Radiofrequency-assisted transection of the pancreas vs stapler in distal pancreatectomy: a propensity score matched cohort analysis.

To demonstrate the efficacy of radiofrequency for pancreatic stump closure in reducing the incidence of postoperative pancreatic fistula (POPF) in distal pancreatectomy (DP) compared with mechanical transection methods. Despite all the different techniques of pancreatic stump closure proposed for DP, best practice for avoiding POPF remains an unresolved issue, with an incidence of up to 30% regardless of center volume or surgical expertise. DP was performed in a cohort of patients by applying radiofrequency to stump closure (RF Group) and compared with mechanical closure (Control Group). A propensity score (PS) matched cohort study was carried out to minimize bias from nonrandomized treatment assignment. Cohorts were matched by PS accounting for factors significantly associated with either undergoing RF transection or mechanical closure through logistic regression analysis. The primary end-point was the incidence of clinically relevant POPF (CR-POPF). Of 89 patients included in the whole cohort, 13 case patients from the RF-Group were 1:1 matched to 13 control patients. In both the first independent analysis of unmatched data and subsequent adjustment to the overall propensity score-matched cohort, a higher rate of CR-POPF in the Control Group compared with the RF-Group was detected (25.4% vs 5.3%, p = 0.049 and 53.8% vs 0%; p = 0.016 respectively). The RF Group showed better outcomes in terms of readmission rate (46.2% vs 0%, p = 0.031). No significant differences were observed in terms of mortality, major complications (30.8% vs 0%, p = 0.063) or length of hospital stay (5.7 vs 5.2 days, p = 0.89). Findings suggest that the RF-assisted technique is more efficacious in reducing CR-POPF than mechanical pancreatic stump closure.

Evaluation of the learning curve for laparoscopic pancreatoduodenectomy by CUSUM analyses. Cohort study.

INTRODUCTION: Laparoscopic pancreatoduodenectomy (LPD) remains an extremely demanding surgery. The purpose of this study was to describe the learning curve required for its safe implementation. METHODS: Fifty consecutive patients undergoing LPD were retrospectively reviewed. The learning curve was clustered into 4 groups: A, B and C (initial phase, n = 10 each) and D (consolidation phase, n = 20). Cumulative Sum (CUSUM) analysis was applied to operative time, conversion rate and severe postoperative complications. RESULTS: No significant differences were observed among groups and phases concerning specific and general postoperative complications, oncological outcomes or mortality. The conversion rate significantly reduced from 90% (9) in Group A to 40% (4) in Group C (p < 0.01). Operative time was longer in the consolidation phase (median of 506 vs 437 min, p < 0.01). Conversely, hospital stays were shorter during the consolidation phase (8 vs 15 days, p < 0.01). CUSUM analysis identified 20-25cases as being enough to complete the learning curve if operative time and severe complications are analysed, while 40 cases would be needed for considering the conversion rate. CONCLUSIONS: The learning curve in LPD can be completed after 20-25 procedures. This information will help to design programmes for introducing new surgeons to this technique.

Postoperative intra-abdominal infection is an independent prognostic factor of disease-free survival and disease-specific survival in patients with stage II colon cancer.

BACKGROUND: Recurrence occurs in up to 20% of patients with stage II colon cancer operated on for cure. Although postoperative intra-abdominal infection has been linked with an increased risk of recurrence, the association is controversial. The aim was to investigate the impact of postoperative intra-abdominal infection on disease-free survival and disease-specific survival in patients with stage II colon cancer. METHODS: Patients undergoing elective surgery for colon cancer stage II, between 2003 and 2014, were included. Patients with anastomotic leak or intra-abdominal abscess were included in the infection group. We used the Kaplan-Meier method to represent the distribution of survival and the Cox proportional hazards model to estimate the contribution of relevant clinicopathological factors with prognosis. RESULTS: Postoperative intra-abdominal infection was diagnosed in 37 of 363 (10.2%) patients. Perioperative blood transfusion was more frequent in patients with infection (p = 0.008). Overall 5-year disease-free survival rate was 85.1%. Disease-free survival at 5 years was lower in patients with postoperative intra-abdominal infection (52.8 vs 88.7%; p < 0.001), perineural invasion (p = 0.001), lymphovascular invasion (p = 0.001), pT4 (p = 0.013), and in patients with adjuvant chemotherapy (p = 0.013). Multivariate analysis showed that postoperative intra-abdominal infection (HR 4.275; p < 0.001), perineural invasion (HR 2.230; p = 0.007), and lymphovascular invasion (HR 2.052; p = 0.016) were all significant independent predictors of reduced disease-free survival. Regarding specific survival, independent significant prognostic factors were the number of lymph nodes, lymphovascular invasion, and postoperative intra-abdominal infection. CONCLUSION: In this series of patients with stage II colon cancer, postoperative intra-abdominal infection has an independent negative impact on disease-free survival and disease-specific survival.

Long-term effectiveness of irreversible electroporation in a murine model of colorectal liver metastasis.

Irreversible electroporation (IRE) has recently gained in popularity as an ablative technique, however little is known about its oncological long-term outcomes. To determine the long-time survival of animals treated with a high dose of IRE and which histological changes it induces in tumoral tissue, IRE ablation was performed in forty-six athymic-nude mice with KM12C tumors implanted in the liver by applying electric current with different voltages (2000 V/cm, 1000 V/cm). The tumors were allowed to continue to grow until the animals reached the end-point criteria. Histology was harvested and the extent of tumor necrosis was semi-quantitatively assessed. IRE treatment with the 2000 V/cm protocol significantly prolonged median mouse survival from 74.3 ± 6.9 days in the sham group to 112.5 ± 15.2 days in the 2000 V/cm group. No differences were observed between the mean survival of the 1000 V/cm and the sham group (83.2 ± 16.4 days, p = 0.62). Histology revealed 63.05% ± 23.12 of tumor necrosis in animals of the 2000 V/cm group as compared to 17.50% ± 2.50 in the 1000 V/cm group and 25.6% ± 22.1 in the Sham group (p = 0.001). IRE prolonged the survival of animals treated with the highest electric field (2000 V/cm). The animals in this group showed significantly higher rate of tumoral necrosis.

Irreversible electroporation of the liver: is there a safe limit to the ablation volume?

Irreversible electroporation is a fast-growing liver ablation technique. Although safety has been well documented in small ablations, our aim is to assess its safety and feasibility when a large portion of liver is ablated. Eighty-seven mice were subjected to high voltage pulses directly delivered across parallel plate electrodes comprising around 40% of mouse liver. One group consisted in 55 athymic-nude, in which a tumor from the KM12C cell line was grown and the other thirty-two C57-Bl6 non-tumoral mice. Both groups were subsequently divided into subsets according to the delivered field strength (1000 V/cm, 2000 V/cm) and whether or not they received anti-hyperkalemia therapy. Early mortality (less than 24 hours post-IRE) in the 2000 V/cm group was observed and revealed considerably higher mean potassium levels. In contrast, the animals subjected to a 2000 V/cm field treated with the anti-hyperkalemia therapy had higher survival rates (OR = 0.1, 95%CI = 0.02-0.32, p < 0.001). Early mortality also depended on the electric field magnitude of the IRE protocol, as mice given 1000 V/cm survived longer than those given 2000 V/cm (OR = 4.7, 95%CI = 1.8-11.8, p = 0.001). Our findings suggest that ionic disturbances, mainly due to potassium alterations, should be warned and envisioned when large volume ablations are performed by IRE.