Immunohistochemistry and molecular detection of nodal micrometastases in pancreatic cancer

Pathomorphological features of metastatic lymph nodes as predictors of postoperative prognosis in pancreatic cancer

To investigate the pathological features of metastatic lymph nodes (LN) in pancreatic ductal adenocarcinoma (PDAC) and to determine factors with prognostic implications.Metastatic LN status is a proven significant factor for predicting postoperative prognosis in pancreatic cancer patients. However, the effective prognostic criteria regarding metastatic LNs for such disease remain unknown.We retrospectively reviewed 98 patients with R0/1 resection for PDAC. All metastatic LNs were evaluated for the pathomorphological features of metastasis and analyzed in terms of postoperative outcomes. Various morphological patterns of metastasis were assessed in 440 positive LNs and then classified into 4 groups: common type, direct type (continuously invaded by the main tumor), scatter type (multiple tumor clusters among the normal LN tissues), and isolated tumor cell (ITC).The pathological stage was defined as stage IIA in 10% and IIB in 90% patients. Common-type metastasis was noted in 55% positive LNs of 75% node-positive patients; direct type in 36% LNs of 69% patients; scatter type in 5% LNs of 14% patients; and ITCs in 5% LNs of 18% patients. Significant difference was noted only in recurrence-free survival (RFS) but not in overall survival (OS) in the common-type; only in OS but not in RFS for the scatter type; and neither in RFS nor OS for both direct type and ITC. Multivariate analysis revealed that only LN ratio and curability were independent predictive factors of poor.The tumor distribution patterns in metastatic LNs are the postoperative prognostic factors in pancreatic cancer.

Systematic review of the clinical significance of lymph node micrometastases of pancreatic adenocarcinoma following surgical resection

OBJECTIVES

The aim of this study is to perform a systematic review of the clinical impact of lymph node micrometastasis in pancreatic adenocarcinoma following surgical resection.

METHODS

A systematic review was conducted and published literature were searched using "pancreas or pancreatic" and "cancer or carcinoma or neoplasm", and "micrometastasis or micrometastses" in the PubMed, EMBAE, and Web of Science.

RESULTS

Thirteen publications with 726 patients and 3701 lymph nodes were included in this systematic review. The detection method was immunohistochemical stains or polymerase chain reaction. The pooled proportion of patients with positive lymph node micrometastasis was 43.1% (95% Confidence interval (CI) 0.254-0.628). The pooled proportion of positive lymph node micrometastasis (number of positive lymph node micrometastasis/total number of lymph nodes examined) was 10.8% (95% CI 4.8-22.6). Among the conventional H &E negative patients, the reported 5-year survival rates of the patients without lymph node micrometastases vs. those with lymph node micrometastases in the ranged from 50% to 61% and from 0% to 36%, respectively Patients with lymph node micrometastasis showed poorer survival (Hazard ratio 4.29, 95% CI 1.27-14.41).

CONCLUSIONS

The presence of lymph node micrometastasis is associated with poorer survival. Lymph node micrometastasis is applicable to stratify the risk of recurrence and the need for adjuvant therapy of post-resection patients with pancreatic adenocarcinoma in the conventional H & E lymph node negative patients.

Surgical implication of micrometastasis for pancreatic cancer

OBJECTIVES

The clinical significance of micrometastasis to regional lymph nodes for pancreas cancer is controversial in patients who underwent curative resection.

METHODS

Nine of 42 patients who underwent macroscopically curative resection of pancreatic head cancer were found to have pN(-) by routine examination. Complete serial section examination of the resected specimens was done to detect micrometastasis in these 9 patients.

RESULTS

A total of 16,505 sections were examined by immunohistochemistry or hematoxylin and eosin staining. Micrometastases were identified in 7 (78%) of 9 patients and 17 (3.6%) of 474 lymph nodes. All micrometastases were found in the pancreas head area. However, the frequency of micrometastases around the superior mesenteric artery was 44%. There were no micrometastases to the para-aortic nodes. There was a tendency that the patients with micrometastases showed better survival than those with overt nodal involvement (P = 0.053). Micrometastasis did not provide the poor prognostic factor in patients who underwent optimal regional lymphadenectomy.

