Reassessment of the Optimal Number of Examined Lymph Nodes in Pancreatoduodenectomy for Pancreatic Ductal Adenocarcinoma

The Feasibility, Proficiency, and Mastery Learning Curves in 635 Robotic Pancreatoduodenectomies Following a Multicenter Training Program: "Standing on the Shoulders of Giants"

OBJECTIVE

To assess the feasibility, proficiency, and mastery learning curves for robotic pancreatoduodenectomy (RPD) in "second-generation" RPD centers following a multicenter training program adhering to the IDEAL framework.

BACKGROUND

The long learning curves for RPD reported from "pioneering" expert centers may discourage centers interested in starting an RPD program. However, the feasibility, proficiency, and mastery learning curves may be shorter in "second-generation" centers that participated in dedicated RPD training programs, although data are lacking. We report on the learning curves for RPD in "second-generation" centers trained in a dedicated nationwide program.

METHODS

Post hoc analysis of all consecutive patients undergoing RPD in 7 centers that participated in the LAELAPS-3 training program, each with a minimum annual volume of 50 pancreatoduodenectomies, using the mandatory Dutch Pancreatic Cancer Audit (March 2016-December 2021). Cumulative sum analysis determined cutoffs for the 3 learning curves: operative time for the feasibility (1) risk-adjusted major complication (Clavien-Dindo grade ≥III) for the proficiency, (2) and textbook outcome for the mastery, (3) learning curve. Outcomes before and after the cutoffs were compared for the proficiency and mastery learning curves. A survey was used to assess changes in practice and the most valued "lessons learned."

RESULTS

Overall, 635 RPD were performed by 17 trained surgeons, with a conversion rate of 6.6% (n=42). The median annual volume of RPD per center was 22.5±6.8. From 2016 to 2021, the nationwide annual use of RPD increased from 0% to 23% whereas the use of laparoscopic pancreatoduodenectomy decreased from 15% to 0%. The rate of major complications was 36.9% (n=234), surgical site infection 6.3% (n=40), postoperative pancreatic fistula (grade B/C) 26.9% (n=171), and 30-day/in-hospital mortality 3.5% (n=22). Cutoffs for the feasibility, proficiency, and mastery learning curves were reached at 15, 62, and 84 RPD. Major morbidity and 30-day/in-hospital mortality did not differ significantly before and after the cutoffs for the proficiency and mastery learning curves. Previous experience in laparoscopic pancreatoduodenectomy shortened the feasibility (-12 RPDs, -44%), proficiency (-32 RPDs, -34%), and mastery phase learning curve (-34 RPDs, -23%), but did not improve clinical outcome.

CONCLUSIONS

The feasibility, proficiency, and mastery learning curves for RPD at 15, 62, and 84 procedures in "second-generation" centers after a multicenter training program were considerably shorter than previously reported from "pioneering" expert centers. The learning curve cutoffs and prior laparoscopic experience did not impact major morbidity and mortality. These findings demonstrate the safety and value of a nationwide training program for RPD in centers with sufficient volume.

A dynamic analysis of empirical survival outcomes after pancreatectomy for pancreatic ductal adenocarcinoma

BACKGROUND

Survival outcomes after pancreatectomy for pancreatic ductal adenocarcinoma may be biased by right-censoring. We herein analyzed a large dataset with no censored events for up to 5 years and dynamically investigated the impact of known prognostic factors, accounting for unobserved tumor characteristics.

METHODS

Consecutive patients undergoing pancreatectomy from 2000 to July 2015 were included. The 1- to 5-year empirical survival rates were calculated, and factors associated with long-term survival (≥5 years) were analyzed using multivariable models. Dynamic analyses of survival and recurrence were conducted through landmarking, and the contribution of unobserved heterogeneity was estimated using frailty models.

RESULTS

The study population included 1,048 patients. The median follow-up was 30.4 months in the whole cohort and 97.2 months in survivors. The median survival was 30.4 months, with empirical 1- to 5-year rates of 85.5%, 59.6%, 43.2%, 32.1%, and 27.5%. A favorable pathological profile was associated with 5-year survival, albeit 25.7% of long-survivors received an R1 resection, and 28.8% had N2 disease. The median recurrence-free survival was 17.2 months. At landmark analyses, baseline prognostic lost strength over time, with no independent predictors of survival being identified in the sets of patients alive at 4 and 5 years. There was a significant amount of unobserved heterogeneity in the early postoperative period.

CONCLUSION

The 5-year post-pancreatectomy empirical survival was 27.5%. Dynamic analyses showed a time-varying structure of prognostic variables and a substantial impact of unobserved tumor characteristics that may drive the disease course under the selective pressure of surgical resection and adjuvant chemotherapy.

