New research led by cancer center Chief Translational Officer Nicholas Mitsiades shows that blood tests used to hunt for cancer DNA may help detect cancers faster and guide the use of targeted therapies.
The results of the study were published in NPJ Precision Oncology. The international, peer-reviewed journal focuses on targeted cancer care based on the genetics of individual patients.
Mitsiades and his research team from several cancer centers across the country made a potentially life-saving discovery. While monitoring a patient for prostate cancer DNA after treatment, the researchers identified genetic material coming not from prostate cancer, but from a type of cancer that starts in or near the urinary bladder. Their analysis showed that DNA from the cancer could be detected in the blood at least 18 months before clinical diagnosis becomes possible using conventional screening such as computed tomography (CT).
After Mitsiades’ team discovered the asymptomatic urothelial cancer, they used data from the blood sample to develop a targeted treatment plan based on the newly detected cancer’s specific gene mutations.
DNA sequencing in blood provides a fast, less-invasive method for cancer detection
DNA from some cancers may circulate in a patient’s blood and can be extracted from a simple blood sample. Scientists can genetically sequence the DNA — determining the order of the building blocks of genetic instructions — and characterize the cancer based on what’s found in the blood sample.
"We want to collect information about a patient's cancer in the least invasive way possible," Mitsiades said. "The more we can learn about a patient's cancer, the more we can treat it with safer and hopefully more effective drugs by targeting mutations that show up in the DNA sequencing."
Sequencing of tumor DNA circulating in the blood is a remarkable technological advancement. While a tissue biopsy is needed for a tumor’s initial diagnosis, repeated collection of samples of tumor tissue is painful and inconvenient. By sequencing tumor DNA from blood samples, a patient’s tumor can be monitored with little discomfort. It also can reveal mutations that suggest a particular treatment path. “Driver mutations” that spur the growth of cancer can be found in blood samples and indicate an aggressive cancer long before it can be detected on other types of tests.
The patient in the study already had been treated for prostate cancer with radiation and androgen deprivation therapy and was taking part in a long-term study to track potential cancer recurrence. The research team took blood samples at regular intervals and analyzed them for cancer DNA fragments that would indicate his prostate cancer had returned.
Using circulating tumor DNA analysis to improve patient treatment
“It appears that by sequencing DNA circulating in the blood, we can see evidence of cancer growth months or years before it shows up in CT scans,” Mitsiades said. “Now we need clinical trials that will examine whether, by acting upon DNA information from a patient’s blood, we can help them live longer.”
For years, the gold standard of care for cancer treatment has been to treat patients after tumors showed visible signs of growth on scans.
Mitsiades and his colleagues believe that precision oncology tools like circulating tumor DNA sequencing create opportunities to respond to cancer earlier. These tools could help by identifying malignancies that have acquired mutations causing resistance to current therapy. Physicians then could quickly apply alternative, targeted therapies.
At UC Davis Comprehensive Cancer Center, genetic tests already are offered regularly to patients who also have the option to participate in precision oncology research at the cancer center.
ACKNOWLEDGMENTS
Research study coauthors from Baylor College of Medicine and Ben Taub General Hospital include Quillan Huang, Heidi Dowst, Neda Zarrin-Khameh, Attiya Batool Noor, Patricia Castro, Michael E. Scheurer, Guilherme Godoy and Marta P. Mims. Coauthor Irene Mitsiades is affiliated with Harvard Medical School and Boston University
