on prognosis. Patterns of recurrence after curative resection of carcinoma of the colon and rectum. Potentially curative surgery of colon cancer: The relationship of survival to staging and grading of colorectal carcinoma: Patterns of recurrence following curative resection of adenocarcinoma of the colon and rectum.
Role of adjuvant therapy in surgically resected colorectal carcinoma. Failure patterns following curative resection of colonic carcinoma. Oxaliplatin, fluorouracil, and leucovorin as adjuvant treatment for colon cancer. Prognostic impact of micrometastases in colon cancer: Adjuvant chemotherapy versus observation in patients with colorectal cancer: Iddings D, Bilchik A. The biologic significance of micrometastatic disease and sentinel lymph node technology on colorectal cancer. Accurate lymph-node detection in colorectal specimens resected for cancer is of prognostic significance.
Surveillance after curative resection o colorectal cancer: Gastrointestinal Endoscopy Clinics of North America. Identification of occult micrometastases in pericolic lymph nodes of Duke's B colorectal cancer patients using monoclonal antibodies against cytokeratin and CC Correlation with long-term survival. Micrometastases and survival in stage II colorectal cancer. Current issues in adjuvant treatment of stage II colon cancer. Targeted agents for adjuvant therapy of colon cancer. Adjuvant chemotherapy for colon and rectal cancer.
Effective surgical adjuvant therapy for high-risk rectal carcinoma. Levamisole and fluorouracil for adjuvant therapy of resected colon carcinoma. The benefit of leucovorin-modulated fluorouracil as postoperative adjuvant therapy for primary colon cancer: Evidence for cure by adjuvant therapy in colon cancer: American Society of Clinical Oncology recommendations on adjuvant chemotherapy for stage II colon cancer.
Adjuvant therapy for stage II colon cancer: Winn R, McClure J. The NCCN clinical practice guidelines in oncology. J Natl Comprehensive Cancer Network. Expert Rev Mol Diagn. Colorectal cancer staging and adjuvant chemotherapy. Association of GUCY2C expression in lymph nodes with time to recurrence and disease-free survival in pN0 colorectal cancer. Ligand-based histochemical localization and capture of cells expressing heat-stable enterotoxin receptors.
Guanylyl cyclase C is a selective marker for metastatic colorectal tumors in human extraintestinal tissues. Escherichia coli heat-stable toxin receptors in human colonic tumors. Age-related differences in receptors for Escherichia coli heat-stable enterotoxin in the small and large intestine of children. The immature rat small intestine exhibits an increased sensitivity and response to Escherichia coli heat-stable enterotoxin.
T84 cell receptor binding and guanyl cyclase activation by Escherichia coli heat-stable toxin. Small and large intestinal guanylate cyclase activity in children: Guanylyl cyclases and signaling by cyclic GMP.