A Lymph Node Ratio Model for Prognosis of Patients with Pancreatic Neuroendocrine Tumors

The objective of this study was to determine the prognostic value of lymph node (LN) involvement and the LN ratio (LNR) and their effect on recurrence rates and survival in patients with pancreatic neuroendocrine tumors (PNETs) undergoing surgery. This single-center retrospective study reviewed the medical records of 95 consecutive patients diagnosed with PNETs who underwent surgery at our medical center between 1997 and 2017. The retrieved information included patient demographics, pathology reports, treatments, and oncological outcomes. Results: 95 consecutive potentially suitable patients were identified. The 78 patients with PNETs who underwent surgery and for whom there was adequate data were included in the analysis. Their mean ± standard deviation age at diagnosis was 57.4 ± 13.4 years (range 20-82), and there were 50 males (64%) and 28 females (36%). 23 patients (30%) had LN metastases (N1). The 2.5- and 5-year disease-free survival (DFS) rates for the entire cohort were 79.5% and 71.8%, respectively, and their 2- and 5-year overall survival (OS) rates were 85.9% and 82.1%, respectively. The optimal value of the LNR was 0.1603, which correlated with the outcome (2-year OS p = 0.002 HR = 13.4 and 5-year DFS p = 0.016 HR = 7.2, respectively, and 5-year OS and 5-year DFS p = 0.004 HR = 9 and p = 0.001 HR = 10.6, respectively). However, the multivariate analysis failed to show that the LNR was an independent prognostic factor in PNETs. Patients with PNETs grade and stage are known key prognostic factors influencing OS and DFS. According to our results, LNR failed to be an independent prognostic factor.

Delayed gastric emptying after pancreatoduodenectomy: One complication, two different entities

BACKGROUND

Delayed gastric emptying (DGE) is a common complication after pancreatoduodenectomy associated with a low complication burden but a prolonged hospital stay. The present study aimed to characterize DGE, with a particular focus on its subtypes and related predictors.

METHODS

A 2-center retrospective analysis was performed including consecutive pancreatoduodenectomy over 5 years. Primary delayed gastric emptying (pDGE) and secondary delayed gastric emptying (sDGE) were defined according to the presence of concomitant causing factors. Predictors of DGE, pDGE and sDGE were assessed through logistic regression.

RESULTS

Out of 1,170 patients considered, 188 developed delayed gastric emptying (16.1%). Most DGE (71.8%) were secondary. sDGE resolved later (P = .007), with hospital stay, duration of total parenteral nutrition, and of enteral nutrition being longer than for pDGE (all P < .005). Smoking status, total operative time, indication for surgery other than pancreatic cancer, estimated blood loss, and soft pancreatic texture were independent predictors of DGE. In the subgroup analysis of pDGE, smoking was the only independent predictor, whereas pylorus-preservation was a protective factor. Smoking, indication for surgery, estimated blood loss, soft gland texture, and main pancreatic duct diameter were independent predictors of sDGE.

CONCLUSION

DGE after pancreatoduodenectomy consists of 2 different subtypes. The primary form resolves earlier, and its occurrence might be reduced by pylorus preservation. For the secondary form, clinicians should focus on preventing and treating other trigger complications. The diagnosis of the DGE subtype has critical therapeutic implications and paves the way for further systematic studies.

Postoperative Chemotherapy is Associated with Improved Survival in Patients with Node-Positive Pancreatic Ductal Adenocarcinoma After Neoadjuvant Therapy

BACKGROUND

Postoperative chemotherapy following pancreatic cancer resection is the standard of care. The utility of postoperative chemotherapy for patients who receive neoadjuvant therapy (NAT) is unclear.

METHODS

Patients who underwent pancreatectomy after NAT with FOLFIRINOX or gemcitabine-based chemotherapy for non-metastatic pancreatic adenocarcinoma (2015-2019) were identified. Patients who received less than 2 months of neoadjuvant chemotherapy or died within 90 days from surgery were excluded.

RESULTS

A total of 427 patients (resectable, 22.2%; borderline resectable, 37.9%; locally advanced, 39.8%) were identified with the majority (69.3%) receiving neoadjuvant FOLFIRINOX. Median duration of NAT was 4.1 months. Following resection, postoperative chemotherapy was associated with an improved median overall survival (OS) (28.7 vs. 20.4 months, P = 0.006). Risk-adjusted multivariable modeling showed negative nodal status (N0), favorable pathologic response (College of American Pathologists score 0 & 1), and receipt of postoperative chemotherapy to be independent predictors of improved OS. Regimen, duration, and number of cycles of NAT were not significant predictors. Thirty-four percent (60/176) of node-positive and 50.1% (126/251) of node-negative patients did not receive postoperative chemotherapy due to poor functional status, postoperative complications, and patient preference. Among patients with node-positive disease, postoperative chemotherapy was associated with improved median OS (27.2 vs. 10.5 months, P < 0.001). Among node-negative patients, postoperative chemotherapy was not associated with a survival benefit (median OS, 30.9 vs. 36.9 months; P = 0.406).

