2.3. Data Extraction

The titles and abstracts were assessed by two independent authors (M.G.F. and M.A.) against the inclusion and exclusion criteria in order to arrive at a final list of articles. Any disagreement was resolved by a third independent reviewer (C.K.). Each included manuscript was read to determine ultimate inclusion in the final analysis. From the manuscripts, the following information was extracted: author names, title, year of publication, country, study centre, study design, age, gender, primary tumour location, tumour differentiation, TNM staging and R0 resection for primary tumour, and chemotherapy and RT regimen. Results were stratified by three main groups: (1) synchronous RPLNM; (2) metachronous RPLNM; and (3) synchronous and metachronous RPLNM (presented as combined outcome data in studies). Preoperative imaging modality (computed tomography, CT; magnetic resonance imaging, MRI; positron emission tomography, PET; lymph node biopsy) was recorded to define the extent of RPLNM, information on patient selection criteria, anatomical boundaries of RPLND, number of lymph nodes harvested, and lymph node yield. Outcome measures were hospital length of stay, postoperative morbidity (Clavien-Dindo classification [22,23]), postoperative 90-day mortality, DFS, OS, re-recurrence rate and site. The median, 3-year, and 5-year DFS and OS were recorded where available.