Ovarian cancer relapses may be effectively monitored and, possibly, detected early by analyzing patients’ DNA in blood samples, Mayo Clinic researchers report in the study, “Quantification of Somatic Chromosomal Rearrangements in Circulating Cell-Free DNA from Ovarian Cancers,” published in the journal Science Reports.
When tumor cells are dying, they release DNA into the blood stream that differs from the DNA derived from non-cancerous tissue. This DNA “signature” can be used as a “liquid biopsy” biomarker, the researchers said. Using blood samples collected before and after surgery, and next-generation whole genome sequencing (known as mate-pair sequencing),they compared DNA from 10 patients’ liquid blood biopsies to DNA from tumor tissue samples.
“In this study, the blood drawn before and after surgery and the surgical tissue was used to identify DNA fragments with abnormal junctions that can only be seen in this patient’s tumor DNA,” George Vasmatzis, PhD, with the Department of Laboratory Medicine and Pathology, said in a press release.
Before surgery, tumor-specific DNA fragments were detected in the blood of eight patients. After surgery, three of these eight still had detectable levels of circulating tumor DNA consistent with the presence of disease. The other five patients had no tumor DNA detectable in the post-surgical blood collection, which was also consistent with their lack of detectable disease.
Detection of circulating tumor DNA after surgery warns for a closer patient follow-up to avoid recurrence. In addition, detecting tumor DNA may suggest that the tumor failed to respond to a given drug, allowing for a particular treatment to possibly be replaced by another, more effective therapy.
Ovarian cancer patients may especially benefit from this type of blood analysis to monitor tumor relapse and therapeutic efficacy because, compared to other cancer patients, OC patients have relatively high amounts of circulating tumor DNA. Moreover, they also have a great risk of recurrence following initial chemotherapy.
“Next-generation mate-pair sequencing was used to identify specific DNA changes of the tumor to create an individualized monitoring panel for liquid biopsy. This allows us to shape treatment to the individual patient rather than using a standard treatment that may not work for everyone,” Vasmatzis said.
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