Recently discovered commonalities and genetic differences among the most common types of canine soft tissue sarcomas, a common and life-threatening tumor, could pave the way for more accurate diagnosis and better treatments in the future.
Using next-generation sequencing techniques and computational approaches, a team of Washington State University researchers and veterinarians examined the genetic makeup of the three most common tumor subtypes and identified several therapeutic targets that could form the basis of new treatments. They detailed their findings in a study published in the journal PLoS One.
“The different subtypes of soft tissue sarcomas can look so similar that even trained pathologists have trouble telling them apart. Yet it turns out that they are not all the same – they are a very diverse group of cancers,” said Eric Shelden, associate professor in WSU’s School of Molecular Biosciences and corresponding author of the study.
In the United States, up to 95,000 dogs are diagnosed with this cancer each year and 20-30% die from it. There are several subtypes of sarcomas, however, because they have similar characteristics and are difficult to diagnose, they are treated similarly and often unsuccessfully.
Rance Sellon, veterinary oncologist at WSU and co-author of the study, said the study results suggest that a “one size fits all” treatment approach may no longer be appropriate for patients, and clinicians may need to work more closely with veterinary pathologists to identify tumor subtypes for more accurate diagnosis and to investigate and identify more effective treatment options.
“From a clinical perspective, the results of this study suggest that our view of this tumor type should perhaps change, and we should seek to make better distinctions between the different subtypes, with the ultimate goal of better define treatment and prognosis,” he said. said.
Previous studies have looked at potential causes of soft tissue sarcomas and examined genetic markers to identify subtypes of soft tissue sarcomas. The WSU study, however, was the first to examine gene expression patterns in canine soft tissue sarcomas using RNA sequence analysis of tumor samples to differentiate tumors, understand the biology that determines their behavior and identify candidates for drug therapies.
“We looked at thousands of genes and their expression patterns at once, and then we tried to determine computationally if there are differences between different tumor types, and there are,” Shelden said. “While it will probably be a few years before the effect of this study is really felt in a clinical setting, the hope is that it will make people realize that these tumors should not just be treated the same way. way, because they are in fact biologically different.”
Shelden said follow-up studies are needed to validate the results and identify which drugs are better suited to treat different tumors.
Sellon estimated that WSU’s veterinary teaching hospital sees one or two dogs a week with soft tissue sarcomas. He noted that the tumors can be difficult to treat and the prognosis varies depending on a number of variables, such as tumor size and grade. Treatment usually involves surgical removal of the tumor followed by radiation therapy.
“Surgical cure may be difficult or impossible, depending on the size and location of the tumor, as these tumors are known for their locally invasive behavior which can make it difficult to acquire ‘clean’ surgical margins – margins with a adequate amount of normal tissue surrounding the edges of the tumor,” Sellon said. “Radiation therapy can be effective in treating residual disease, but for some dogs recurrence may still be seen after surgery and radiation therapy.”
In addition to Sheldon and Sellon, co-authors include postdoctoral scientist Lydia Lam and senior science assistant Mark Wildung at WSU’s School of Molecular Biosciences; oncologists Tien Tien and Janean Fidel of WSU’s Department of Veterinary and Clinical Sciences; and Professor Laura White of the Washington Animal Disease Diagnostics Laboratory.
The study was supported by grants from the Marge Crowley Canine Cancer Research Endowment and the Dorothy Shea Brink Memorial Fund.