If you are diagnosed with cancer and undergo treatment, ultimately, you will want to know if the treatment was successful and if your cancer is gone. With some types of cancer, blood tests can determine if a person has responded to treatments or if cancer remains in the body; however, this is not the case when it comes to soft tissue sarcomas and many other solid tumors.

Soft tissue sarcomas are rare cancers that arise from the body’s connective tissue, including muscle, fat, joints, tendons, nerves and blood vessels. After treatment, the only way to detect residual tumor, or cells from the tumor that spread to other areas of the body, is through a physical exam and advanced imaging such as MRI, CT or PET/CT scans.

“We need more accurate ways to detect sarcomas before the cancer is large enough to show up on imaging,” said Meena Bedi, MD, a radiation oncologist and sarcoma specialist with the Froedtert & the Medical College of Wisconsin Clinical Cancer Center at Froedtert Hospital. “Instead of relying on scans and a physical exam to see if a patient’s sarcoma returns, which is the current standard of care, we want to be able to tell patients sooner, ‘you are cancer-free.’”

If cancer is still present, detecting it earlier may allow for more prompt intervention in hopes to prevent the progression of disease.

Testing for genetic material

Dr. Bedi believes the key to solving this problem comes down to circulating tumor DNA (ctDNA), genetic material released by cancer cells into the blood stream. Dr. Bedi is leading a clinical trial to determine if the presence and levels of ctDNA in a sarcoma patient’s blood following treatment provide information on the success of the individual’s treatment.

“Other studies have looked at the presence of ctDNA in patients with pancreatic cancer and lung cancer,” Dr. Bedi said. “Those studies showed that if ctDNA was present in the blood following treatment, the prognosis for those patients was worse.”

New data on sarcomas

Although rare, soft tissue sarcomas account for the majority of sarcomas with about 12,750 new patients expected to be diagnosed in 2019 in the United States. Developing a blood test for soft tissue sarcomas is particularly complex because there are more than 50 subtypes of the disease and countless mutations possible. In other words, no two people will have exactly the same sarcoma.

“There are so many sarcomas, and each one responds to therapies very differently,” Dr. Bedi said. “Two people may have the same subtype of sarcoma, but because their mutations may be different, they could need two different treatments. Because there are many subtypes of this rare cancer, little data exists, which is why more sarcoma research is desperately needed.”

The Froedtert & MCW Sarcoma Program at the Clinical Cancer Center has the only team in the country focusing its research on ctDNA for sarcomas. The clinical trial is enrolling two groups of patients. The first group will have localized disease, meaning their sarcoma has not yet spread to other parts of the body. The second group will have stage IV disease (which mean sarcoma has spread to other areas of the body). The team will test for ctDNA in the blood of both groups of people before treatment and at regular intervals following treatment.

“I am optimistic that using ctDNA will eventually be a game changer for sarcoma patients across the country,” Dr. Bedi said. “If we can detect sarcoma in the blood sooner than we currently do using imaging, we are hopeful that we can improve survival rates.”

The clinical trial studying a blood test for sarcoma is only available through the Froedtert & MCW Cancer Network.

Sheila Broadnax