Technical limitations of lymph node mapping in pancreatic cancer

Use of indocyanine green near-infrared lymphography to detect sentinel lymph nodes in a dog with a malignant insulinoma: a case report

Malignant insulinoma is the most common type of neuroendocrine tumor found in the pancreas of dogs. Canine insulinoma displays malignant behavior with a high rate of metastasis. The most common sites of metastases are the draining lymph nodes, which are also the primary location sites for the recurrence of functional disease. However, identifying metastatic nodes can often be complicated, as the pancreas is drained by numerous lymphatic centers, and clinical enlargement or structural changes may not always be present in metastatic nodes. Additionally, unaltered nodes are frequently small (a few millimeters) and can be hard to distinguish from the surrounding tissues. Therefore, lymphadenectomy is generally recommended for affected dogs. Unlike in human medicine, there are currently no established strategies for lymph node resection in dogs with malignant insulinoma. This report presents a technique for identifying and removing sentinel nodes using indocyanine green and near-infrared lymphography (NIRFL) during surgery. A total of six sentinel nodes were detected and resected with this method. This technique could provide a more structured approach for lymph node resection in affected dogs and potentially in humans in the future. However, its therapeutic benefits must be evaluated in a larger cohort of cases.

Optimal Lymphadenectomy of the Mesopancreas Based on Fluorescence Imaging During Pancreaticoduodenectomy

BACKGROUND

Excision of the mesopancreas with lymphadenectomy is an important component of pancreatoduodenectomy. However, the optimal extent of lymphadenectomy remains unclear. Furthermore, accurate description of the mesopancreatic lymphatic pathways is difficult, probably because of the complex anatomy. Intestinal derotation simplifies the anatomy and facilitates both examination of lymphatic flow and the surgical procedure. The aim of this study was to evaluate lymphatic flow in the mesopancreas using indocyanine green fluorescence imaging with an intestinal derotation technique, and to clarify the optimal extent of mesopancreas excision and lymphadenectomy in pancreatoduodenectomy.

METHODS

Indocyanine green solution (2.5 × 10^-3 mg) was injected into the pancreatic head parenchyma. After intestinal derotation, the spread of indocyanine green was observed using near-infrared imaging.

RESULTS

Participants comprised 10 patients who underwent pancreatoduodenectomy for periampullary neoplasms. With indocyanine green fluorescence imaging, 9 of the 10 patients showed lymphatic flow from the pancreatic head to the superior mesenteric artery via the inferior pancreaticoduodenal artery and first jejunal artery (but not via the second and more distant arteries), with eventual drainage into the paraaortic region.

CONCLUSIONS

Lymphatic pathways from the pancreatic head were connected to the superior mesenteric artery via the inferior pancreaticoduodenal artery and first jejunal artery. Excision of the mesopancreas with the inferior pancreaticoduodenal artery and first jejunal artery while preserving the second or more distant arteries appears optimal in pancreatoduodenectomy for periampullary malignancies.

Defining a minimum number of examined lymph nodes improves the prognostic value of lymphadenectomy in pancreas ductal adenocarcinoma

BACKGROUND

Lymph node (LN) metastasis is associated with decreased survival following resection for pancreatic ductal adenocarcinoma (PDAC). In N0 disease, increasing total evaluated LN (ELN) correlates with improved outcomes suggesting patients may be understaged when LNs are undersampled. We aim to assess the optimal number of examined lymph nodes (ELN) following pancreatectomy.

METHODS

Data from 1837 patients undergoing surgery were prospectively collected. The binomial probability law was utilized to analyze the minimum number of examined LNs (minELN) and accurately characterize each histopathologic stage. LN ratio (LNR) was compared to American Joint Committee on Cancer (AJCC) guidelines.

RESULTS

As ELN total increased, the likelihood of finding node positive disease increased. An evaluation based upon the binomial probability law suggested an optimal minELN of 12 for accurate AJCC N staging. As the number of ELNs increased, the discriminatory capacity of alternative strategies to characterize LN disease exceeded that offered by AJCC N stage.

CONCLUSION

This is the first study dedicated to optimizing histopathologic staging in PDAC using models of minELN informed by the binomial probability law. This study highlights two separate cutoffs for ELNs depending upon prognostic goal and validates that 12 LNs are adequate to determine AJCC N stage for the majority of patients.

The accuracy of sentinel node biopsy by 99mTc-sodium phytate in patients with pancreatic cancer

Backgrounds/Aims

Pancreaticoduodenectomy is the only potentially curative treatment for pancreatic cancer. The identification of the first nodal drainage site (sentinel node) may improve the detection of metastatic nodes and can contribute to a less invasive surgery. We aimed to determine the accuracy of sentinel node mapping in patients with pancreatic cancer using intraoperative radiotracer injection technique.

