While blood tests for some types of cancer indicate whether or not malignant cells remain after treatment, this has not been the case with soft tissue sarcomas and many other solid tumors.
“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 more prompt intervention in hopes of preventing the progression of disease.
Testing for genetic material
Dr. Bedi is leading a clinical trial to determine if the presence and levels of circulating tumor DNA (ctDNA) in a sarcoma patient’s blood following treatment can 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
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.
“Each sarcoma 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 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. The second group will have stage IV disease. The team will test for ctDNA in the blood of both groups 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 we can improve survival rates.”