CONCLUSIONS

Even in overtly pN(-) pancreatic cancer, micrometastases occur high frequently (78%) and widely, including the nodes around the superior mesenteric artery. These results provide important pathological information when we consider the preoperative, perioperative, and postoperative strategies, even when patients seem to have no nodal involvement by preoperative examinations.

Surgical management of carcinoma of the head of pancreas: extended lymphadenectomy or modified en bloc resection?

Pancreatoduodenectomy for the treatment of periampullary cancer was described over 70 years ago. The technique has evolved in an attempt to improve the dismal prognosis for patients with pancreatic cancers. Radical regional resection has been proposed to decrease the incidence of local recurrence as well as to improve survival. These extended resections have failed to show a significant survival benefit in prospective randomized controlled studies. Furthermore, extended pancreatic resections may be associated with increased morbidity. The concept of modified en bloc resection has been advocated and is soundly based on anatomical and pathological principals. This procedure is a modification of the radical regional resection previously described. It involves resection of the peripancreatic retroperitoneal tissue and lymph nodes en bloc with the head of pancreas, in order to achieve an R0 resection but without the morbidity associated with an extended lymphadenectomy. Conceptually, this procedure may be the most appropriate technique for the management of pancreatic head cancers although the ultimate effect on long-term survival can only be judged after further clinical studies.

Pancreatic cancer--low survival rates

INTRODUCTION

Cancers of the pancreas are identified in 11 800 to 13 500 patients each year in Germany. Epidemiological studies prove smoking and chronic alcohol consumption as causes of about 30% of pancreatic cancers.

METHODS

Selective literature review.

RESULTS

Only patients within TNM stage I and II have after oncologic tumor extirpation a chance for long term survival. Controlled prospective clinical trials demonstrated adjuvant chemotherapy yielding an additional significant survival benefit. The 3- and 5-year-survival after R0-resection and adjuvant chemotherapy are about 30% and below 15% respectively. Using the criteria of observed 5-year-survival less than 2% of all pancreatic cancer patients are alive. After R0-resection the median survival time is between 17 and 28 months, after R1/2-resection between 8 and 22 months.

DISCUSSION

Pancreatic cancer is even today for more than 95% of the patients incurable. Strategies to prevent pancreatic cancer are intended to stop smoking and chronic alcohol consumption and early surgical extirpation of cystic neoplastic lesions. For patients with established pancreatic cancer risk a follow-up protocol is discussed.

New advances in pancreatic surgery

PURPOSE OF REVIEW

New understanding of the dynamic of acute pancreatitis, the clinical impact of local pathology in chronic pancreatitis and cystic neoplastic lesions bearing high potential for malignant transformation has changed the management of pancreatic diseases.

RECENT FINDINGS

In acute pancreatitis, risk factors independently determining outcome in severe acute pancreatitis are early and persistent multiorgan failure, infected necrosis and extended sterile necrosis. The management of severe acute pancreatitis is based on early intensive-care treatment and late surgical debridement. In chronic pancreatitis, recent data from randomized controlled clinical trials have demonstrated duodenum-preserving pancreatic head resection with an inflammatory mass of the head as superior to pylorus-preserving Whipple resection. Cystic neoplasms are local lesions of the pancreas with high malignant potential. Local organ-preserving resection techniques have been applied with low morbidity and mortality, replacing a Whipple-type resection. Resection of pancreatic cancer is ineffective to cure patients. After an R0-resection, a significant survival benefit has been achieved when adjuvant chemotherapy has additionally been applied.

SUMMARY

New knowledge about the nature of inflammatory diseases, cystic neoplastic lesions and malignant pancreatic tumours has changed the indication for surgical treatment and the application of organ-preserving surgical techniques.

Resection of the mesopancreas (RMP): a new surgical classification of a known anatomical space

Background

Prognosis after surgical therapy for pancreatic cancer is poor and has been attributed to early lymph node involvement as well as to a strong tendency of cancer cells to infiltrate into the retropancreatic tissue and to spread along the peripancreatic neural plexuses. The objective of our study was to classify the anatomical-surgical layer of the mesopancreas and to describe the surgical principles relevant for resection of the mesopancreas (RMP). Immunohistochemical investigation of the mesopancreatic-perineural lymphogenic structures was carried out with the purpose of identifying possible routes of metastatic spread.