Methods

At surgical exposure, peritumoral injection of 0.4-0.5 mci/0.5 ml of 99mTc- sodium phytate was performed. After tumor resection, sentinel nodes were investigated in the most common areas using a hand-held gamma probe. Any lymph node with in vivo count twice the background was considered as sentinel node, thus, it was removed and sent for pathological assessment. Then a standard lymph node dissection was performed for all patients.

Results

Fourteen patients with cancer in the head of the pancreas were included in this study. Overall, 180 lymph nodes were harvested with a mean of 11.6±4.7 lymph nodes per patient. In eight patients, at least one sentinel node could be identified (detection rate about 64%). False negative rate of the study was 3/5 (60%).

Conclusions

Our study revealed insufficient diagnostic accuracy and high false negative rate for sentinel lymph node mapping with 99mTc- sodium phytate in pancreatic cancer.

Trends in the Number of Lymph Nodes Evaluated Among Patients with Pancreatic Neuroendocrine Tumors in the United States: A Multi-Institutional and National Database Analysis

BACKGROUND

The role of routine lymphadenectomy in the surgical treatment of pancreatic neuroendocrine tumors (pNET) remains poorly defined. The objective of the current study was to investigate trends in the number of lymph nodes (LN) evaluated for pNET treatment at a nationwide level.

METHODS

Patients undergoing surgery for pNET between 2000 and 2016 were identified in the U.S. Neuroendocrine Tumor Study Group (US-NETSG) database as well as the Surveillance, Epidemiology, and End Results (SEER) database. The number of LNs examined was evaluated over time.

RESULTS

The median number of evaluated LNs increased roughly fourfold over the study period (US-NETSG, 2000: 3 LNs vs. 2016: 13 LNs; SEER, 2000: 3 LNs vs. 2016: 11 LNs, both p < 0.001). While no difference in 5-year OS and RFS was noted among patients who had 1-3 lymph node metastases (LNM) vs. ≥ 4 LNM between 2000-2007 (OS 73.5% vs. 69.9%, p = 0.12; RFS: 64.9% vs. 40.1%, p = 0.39), patients who underwent resection and LN evaluation during the period 2008-2016 had an incrementally worse survival if the patient had node negative disease, 1-3 LNM and ≥ 4 LNM (OS 86.8% vs. 82.7% vs. 74.9%, p < 0.001; RFS: 86.3% vs. 64.7% vs. 50.4%, p < 0.001). On multivariable analysis, a more recent year of diagnosis, pancreatic head tumor location, and tumor size > 2 cm were associated with 12 or more LNs evaluated in both US-NETSG and SEER databases.

CONCLUSION

The number of LNs examined nearly quadrupled over the last decade. The increased number of LNs examined suggested a growing adoption of the AJCC staging manual recommendations regarding LN evaluation in the treatment of pNET.

Lymphadenectomy in pancreatic neuroendocrine neoplasms: Why are we still debating?

Pancreatic Neuroendocrine Neoplasms (PNEN) are rare tumours exhibiting very heterogeneous behaviour. For these reasons, studies with high level of evidence are lacking. Whether lymphadenectomy should be performed for PNEN is a matter of debate. In this review, we perform a critical analysis of the available literature regarding the clinical significance of lymphnode metastases, the importance of lymphadenectomy, and the implications on disease-specific survival.

Application of Deuteporfin in the Metastatic Lymph Node Mapping of Pancreatic Cancer: An in vivo Study

For most cancer patients, the presence of metastatic lymph nodes usually indicates regional recurrence and poor prognosis. Therefore, lymph node mapping is a requisite for disease staging, prognosis prediction and decision making in the treatment of cancer. Deuteporfin, a second-generation photosensitizer, has a maximum excitation wavelength that can reach the near infrared (NIR) region (650-700 nm). We aimed to take advantage of these aspects of deuteporfin and use it as a fluorescent probe for metastatic lymph node mapping in vivo using NIR fluorescent imaging. In our study, we further investigated whether a photosensitizer could be used as a tracer for metastatic lymph node mapping of pancreatic cancer based on previous reports. Compared to normal tissues, tumor tissues including primary tumors and metastatic lymph nodes had a higher uptake ability of deuteporfin (P < 0.05). Our research confirmed this targeting property of deuteporfin using in vivo fluorescent imaging. Consistent with observations from in vivo imaging experiments, frozen sections of metastatic lymph nodes intuitively displayed significantly higher and wider distributions of deuteporfin than normal sections.

