Defining distal splenopancreatectomy by the mesopancreas.

BACKGROUND: The implementation of the pathologic CRM (circumferential resection margin) staging system for pancreatic head ductal adenocarcinomas (hPDAC) resulted in a dramatic increase of R1 resections at the dorsal resection margin, presumably because of the high rate of mesopancreatic fat (MP) infiltration. Therefore, mesopancreatic excision (MPE) during pancreatoduodenectomy has recently been promoted and has demonstrated better local disease control, fueling the discussion of neoadjuvant downsizing regimes in MP + patients. However, it is unknown to what extent the MP is infiltrated in patients with distal pancreatic (tail/body) carcinomas (dPDAC). It is also unknown if the MP infiltration status affects surgical margin control in distal pancreatectomy (DP). The aim of our study was to histopathologically analyze MP infiltration and elucidate the influence of resection margin clearance on recurrence and survival in patients with dPDAC. Furthermore, the results were compared to a collective receiving MPE for hPDAC. METHOD: Clinicopathological and survival parameters of 295 consecutive patients who underwent surgery for PDAC (n = 63 dPDAC and n = 232 hPDAC) were evaluated. The CRM evaluation was performed in a standardized fashion and the specimens were examined according to the Leeds pathology protocol (LEEPP). The MP area was histopathologically evaluated for cancerous infiltration. RESULTS: In 75.4% of dPDAC patients the MP fat was infiltrated by vital tumor cells. The rates of MP infiltration and R0CRM- resections were similar between dPDAC and hPDAC patients (p = 0.497 and 0.453 respectively). MP- infiltration status did not correlate with CRM implemented resection status in dPDAC patients (p = 0.348). In overall survival analysis, resection status and MP status remained prognostic factors for survival. In follow up analysis. surgical margin clearance in dPDAC patients was associated with a significant improvement in local recurrence rates (5.2% in R0CRM- resected vs. 33.3 in R1/R0CRM + resected, p = 0.002). CONCLUSION: While resection margin status was not affected by the MP status in dPDAC patients, the high MP infiltration rate, as well as improved survival in MP- dPDAC patients after R0CRM- resection, justify mesopancreatic excision during splenopancreatectomy. Larger scale studies are urgently needed to validate our results and to study the effect on neoadjuvant treatment in dPDAC patients.

Mesopancreatic excision for pancreatic ductal adenocarcinoma improves local disease control and survival.

BACKGROUND: Survival in ductal adenocarcinoma of the pancreatic head (hPDAC) is poor. After implementation of the circumferential resection margin (CRM) into standard histopathological evaluation, the margin negative resection rate has drastically dropped. However, the impact of surgical radicality on survival and the influence of malignant infiltration of the mesopancreatic fat remains unclear. At our institution, a standardized dissection of the mesopancreatic lamina and peri-pancreatic vessels are obligatory components of radical pancreatoduodenectomy. The aim of our study was to histopathologically analyze mesopancreatic tumor infiltration and the influence of CRM-evaluated resection margin on relapse-free and overall survival. METHOD: Clinicopathological and survival parameters of 264 consecutive patients who underwent surgery for hPDAC were evaluated. RESULTS: The rate of R0 resection R0(CRM-) was 48.5%, after the implementation of CRM. Mesopancreatic fat infiltration was evident in 78.4% of all consecutively treated patients. Patients with mesopancreatic fat infiltration were prone to lymphatic metastases (N1 and N2) and had a higher rate of positive resection margin (R1/R0(CRM+)). In multivariate analysis, only R0 resection was shown to be an independent prognostic parameter. Local recurrence was diagnosed in only 21.1% and was significantly lower in patients with R0(CRM-) resected hPDACs (10.9%, p < 0.001). CONCLUSION: Mesopancreatic excision is justified, since mesopancreatic fat invasion was evident in the majority of our patients. It is associated with a significantly improved local tumor control as well as longer relapse-free and overall survival.

[Anatomic study and clinical practice of mesopancreas and total mesopancreatic excision].