Methods

Resection of the mesopancreas (RMP) was performed in fresh corpses. Pancreas and mesopancreas were separated from each other and the mesopancreas was immunohistochemically investigated.

Results

The mesopancreas strains itself dorsally of the mesenteric vessels as a whitish-firm, fatty tissue-like layer. Macroscopically, in the dissected en-bloc specimens of pancreas and mesopancreas nerve plexuses were found running from the dorsal site of the pancreatic head to the mesopancreas to establish a perineural plane. Immunohistochemical examinations revealed the lymphatic vessels localized in direct vicinity of the neuronal plexuses between pancreas and mesopancreas.

Conclusion

The mesopancreas as a perineural lymphatic layer located dorsally to the pancreas and reaching beyond the mesenteric vessels has not been classified in the anatomical or surgical literature before. The aim to ensure the greatest possible distance from the retropancreatic lymphatic tissue which drains the carcinomatous focus can be achieved in patients with pancreatic cancer only by complete resection of the mesopancreas (RMP).

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.

Detection of tumor cell dissemination in pancreatic ductal carcinoma patients by CK 20 RT-PCR indicates poor survival

PURPOSE

This prospective study evaluates the diagnostic potential of Cytokeratin 20 (CK 20) RT-PCR for the detection of disseminated tumor cells in bone marrow and blood of a large cohort of patients with ductal adenocarcinoma of the pancreas and the prognostic value on overall survival prediction.

METHODS

Between 1994 and 2003, 172 patients (83 male, 89 female; 13-82 years) with pancreatic ductal adenocarcinoma underwent surgery. Bone marrow samples and venous blood were taken preoperatively and analyzed for disseminated tumor cells by nested CK 20 RT-PCR.

RESULTS

Disseminated tumor cells were detected in 81 (47.1%) of the 172 patients in the bone marrow and/or the venous blood. Overall, in 45 of the 135 (33.3%) bone marrow samples and in 52 of the 154 (33.8%) blood samples, CK 20 positive cells were detected. Detection rates increased with the UICC-tumor stage. According to Kaplan-Meier, univariate survival analysis of all 172 patients (n = 78 R0-; n = 18 R1- and n = 5 R2-resected; n = 71 palliative surgery) showed a statistically significant relationship of overall survival to radicality of the operation (P < 0.0001), the UICC-stage of the tumors (P = 0.0011) and the detection of disseminated tumor cells in bone marrow and/or venous blood (P = 0.05). Patients with well- and moderately- differentiated tumors (G1 and G2) had a significantly longer survival (P = 0.045) than patients suffering from poorly differentiated tumors (G3). A positive CK 20 status in the bone marrow and/or blood within the group of patients with G1 and G2 tumors had a significantly negative prognostic impact on their survival (P = 0.046).

CONCLUSIONS

Disseminated tumor cells can be detected in patients with pancreatic ductal adenocarcinoma by CK 20 RT-PCR. Detection rates are stage dependent, and survival analysis demonstrated statistically relevant data. From a clinical point of view, this finding is especially noteworthy for the group of well- and moderately-differentiated tumors.

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.

The characteristics of disseminated tumor cells in pancreatic cancer: a black box needs to be explored

Despite recent advances in early diagnosis and surgical treatment, the clinical outcome of patients with pancreatic cancer has not been improved markedly. One of the reasons for the dismal outcome is early dissemination of tumor cells. Sensitive immunohistocytochemical and nucleic acid-based assays have detected disseminated tumor cells in the lymph nodes, bone marrow, peritoneal cavity or peripheral blood. Formation of the metastatic disease depends on the nature of the disseminated tumor cells. Standardization of protocols is mandatory to detect occult tumor cells in clinical practice. We present an overview of recent studies on the incidence, prognostic values and some characteristics of occult tumor cells disseminated in the secondary sites of patients with pancreatic cancer.

