Overview
A review protocol based on PRISMA was designed prior to initiating this review (supplemental file 1). The protocol was unable to be registered as no applicable veterinary registry existed at the time of writing and human registries will only permit registration of either human studies or animal studies related to human health. Systematic searches of digital bibliographic databases were performed in order to identify studies pertaining to treatment of dogs with cutaneous MCT. Two authors performed relevance screenings to identify which manuscripts should be included in the review. Data abstraction was performed and the quality of individual studies and the strength of the body of evidence for utilization of surgical margins < 3cm for canine cutaneous MCTs was assessed.
Literature search
Electronic literature searches were performed in PubMed (1950 to present), Web of Science (1900 to present), Medline (1950 to present), CAB Abstracts (1973 to present), conducted in June 2016. Search terms that described the population, intervention of surgical resection and comparison (<3cm vs. ≥ 3cm) of lateral surgical margins were identified in the Medical Subject Headings (MeSH) database. The complete search string utilized was {[dog OR canine] AND [mast cell tumor* OR mastocytoma OR mastocytosis OR mast-cell sarcoma] AND [surgical margin OR incomplete margin OR dirty margin OR surgical resection OR surgical excision OR surgery OR biopsy] AND [recurrence OR local control OR neoplasm recurrence, local OR neoplasm, residual]}.
The citations retrieved from each search were stored in commercially available reference management softwarea. Electronic and hand scanning of the resultant citation library containing the citations from all searches was performed to identify any duplicate citations. If duplicity or multiplicity of the same citation was present, only the most complete citation was retained. Reviewers performed hand searching of article reference lists as the review progressed to identify other potentially relevant citations. If a potentially relevant citation was identified by this method, it was manually added to the citation library on the reference management software.
Relevance screenings
The citations recovered from the literature search process were screened to identify and remove citations that were not relevant to the review. Eligible studies were primary research studies (experimental or observational) published in English that reported outcomes of surgical treatment of cutaneous MCT in dogs. In addition, these studies needed to assess surgical margins < 3cm. Studies that were case reports, review articles, not written in the English language, or those that did not report outcomes (histologic completeness of surgical margins and local recurrence) of surgical treatment or that had an incomplete description of surgical margins used were excluded from the review. The relevance screening was a two-stage process.
Stage 1 of relevance screening involved two reviewers (XXX and XXX) independently reviewing each abstract title. Citations proceeded to the second stage of review if both reviewers agreed the citation described primary research assessing the outcome of surgical treatment of cutaneous MCT or did not contain enough information to determine eligibility. When the two reviewers did not initially agree about a citation, a discussion was raised and consensus was determined. If the manuscripts met all inclusion criteria determined for stage 1 of relevance screening and the study was published in English, the manuscript could advance to the next stage of the review. Stage 2 of relevance screening involved evaluation of the full manuscript using the full inclusion criteria and was conducted independently by the same reviewers (XXX and XXX). Similarly, any disagreements were resolved through discussion and consensus between reviewers.
Data abstraction and quality assessment
For manuscripts that passed through both stages of review, data were abstracted by one reviewer (XXX). The results of the abstraction were assessed by a second reviewer (XXX) to determine accuracy and completeness. The data abstracted from individual studies included the author list, years the study was performed and reported, study design, study population, sample size, institution where the study was performed, number of subjects treated with surgery in study, number of dogs with Patnaik histologic grades5 (PG) 1, 2 and 3 or Kiupel low and high histologic grade22, number of dogs with each grade treated with surgery, and the surgical margins utilized. Data were grouped by the surgical margin (<3cm and ≥ 3cm margins) and study specific estimates of proportions of incomplete surgical resection and clinically detectable local recurrence at the surgical site (when treated with surgery alone) were abstracted when available. Incomplete resection was defined as determination on histopathologic assessment of surgical margins of the presence of mast cells extending to surgical margins. Clinically detected local recurrence was defined as a mass arising within 3cm of the surgical site or scar. Confirmatory testing was not required for inclusion.
The individual study quality was determined based on multiple criteria including: 1) representativeness of study population; 2) selection of study participants; 3) data collection methods utilized; and 4) statistical and analytic methods used. For assessment of the quality of the entire body of evidence, guidelines developed by The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group were used.23
Data synthesis
The data were described in the form of the resultant narrative review.