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Importance: Rectal cancers occupy the eighth position worldwide for new cases and deaths for both men and women. These cancers have a high tendency to form metastases in the mesorectum but also in the lateral lymph nodes. The therapeutic approach for the involved lateral lymph nodes remains controversial. Objective: We performed a systematic review and meta-analysis to assess the prevalence of metastatic lateral lymph nodes in patients with lateral lymph node dissection (LLND) for rectal cancer, which seems to be a fundamental and necessary criterion to discuss any possible indications for LLND. Methods: Data sources–study selection–data extraction and synthesis–main outcome and measures. We searched MEDLINE, EMBASE and COCHRANE from November 1, 2018, to November 19, 2018, for studies reporting the presence of metastatic lateral lymph nodes (iliac, obturator and middle sacral nodes) among patients undergoing rectal surgery with LLND. Pooled prevalence values were obtained by random effects models, and the robustness was tested by leave-one-out sensitivity analyses. Heterogeneity was assessed using the Q-test, quantified based on the I2 value and explored by subgroup analyses. Results: Our final analysis included 31 studies from Asian countries, comprising 7599 patients. The pooled prevalence of metastatic lateral lymph nodes was 17.3% (95% CI: 14.6–20.5). The inter-study variability (heterogeneity) was high (I2 = 89%). The pooled prevalence was, however, robust and varied between 16.6% and 17.9% according to leave-one-out sensitivity analysis. The pooled prevalence of metastatic lymph nodes was not significantly different when pooling only studies including patients who received neoadjuvant treatment or those without neoadjuvant treatment (p = 0.44). Meta-regression showed that the pooled prevalence was associated with the sample size of studies (p < 0.05), as the prevalence decreased when the sample size increased. Conclusion: The pooled prevalence of metastatic lateral lymph nodes was 17.3% among patients who underwent rectal surgery with LLND in Asian countries. Further studies are necessary to determine whether this finding could impact the therapeutic strategy (total mesorectal excision with LLND versus total mesorectal excision with neoadjuvant radiochemotherapy). [ABSTRACT FROM AUTHOR]

Background Lymph node involvement in pancreatic adenocarcinoma is a key prognostic factor. Therefore, extending the number of lymph node stations excised in pancreatoduodenectomy may be beneficial to patients with pancreatic adenocarcinoma. This systematic review and meta-analysis examines the outcomes of extended versus standard lymphadenectomy in the published literature. Methods A meta-analysis of randomized controlled trials ( RCTs) comparing extended with standard lymphadenectomy in patients undergoing pancreatoduodenectomy for pancreatic adenocarcinoma was performed. Perioperative outcomes were assessed as pooled odds ratios (ORs) and weighted mean differences. Overall survival was analysed for patients with positive and negative lymph nodes. Results were reported according to the PRISMA statement. Results Five RCTs were included, accounting for 724 patients. Extended lymphadenectomy was associated with greater operative time [mean difference: 63 min, 95% confidence interval ( CI) 29-96; P < 0.001], increased need for blood transfusions (mean difference: 0.20, 95% CI 0.01-0.30; P = 0.030) and greater postoperative morbidity ( OR 1.5, 95% CI 1.25-2.00; P = 0.030), as well as with prolonged diarrhoea after circumferential autonomic nerve dissection around major vessels ( OR 12.2, 95% CI 5.3-28.5; P < 0.001). Median survival was similar across the groups in the whole cohort, as well as in subgroups of patients with, respectively, positive and negative lymph nodes. Conclusions Extended lymphadenectomy has a harmful impact on patients undergoing oncological pancreatoduodenectomy compared with standard lymphadenectomy. [ABSTRACT FROM AUTHOR]