Objective: To explore the anatomical characteristics of the mesopancreas, to define the range of the total mesopancreas excision and to evaluate the feasibility, safety and effectiveness in the treatment of pancreatic cancer. Methods: A regional anatomical and pathological study was performed on 14 cadavers with large slices and paraffin sections. The clinical and pathological data of 58 consecutive patients underwent total mesopancreas excision for pancreatic head carcinoma from January 2013 to December 2015 were prospectively collected and analysed. The perioperative morbidity, mortality and clinical outcomes of patients underwent total mesopancreas excision were compared with the patients underwent conventional pancreaticoduodenectomy from January 2010 to December 2012. Results: The mesopancreas located in the retropancreatic area, extending from the head, neck, and uncinated process of pancreas to the aorto-caval groove, in which there were loose areolar tissue, adipose tissue, nerve plexus, lymphatic and capillaries. Although no fibrous sheath or fascia like mesocolorectum was found around the structures, a relatively fixed extent could be defined according to its embryologic and anatomic characters. In clinical practice, total mesopancreas excision was classified into two levels according to the extent of resection in this series: level Ⅰ was a"standard total mesopancreas excision" or"total mesopancreas excision in a narrow sense" , which was similar to the extent of standard resection from consensus statement of ISGPS. Level Ⅱ was defined as any procedure extending the range of level Ⅰ, called the"extended total mesopancreas excision" or"total mesopancreas excision in a broad sense". In TMpE group, the intraoperative blood loss( (461.4±184.5)ml vs. (532.2±319.8)ml, P=0.301), operation time( (368.6±92.5)minutes vs. (397.1±112.7)minutes, P=0.559), total complication rate (39.7% vs. 51.2%, P=0.250), fistula mortality (25.9% vs. 30.2%, P=0.628) were all reduced. There were significantly higher R0 rate (91.4% vs.76.7%, P=0.041) and more harvested lymph nodes (16.2 vs. 11.4, P=0.000) and lower total and local recurrence: rate (half-year local recurrence rate: 7.8% vs. 23.7%, P=0.036; one-year local recurrence rate: 18.2% vs. 39.5%, P=0.018) and longer disease-free survival (16.9 months vs. 13.4 months, P=0.044) and overall survival(22.5 months vs. 19.9 months, P>0.05) were also found in the study group. Conclusions: Mesopancreas is different from mesorectum since it has no fascial envelop, which should be regarded as a surgical concept, rather than an anatomical structure. Total mesopancreas excision is safe and feasible for pancreatic head cancer and probably helps to increase the R0 resection rate and improve the clinical outcomes.

Neoadjuvant Treatment Lowers the Risk of Mesopancreatic Fat Infiltration and Local Recurrence in Patients with Pancreatic Cancer.

BACKGROUND: Survival following surgical treatment of ductal adenocarcinoma of the pancreas (PDAC) remains poor. The recent implementation of the circumferential resection margin (CRM) into standard histopathological evaluation lead to a significant reduction in R0 rates. Mesopancreatic fat infiltration is present in ~80% of PDAC patients at the time of primary surgery and recently, mesopancreatic excision (MPE) was correlated to complete resection. To attain an even higher rate of R0(CRM-) resections in the future, neoadjuvant therapy in patients with a progressive disease seems a promising tool. We analyzed radiographic and histopathological treatment response and mesopancreatic tumor infiltration in patients who received neoadjuvant therapy prior to MPE. The aim of our study was to evaluate the need for MPE following neoadjuvant therapy and if multi-detector computed tomographically (MDCT) evaluated treatment response correlates with mesopancreatic (MP) infiltration. METHOD: Radiographic, clinicopathological and survival parameters of 27 consecutive patients who underwent neoadjuvant therapy prior to MPE were evaluated. The mesopancreatic fat tissue was histopathologically analyzed and the 1 mm-rule (CRM) was applied. RESULTS: In the study collective, both the rate of R0 resection R0(CRM-) and the rate of mesopancreatic fat infiltration was 62.9%. Patients with MP infiltration showed a lower tumor response. Surgical resection status was dependent on MP infiltration and tumor response status. Patients with MDCT-predicted tumor response were less prone to MP infiltration. When compared to patients after upfront surgery, MP infiltration and local recurrence rate was significantly lower after neoadjuvant treatment. CONCLUSION: MPE remains warranted after neoadjuvant therapy. Mesopancreatic fat invasion was still evident in the majority of our patients following neoadjuvant treatment. MDCT-predicted tumor response did not exclude mesopancreatic fat infiltration.

Mesopancreas in pancreatic cancer: where do we stand - review of literature.

Pancreatic cancer is associated with poor prognosis and surgery remains the main modality of treatment. Negative resection margin is an important prognostic factor for survival. Retropancreatic margin or the medial margin is the most common site of positive resection margin. Mesopancreas was proposed in analogy with mesorectum, which is considered as a fusion fascia formed embryologically during the development of pancreas. This mesopancreas lies posterior to the pancreas and contains pancreaticoduodenal vessels, lymphatics, nerve plexus and loose areolar tissue. Various technical modifications were proposed for better dissection of mesopancreas like posterior approach and artery first approach. There is an increased rate of R0 resection by these technical modifications but whether this will turn to increase in survival rates is yet to be established.