Dr. Nancy Joseph, professor of pathology at the University of California, San Francisco, explains why, even within the world of neuroendocrine cancer, that there are many different kinds of zebras.

I think we like to talk about zebras in the neuroendocrine world because neuroendocrine neoplasms are actually pretty rare and they're also heterogeneous.

Lots of people may have heard of like a neuroendocrine cancer, but that can mean many different things.

And so You know, in general, what they all share in common is expression of neuroendocrine markers like synaptophysin or chromogranin.

But some of these are epithelial neoplasms and others are more mesenchymal neoplasms.

And even within the epithelial group, some are, we like to call them tumors and others we like to call carcinomas.

So even though neuroendocrine cancer as a group may be starting to become better recognized, there's still many different flavors happening.

Dr. Joseph says one of the biggest questions researchers are now trying to answer is whether tumors can actually evolve from one type into another.