CONCLUSION

Although there is no standard NAT regimen for patients with pancreatic cancer, postoperative chemotherapy following NAT and resection appears to be associated with improved OS for patients with node-positive disease.

Importance of Nodal Metastases Location in Pancreatoduodenectomy for Pancreatic Ductal Adenocarcinoma: Results from a Prospective, Lymphadenectomy Protocol

BACKGROUND

Implementing a prospective lymphadenectomy protocol, we investigated the nodal yields and metastases per anatomical stations and nodal echelon following upfront pancreatoduodenectomy (PD) for cancer. Next, the relationship between the extension of nodal dissection, the number of examined and positive nodes (ELN/PLN), disease staging and prognosis was assessed.

METHODS

Lymphadenectomy included stations 5, 6, 8a-p, 12a-b-p, 13, 14a-b, 17, and jejunal mesentery nodes. Data were stratified by N-status, anatomical stations, and nodal echelons. First echelon was defined as stations embedded in the main specimen and second echelon as stations sampled as separate specimens. Recurrence and survival analyses were performed by using standard statistics.

RESULTS

Overall, 424 patients were enrolled from June 2013 through December 2018. The median number of ELN and PLN was 42 (interquartile range [IQR] 34-50) and 4 (IQR 2-8). Node-positive patients were 88.2%. The commonest metastatic sites were stations 13 (77.8%) and 14 (57.5%). The median number of ELN and PLN in the first echelon was 28 (IQR 23-34) and 4 (IQR 1-7). While first-echelon dissection provided enough ELN for optimal nodal staging, the aggregate rate of second-echelon metastases approached 30%. Nodal-related factors associated with recurrence and survival were N-status, multiple metastatic stations, metastases to station 14, and jejunal mesentery nodes.

CONCLUSIONS

First-echelon dissection provides adequate number of ELN for optimal staging. Nodal metastases occur mostly at stations 13/14, although second-echelon involvement is frequent. Only station 14 and jejunal mesentery nodes involvement was prognostically relevant. This latter station should be included in the standard nodal map and analyzed pathologically.

Accurate Nodal Staging in Pancreatic Cancer in the Era of Neoadjuvant Therapy

BACKGROUND

Nodal disease is prognostic in pancreatic ductal adenocarcinoma (PDAC); however, optimal number of examined lymph nodes (ELNs) required to accurately stage nodal disease in the current era of neoadjuvant therapy remains unknown. The aim of the study was to evaluate the optimal number of ELNs in patients with neoadjuvantly treated PDAC.

METHODS

A retrospective study was performed on patients with PDAC undergoing resection following neoadjuvant treatment between 2011 and 2018. Clinicopathological data were extracted and analyzed.

RESULTS

Of 546 patients included, 232 (42.5%) had lymph node metastases. The median recurrence free survival (RFS) was 10.6 months (95% confidence interval: 9.7-11.7) and nodal disease was independently associated with shorter RFS (9.1 vs 11.9 months; p < 0.001). A cutoff of 22 ELNs was identified that stratified patients by RFS. Patients with N1 and N2 disease had similar median RFS (9.1 vs 8.9 months; p = 0.410). On multivariable analysis, ELN of ≥ 22 was found to be significantly associated with longer RFS among patients with N0 disease (14.2 vs. 10.9 months, p = 0.046). However, ELN has no impact on RFS for patients with N1/N2 disease (9.5 vs. 8.4 months, p = 0.190). Adjuvant therapy was associated with RFS only in patients with residual nodal disease.

CONCLUSIONS

Lymph node metastases remain prognostic in PDAC patients after neoadjuvant treatment. Among N0 patients, a cutoff of 22 ELN was associated with improved RFS and resulted in optimal nodal staging.

Surgery for pancreatic cancer: current controversies and challenges

Two areas that remain the focus of improvement in pancreatic cancer include high post-operative morbidity and inability to uniformly translate surgical success into long-term survival. This narrative review addresses specific aspects of pancreatic cancer surgery, including neoadjuvant therapy, vascular resections, extended pancreatectomy, extent of lymphadenectomy and current status of minimally invasive surgery. R0 resection confers longer disease-free survival and overall survival. Vascular and adjacent organ resections should be undertaken after neoadjuvant therapy, only if R0 resection can be ensured based on high-quality preoperative imaging, and that too, with acceptable post-operative morbidity. Extended lymphadenectomy does not offer any advantage over standard lymphadenectomy. Although minimally invasive distal pancreatectomies offers some short-term benefits over open distal pancreatectomy, safety remains a concern with minimally invasive pancreatoduodenectomy. Strict adherence to principles and judicious utilization of surgery within a multimodality framework is the way forward.