  Increased proliferation is a key driver of tumorigenesis, and quantification
of mitotic activity is a standard task for prognostication. The goal of this
systematic review is scholarly analysis of all available references on mitotic
activity in feline tumors, and to provide an overview of the measuring methods
and prognostic value. A systematic literature search in PubMed and Scopus and a
manual search in Google Scholar was conducted. All articles on feline tumors
that correlated mitotic activity with patient outcome were identified. Data
analysis revealed that of the eligible 42 articles, the mitotic count (MC,
mitotic figures per tumor area) was evaluated in 39 instances and the mitotic
index (MI, mitotic figures per tumor cells) in three instances. The risk of
bias was considered high for most studies (26/42, 62%) based on small study
populations, insufficient details of the MC/MI methods, and lack of statistical
measures for diagnostic accuracy or effect on outcome. The MC/MI methods varied
markedly between studies. A significant association of the MC with survival was
determined in 21/29 (72%) studies, while one study found an inverse effect.
There were three tumor types with at least four studies and a prognostic
association was found in 5/6 studies on mast cell tumors, 5/5 on mammary tumors
and 3/4 on soft tissue sarcomas. The MI was shown to correlate with survival by
two research groups, however a comparison to the MC was not conducted. An
updated systematic review will be needed with of new literature for different
tumor types.