MicroRNA Expression in a Readily Accessible Common Hepatic Artery Lymph Node Predicts Time to Pancreatic Cancer Recurrence Postresection

Lymph node involvement in pancreatic adenocarcinoma (PAC) predicts postresection survival, but early lymph node metastasis detection is not easily accomplished. We assessed a panel of microRNAs (miRNAs) in a common hepatic artery lymph node (station 8) that is readily accessible during pancreatoduodenectomy (PD) to determine if increased miRNA levels correlate with postresection recurrence. Station 8 lymph nodes overlying the common hepatic artery collected during PD were assayed for miRNA-10b, miRNA-30c, miRNA-21, and miRNA-155 and cytokeratin-19 (CK19), an epithelial cell marker, using quantitative PCR. Expression was correlated with disease recurrence, recurrence-free survival (RFS), and overall survival (OS). Station 8 lymph nodes from 37 patients (30 periampullary carcinomas (PCs), 2 chronic pancreatitis, 5 other cancers) exhibited increased miRNA-10b levels in 14/30 PCs, and in 10 of these 14 patients, cancer recurred during the study period (2012-2015). High miRNA-10b was also associated with shorter RFS (42.5 vs. 92.4 weeks, p < 0.05) but not OS, whereas miRNA-30c, miRNA-21, and miRNA-155 levels and CK19 mRNA levels in station 8 nodes were variable and did not correlate with RFS or OS. We conclude that elevated miRNA-10b levels in station 8 lymph nodes could be utilized to assess risk for early disease progression in patients with periampullary tumors.

Experimental Study of Magnetic Multi-Walled Carbon Nanotube-Doxorubicin Conjugate in a Lymph Node Metastatic Model of Breast Cancer

BACKGROUND The lymphatic system plays a significant role in the defense of a subject against breast cancer and is one of the major pathways for the metastasis of breast cancer. To improve the prognosis, many means, including surgery, radiotherapy, and chemotherapy, have been used. However, the combination of all these modalities has limited efficacy. Lymph nodes, therefore, have become an exceptionally potential target organ in cancer chemotherapy. MATERIAL AND METHODS A lymph node metastatic model of breast cancer was established in BALB/c mice. Magnetic multi-walled carbon nanotube carrier with good adsorption and lymph node-targeting capacity was prepared and conjugated with doxorubicin to make the magnetic multi-walled carbon nanotube-doxorubicin suspension. Dispersions of doxorubicin, magnetic multi-walled carbon nanotube-doxorubicin, and magnetic multi-walled carbon nanotube were injected into lymph node metastatic mice to compare their inhibitory effects on tumor cells in vivo. Inhibition of these dispersions on EMT-6 breast cancer cells was detected via MTT assay in vitro. RESULTS Although no significant difference was found between the effects of doxorubicin and magnetic multi-walled carbon nanotube-doxorubicin with the same concentration of doxorubicin on EMT-6 breast cancer cells in vitro, in terms of sizes of metastatic lymph nodes and xenograft tumors, apoptosis in metastatic lymph nodes, and adverse reactions, the magnetic multi-walled carbon nanotube-doxorubicin group differed significantly from the other groups. CONCLUSIONS The magnetic multi-walled carbon nanotube-doxorubicin clearly played an inhibitory role in lymph node metastases to EMT-6 breast cancer cells.

The lymphatic system and pancreatic cancer

This review summarizes current knowledge of the biology, pathology and clinical understanding of lymphatic invasion and metastasis in pancreatic cancer. We discuss the clinical and biological consequences of lymphatic invasion and metastasis, including paraneoplastic effects on immune responses and consider the possible benefit of therapies to treat tumors that are localized to lymphatics. A review of current techniques and methods to study interactions between tumors and lymphatics is presented.

Initial experience in sentinel lymph node detection in pancreatic cancer

BACKGROUND

The local recurrence of pancreatic cancer is around 30% when complete resection can be achieved. Extended lymphatic resections may improve survival, but increases severe morbidity. As accurate patient selection should be mandatory, a new method is presented for pancreatic sentinel lymph node (SLN) detection with lymphoscintigraphy and gamma probe.

MATERIALS AND METHODS

Seven patients with cT2N0M0 pancreatic head cancer were enrolled between 2009 and 2012 in this prospective study. One day prior to surgery, preoperative lymphoscintigraphy with echoendoscopic intratumoural administration of Tc(99m)-labelled nanocolloid was performed, with planar and SPECT-CT images obtained 2h later. Gamma probe detection of SLN was also carried out during surgery.

