This article states that the data is peer-reviewed. The link is to a pre-print (not a finished article) that specifically states it is NOT peer-reviewed.
There are some very curious aspects of this, and the full data are not available to me to investigate more closely. (It appears that some commenters have seen the entire data, but I can't find it).
The curious aspects are this- 1) Schwannoma of the heart - this is a vanishingly rare tumor in humans. In 35 years of medical practice, in a position where I might well see such a tumor, I have never seen one. The scant information does not reveal if there was one mouse or several with this tumor. This may indicate that the mouse model is invalid to extrapolate to humans and/or this strain may be genetically prone to such tumors. 2) Gliomas - these are also rare, but not so rare as schwannomas of the heart. That said, 2500 individuals would not be expected to produce enough gliomas to be statistically significant. Were there any gliomas in the control animals? If so - this strain may be genetically susceptible to gliomas. There is no information.
In summary - this reads as a non-reviewed piece of work, that has been picked up by the media for its sensationalism. (some 117 news sites have picked it up). It is not to be believed.