Cytokeratin is a superior marker for detection of micrometastatic biliary tract carcinoma

BACKGROUND

The incidence of lymph node micrometastases in patients with biliary tract carcinoma is unknown. We evaluated the utility of three antibodies for immunohistochemical (IHC) detection of micrometastatic disease in patients with gallbladder and bile duct carcinoma.

MATERIALS AND METHODS

Surgical specimens from 35 patients with biliary tract carcinoma were evaluated. Histologically involved tissues were stained with the following antibodies using standard IHC techniques: cytokeratin (AE1:AE3), CEA (carcinoembryonic antigen), and EMA (epithelial membrane antigen). The antibodies with the greatest degree of positive staining were then used to evaluate the lymph nodes of patients with histologically negative lymph nodes. Micrometastatic disease was defined as clustered atypical cells <2 mm in size detected only with the use of IHC.

RESULTS

All of the primary tumors and histologically positive lymph nodes demonstrated staining with cytokeratin and CEA antibodies, whereas only 83% were positive for EMA. Therefore, cytokeratin and CEA antibodies were used to evaluate histologically negative lymph nodes. Anti-cytokeratin immunostaining detected micrometastatic disease in two patients. Staining with anti-CEA was negative in all specimens. Overall, two of 15 patients with histologically node negative biliary tract carcinoma had occult micrometastases.

CONCLUSION

Cytokeratin immunostaining enables detection of micrometastases in histologically negative lymph nodes in patients with biliary tract carcinoma. Prospective protocols incorporating cytokeratin staining of the lymph nodes may help determine the incidence and clinical significance of occult micrometastatic disease in these patients.

Current standards of surgery for pancreatic cancer

Background

Pancreatic cancer carries a dismal prognosis but there has been a vast increase in evidence on its management in the past decade.

Methods

An electronic and manual search was performed for articles on the surgical treatment of pancreatic cancer published in the past 10 years.

Results

Six major areas of advancement were identified. Groups at high risk of developing pancreatic cancer, notably those with chronic pancreatitis and hereditary pancreatitis, have been defined, raising the need for secondary screening. Methods of staging pancreatic cancer for resection have greatly improved but accuracy is still only 85–90 per cent. Pylorus-preserving partial pancreatoduodenectomy without extended lymphadenectomy is the simplest procedure; it does not compromise long-term survival. Adjuvant chemotherapy significantly improves long-term survival. Patients who are free from major co-morbidity have better palliation by surgery (with a double bypass) than by endoscopy. High-volume centres improve the results of surgery for all outcome measures including long-term survival.

Conclusion

The surgical management of pancreatic cancer has undergone a significant change in the past decade. It has moved away from no active treatment. The standard of care can now be defined as potentially curative resection in a specialist centre followed by adjuvant systemic chemotherapy.

Prognostic implications of routine, immunohistochemical, and molecular staging in resectable pancreatic adenocarcinoma

Cure for ductal adenocarcinoma of the pancreas is restricted to resectable tumors, but survival after surgery is still poor. Despite apparently curative resection, these cancers rapidly recur. Thus, the present pathologic examination should be enriched by sensitive methods to detect minimal residual disease. In a prospective setting we studied the frequency of minimal residual disease after curative resection by routine histopathology, immunohistology, and polymerase chain reaction (PCR) for mutated K-ras. Furthermore, the prognostic implication of detecting of MRD was determined. Prospectively, tumor tissue and corresponding paraaortic lymph nodes were obtained from 78 patients, who underwent surgery for pancreatic head tumors between 1999 and 2001. Sixty-nine of 78 cases were diagnosed for ductal adenocarcinoma (study group), whereas nine cases were diagnosed for benign pancreatic tumors (control group). Paraaortic lymph nodes were examined in step sections by routine histopathology (hematoxylin and eosin) and immunohistology using a pan-cytokeratin antibody. DNA of the primary tumor and corresponding paraaortic lymph nodes were analyzed by PCR-based assays with respect to mutated K-ras in codon 12. The recurrence-free survival and overall survival were correlated with the results of the latter methods. In 3 of 69 patients tumor cells were detected in paraaortic lymph nodes by routine histopathology and in 5 of 69 patients by immunohistology. K-ras mutations were detected in 42 of 69 ductal adenocarcinomas (61%), whereas 12 (17%) were positive in paraaortic lymph nodes. All of the latter patients had recurrence after surgery and a significant poorer survival than those without mutated K-ras. Furthermore, paraaortic lymph nodes diagnosed for K-ras mutation were independent prognostic markers in multivariate analysis. In the control group K-ras mutations were detected in one adenoma of Vater's papilla but not in paraaortic lymph nodes. Tumor cell DNA can be detected more sensitively by the described PCR method than with hematoxylin and eosin or immunohistologic staining, leading to a higher sensitivity for detection of micrometastases. The described PCR method clearly determines subgroups of patients after curative resection with early recurrence and poor survival and could therefore enrich the pathologic examination.