RESULTS

Radiotracer administration was feasible in all patients. Scintigraphy images showed inter-aortocaval lymph nodes in 2 patients, hepatoduodenal ligament lymph nodes in 1, intravascular injection in 3, intestinal transit in 5, and main pancreatic duct visualisation in 1. Surgical resection could only be achieved in 4 patients owing to locally advanced disease. Intraoperative SLN detection was accomplished in 2 patients, both with negative results. Only in one patient could SLN be confirmed as truly negative by final histopathological analysis.

CONCLUSIONS

This new method of pancreatic SLN detection is technically feasible, but challenging. Our preliminary results with 7 patients are not sufficient for clinical validation.

Sentinel lymph node mapping in tumors of the pancreatic body: preliminary report

Aim of the study

Actual lymphatic drainage of pancreatic body neoplasms and the proper extent of lymphadenectomy remain unknown. The aim of the study was to define the exact lymphatic draining pattern using the dye mapping method.

Material and methods

The study enrolled patients who were operated on for tumor of the pancreatic body in the Department of General and Transplant Surgery of the Medical University of Lodz during 2010, with injection of 1 ml of blue dye (Patent Blue, Guerbet) in the centre of the neoplasm and sentinel node identification. Radical surgical management included distal pancreatectomy, whereas gastrojejunal or triple bypass anastomoses were performed in irresectable cases.

Results

The study group consisted of 13 patients with locally advanced tumors of the pancreatic body (T3 and T4, mean tumor size 4.9 cm). Lymphatic mapping was able to identify sentinel nodes in 5 of 13 cases (38.46%). A sentinel node was found in station 11p (3 cases) and 9 (1 case). Skip metastasis to the left gastric artery node (group 7) was noted. All identified sentinel nodes were metastatic; tumor deposits were confirmed in non-sentinel nodes as well.

Conclusions

In advanced pancreatic body tumors feasibility of sentinel node navigation is considerably restricted. Further studies in smaller tumors using optimized newer markers may define the exact lymphatic draining pattern.

Identification of the lymphatic drainage pathways from the pancreatic head guided by indocyanine green fluorescence imaging during pancreaticoduodenectomy

AIMS

We identified the lymphatic drainage pathways from the pancreatic head guided by indocyanine green (ICG) fluorescence imaging to analyze optimal lymphadectomy for pancreatic cancer.

METHODS

The lymphatic pathways in 20 patients undergoing pancreaticoduodenectomy were analyzed. We injected ICG into the parenchyma in the anterior (n = 10) or posterior surface (n = 10) of the pancreas head and observed the intraoperative lymphatic flows by ICG fluorescence imaging.

RESULTS

The seven main lymphatic drainage pathways were identified: (1) along the anterior or posterior pancreaticoduodenal arcade, (2) running obliquely down behind the superior mesenteric vein (SMV), (3) reaching the left side of the superior mesenteric artery (SMA), (4) running longitudinally upward between the SMV and SMA, (5) along the middle colic artery toward the transverse colon, (6) reaching the paraaortic (PA) region, and (7) reaching the hepatoduodenal ligament. The lymphatic pathway reaching the left side of the SMA was observed in 4 patients (20%), while that reaching the PA region in 17 patients (85%). The mean time to reach around the SMA was longer than that to reach the PA region.

CONCLUSIONS

We found that several lymphatic drainage routes were observed from the pancreatic head, suggesting that a lymphadectomy around the SMA might have a similar oncological impact as that of the PA region.

Proposing the lymphatic target volume for elective radiation therapy for pancreatic cancer: a pooled analysis of clinical evidence

Background

Radiation therapy is an important cancer treatment modality in both adjuvant and definitive setting, however, the use of radiation therapy for elective treatment of regional lymph nodes is controversial for pancreatic cancer. No consensus on proper selection and delineation of subclinical lymph nodal areas in adjuvant or definitive radiation therapy has been suggested either conclusively or proposed for further investigation. This analysis aims to study the pattern of lymph node metastasis through a pooled analysis of published results after radical tumor and lymph nodal resection with histological study in pancreatic cancer.

Methods

Literature search using electronic databases including MEDLINE, EMBASE, and CANCERLIT from January 1970 to June 2009 was performed, supplemented by review of references. Eighteen original researches and a total of 5954 pancreatic cancer patients underwent radical surgical resection were included in this analysis. The probability of metastasis in regional lymph nodal stations (using Japan Pancreas Society [JPS] Classification) was calculated and analyzed based on the location and other characteristics of the primary disease.

