Are veterinary professionals reading veterinary cancer research wrong?

If you've ever had a client walk in clutching a stack of printed studies about spay/neuter and cancer risk, you're not alone. That stack, and the statistics inside it, has become a familiar fixture in veterinary oncology appointments. The problem, according to Phil Bergman, DVM, MS, PhD, DACVIM (Oncology), is that not everything in that pile deserves equal weight.

The issue, he says, isn't bad science. It's that clinicians and clients alike treat all published studies as equivalent and breeders are capitalizing on that blind spot, circulating data about a 3-to-5-times increase in lymphoma and mast cell tumor risk after spay/neuter as if it's settled fact. Bergman points out that the best available studies—those with thousands of dogs—tell a very different story. In the case of mast cell tumors, two large studies, one out of North Carolina State and another conducted with Antech, actually found roughly a 2.5-fold reduction in risk associated with neutering. For lymphoma, a high-quality study showed about a 30% increase in risk for neutered females but a 40% decrease in males. "It can go both ways," Bergman said,¹ "but that's very different than the 3- to 5-fold that breeders like to quote."

He is careful to note that some associations do hold up under scrutiny: hemangiosarcoma and urothelial tumors like transitional cell carcinoma of the bladder do appear to carry a credible neuter-related risk based on stronger data. But the sweeping claims, he argues, don't.¹

Below is a partial transcript, edited lightly for clarity.

dvm360: What is the most common way that practitioners misinterpret the data being presented in the new publications?

Bergman: Yeah, I think the disconnect is that, and I get why, because evaluating the scientific literature is hard. A lot of people, will skim the abstract and not get into the nitty gritty details of the paper, and I know that takes time, and a lot of us have less time as time goes on, it seems. And so I think what's happening is the misinterpretation that you talk about is more about essentially equating all studies as being equal, when we know that there's high quality journals and then there's medium quality journals and there's lower quality journals. We don't often talk about that, but as clinician scientists, we know in veterinary medicine we want to try to get our papers into the very best journals, and sometimes it's not of good enough quality, so you go down a tier, if it's not good enough to publish there, then you go down another tier, and it's not to knock on other journals, because I think everybody has their place, but to say one study is equivalent to another study couldn't be farther from the truth.

So, I think really, where the misinterpretation is, assuming that a study has to be good because it's been published, when there's varying levels of quality for the study that's being done, and so my real goal in the lecture is to say this is the most trustable data, and this is what I think you should trust. This stuff is so-so, and then this stuff is junk, and so be careful, because unfortunately that 3-5x increase in lymphoma and mast cell that's being highly, highly perpetuated by breeders, and because I'll see some of the data that you know that that stack of literature that is given to the client and they really hound on that 3-5x.

Reference

1. Bergman P, McCafferty C. Q&A with Philip Bergman, DVM, MS, PhD, DACVIM (Oncology). dvm360. Published February 4, 2026. Accessed June 23, 2026. https://www.dvm360.com/view/q-a-with-philip-bergman-dvm-ms-phd-dacvim-oncology-