Detection and prognostic impact of disseminated tumor cells in pancreatic carcinoma

BACKGROUND/AIMS

Metastatic disease determines the prognosis of patients with pancreatic cancer. Current routine staging methods often underestimate the tumor stage because they do not include the search for disseminated tumor cells that spread early in different compartments of the body. Immunohistochemical and molecular methods developed recently are able to detect these cells in multiple compartments of the body.

METHODS

The current status of the detection and the prognostic impact of disseminated tumor cells detected in lymph nodes, bone marrow, blood and peritoneal lavage of patients with pancreatic carcinoma are reviewed.

RESULTS

Disseminated tumor cells can be detected in different compartments of the body even in early tumor stages and when a resection of the primary tumor in curative intention was performed. Furthermore, the detection of these cells has importance for the prognosis and therefore will have therapeutic implications. Standardization of the methods is a prerequisite for further studies.

CONCLUSION

The detection of disseminated tumor cells should be included into studies to reveal that this increased staging has an prognostic impact and can be useful for therapeutic decisions in patients with pancreatic carcinoma.

Molecular assessment of lymph nodes in patients with resected stage I non-small cell lung cancer: preliminary results of a prospective study

OBJECTIVES

Routine histologic examination of resected lymph nodes in patients with stage I non-small cell lung cancer may underestimate the incidence of advanced disease. The presence of occult lymph node metastases may predict a higher risk of recurrence after intended curative resection. The purpose of this study was to determine the prognostic significance of TP53 and K-ras mutations in histologically determined negative lymph nodes from patients with stage I non-small cell lung cancer who underwent intended curative surgical resection.

METHODS

Between July 1995 and March 1998, clinical data and tissue samples of primary tumors and lymph nodes were collected in a prospective fashion from 102 patients undergoing resection for non-small cell lung cancer (stage I, n = 55; stage II, n = 32; stage IIIA, n = 15). TP53 and K-ras mutations were detected by direct sequencing. If molecular alterations were found in the primary tumor, the corresponding lymph nodes were examined for these same TP53 (by oligonucleotide hybridization) and K-ras (by allele-specific ligation) mutations.

RESULTS

TP53 mutations were found in 47 of 94 primary tumors (50%), and K-ras mutations were present in 26 of 55 adenocarcinomas (47%). A total of 134 lymph nodes from 32 patients with stage I disease were analyzed. In 9 cases (28%) the same TP53 or K-ras mutations were found in tumor and lymph node specimens, suggesting occult metastasis. On the basis of nodal location, 7 patients had their disease upstaged by a single stage and 2 patients by two stages. All 28 patients with stage II or III disease had pathologically determined positive nodes that were confirmed as positive by molecular analysis. Standard histopathologic assessment of regional lymph nodes failed to detect metastases at levels below 0.9% tumor-specific mutant TP53 clones per node. No statistically significant difference in disease-specific or overall survival was observed between patients with stage I disease with and without molecular lymph node metastases.

CONCLUSIONS

Occult lymph node metastases are present in a significant percentage of patients with stage I non-small cell lung cancer. These data suggest that molecular analysis allows a more accurate assessment of staging. However, larger studies are needed to determine the clinical role of molecular staging.