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.