Results

Commonly involved nodal regions in patients with pancreatic head tumor include lymph nodes around the common hepatic artery (Group 8, 9.79%), posterior pancreaticoduodenal lymph nodes (Group 13, 32.31%), lymph nodes around the superior mesenteric artery (Group 14, 15.85%), paraaortic lymph nodes (Group 16, 10.92%), and anterior pancreaticoduodenal lymph nodes (Group 17, 19.78%); The probability of metastasis in other lymph nodal regions were <9%.

Commonly involved nodal regions in patients with pancreatic body/tail tumor include lymph nodes around the common hepatic artery (Group 8, 15.07%), lymph nodes around the celiac trunk (Group 9, 9.59%), lymph nodes along the splenic artery (Group 11, 35.62%), lymph nodes around the superior mesenteric artery (Group 14, 9.59%), paraaortic lymph nodes (Group 16, 16.44%), and inferior body lymph nodes (Group 18, 24.66%). The probability of metastasis in other lymph nodal regions were <9%.

Conclusions

Pancreatic cancer has a high propensity of regional lymphatic metastases; however, clear patterns including the site and probability of metastasis can be identified and used as a guide of treatment in patients with resectable pancreatic cancer. Further clinical investigation is needed to study the efficacy of elective treatment to CTV defined based on these patterns using high-dose conformal or intensity-modulated radiation therapy.

Feasibility and reliability of pancreatic cancer staging using fiberoptic confocal fluorescence microscopy in rats

BACKGROUND & AIMS

Surgical management of pancreatic cancer depends on tumor resectability and staging. This study evaluated a new in vivo technique, fiberoptic confocal fluorescence microscopy (FCFM), for detection and staging of pancreatic tumors in rats.

METHODS

FCFM was used with a protease-activated fluorescent marker (ProSense; VisEn Medical Inc, Woburn, MA) for in vivo imaging of solid organs (1.8-microm resolution) in a rat model of pancreatic ductal adenocarcinoma. A preliminary study described the FCFM rendering of normal and pathologic tissues. Subsequently, 2 double-blind studies compared FCFM to standard histology in (1) detection of tumors in rat models of cancer and controls and (2) detection of nodal involvement (splenic, celiac, mesenteric, and colic) 4, 5, and 6 weeks after tumor induction vs controls.

RESULTS

Tumor cells displayed a fluorescent ductal pattern compared with non-fluorescent normal pancreas or normal follicular pattern of lymph nodes (LNs). FCFM detected all the pancreatic tumors (1.7-mm mean diameter) and identified 23 LNs that contained metastases of 99 LNs examined. Standard histologic analyses resulted in 1 false-negative result in tumor detection and 2 false negatives in LN detection, whereas FCFM produced no false-negative results. Additional serial sectioning confirmed all tumors and 16 metastatic LNs; FCFM had a negative predictive value of 100% and a positive predictive value of 69.6%.

CONCLUSIONS

Real-time "virtual biopsy" using FCFM detects tumors and LN metastases with 100% sensitivity and 92.2% specificity in rats, making it a reliable technique for detection and staging of pancreatic cancer.

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A. Sauvanet Several factors argue for extended lymphadenectomy in surgery for pancreatic adenocarcinoma: 1) lymph node extension is an adverse prognostic factor; 2) some tumor recurrences are only loco-regional suggesting that initial resection was insufficient; 3) some retrospective studies suggest that extension of lymphadenectomy improves post-resection survival. Extended lymphadenectomy, including circumferential dissection of both the celiac axis and the superior mesenteric artery and resection of para-aortic nodes, was evaluated by 4 randomized trials; globally there was no survival benefit. Extended lymphadenectomy increases, at least transiently, the risk of post-operative diarrhea. Its influence on the rate of loco-regional recurrences has not been evaluated. However, this technique should not be definitively and globally precluded since a more radical resection was associated with a trend toward better long-term survival in the trial with the largest number of patients.

[Not Available]

A. Sauvanet Several factors argue for extended lymphadenectomy in surgery for pancreatic adenocarcinoma: 1) lymph node extension is an adverse prognostic factor; 2) some tumor recurrences are only loco-regional suggesting that initial resection was insufficient; 3) some retrospective studies suggest that extension of lymphadenectomy improves post-resection survival. Extended lymphadenectomy, including circumferential dissection of both the celiac axis and the superior mesenteric artery and resection of para-aortic nodes, was evaluated by 4 randomized trials; globally there was no survival benefit. Extended lymphadenectomy increases, at least transiently, the risk of post-operative diarrhea. Its influence on the rate of loco-regional recurrences has not been evaluated. However, this technique should not be definitively and globally precluded since a more radical resection was associated with a trend toward better long-term survival in the trial with the largest number of patients.