Dr Ravin Ratan Breaks Down Classification of Soft Tissue Sarcomas

In this interview to learn more about soft tissue sarcomas (STS), their classification and diagnosis, and where they originate compared with organ-based cancers, Ravin Ratan, MD, MEd, associate professor, Department of Sarcoma Medical Oncology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, broke down the differences between STS—which arises in the body’s connective tissue—and carcinomas, which are primarily organ based but can also arise in the various linings and tubes and ducts that exist in the body. He also underscores the importance of collaboration when dealing with rare cancers like STS, which often can occur anywhere in the body.

“I think that one of the advantages of being in a large place is instead of just using my own experience,” he explained, “we have sort of organized ways of making sure that we're leveraging the experience of the 10 people that I work with that also just see sarcomas to try and make sure that we're making informed decisions for our patients.”

Transcript

How does STS develop within the body?

When most people think about cancers, and they're thinking about things like pancreas cancer, breast cancer, lung cancer, cancers of the head and neck, what we're usually talking about is cancers either of the functional part of an organ or the cancers of the various linings and tubes and ducts that exist in the body. The medical term for those types of cancers that are mostly organ based is carcinoma. Carcinomas are cancers of organs and cancers of the linings of things, like airways and so forth. That's the majority of cancers in adults.

Then you have the blood cancers, things like leukemias and lymphomas, which I think a lot of people have some familiarity with. And then the remaining 1% of cancers in adults are cancers that arise in connective tissue—things like muscle, and fat, and bone. It’s those cancers that I focus on. Those are sarcomas, cancers of connective tissue. Unlike organ-based cancers—obviously a cancer of the breast is always going to rise in a breast, for example—you have connective tissue throughout your entire body; inside organs, outside of organs, in the arms, in the legs, as well as sort of inside the body cavity.

And so sarcomas, unlike carcinomas that are sort of named for where they tend to occur, very often can occur anywhere in the body, and there are specific subtypes of soft tissue sarcomas that have a preference for certain parts of the body. But I think that's something that people struggle with sometimes. We don't name our cancers for the location in which they arose, right? So someone comes in with an unclassified pleomorphic sarcoma of the thigh. Sometimes they're sort of wondering what to tell people. “Do I tell people I have thigh cancer? What does that even mean?”

The way that we classify these tumors is by the way they look under the microscope and how we think they're going to behave. And so yes, this tumor happened to be in your thigh, but it could just as easily have been in your arm or the muscles of your body wall. We focus less on that location and more on what it looks like under the microscope—even though the location has a huge impact on what we might do for treatment. The 9-cm unclassified sarcoma in the thigh is something that can be managed very easily with surgery many times. Conversely, a 9-cm tumor that's located in the head-neck region with a lot of sensitive structures is much more likely to be challenging from a surgical standpoint. And so the location matters, but we tend to talk about it a little bit less than we do for other cancers and that can confuse people sometimes.

That 1% of cancers that are sarcomas are then divided into anywhere from 50 to 100 different subtypes depending on how you do it. So each of those is a fraction of 1%. And so when you're someone like me, who sees only sarcomas, there are some that are sort of a larger slice of that 1% pie. Things like liposarcomas, leiomyosarcoma, gastrointestinal stromal tumors, another relatively common sarcoma, although quite rare by the standards that we judge most cancers. But then you have some that are truly rare, where even in a sarcoma center, I might see them once a year or once every few years, or in some cases, once or twice in a career. And I think that one of the advantages of being in a large place is instead of just using my own experience, we have sort of organized ways of making sure that we're leveraging the experience of the 10 people that I work with that also just see sarcomas to try and make sure that we're making informed decisions for our patients.