Introduction: National guidelines give recommendations regarding cancer surveillance follow-up. In many early staged cancers radiographic imaging and labs are not routinely recommended unless patients are symptomatic. This can cause a gap in care because commonly when patients present symptomatically, they have progressed and transitioned to later-stage cancer. This study demonstrates how circulating tumor DNA (ctDNA) can be used alongside current guidelines to help screen patients for recurrence in the surveillance setting.
Methods: A retrospective chart review was performed. Fifty-five charts were reviewed of patients who received ctDNA testing drawn in follow-up after their primary tumor or metastatic disease was rendered surgically or radiographically disease-free. A customized signature profile, using the sixteen most prevalent genomic markers from a patient's primary tumor or biopsy, is developed by whole-exome sequencing. Serial blood draws are then drawn to assess for specific DNA markers using polymerase chain reaction (PCR) assays.
Results: Fifty-five charts were reviewed in patients who had stage I-III breast, pancreatic, melanoma, and colorectal cancer. Of the fifty-five, a total of seven had a positive test. Of the seven positive tests, six patients were found to have recurrent/metastatic disease. One positive test was performed four weeks postoperatively but by the second draw ten weeks postoperatively had non-detectable ctDNA. The remaining forty-eight patients had non-detectable ctDNA levels and to date have not had any evidence of recurrence based on standard follow-up guidelines.
Conclusion: The utilization of ctDNA in the surveillance setting can be used to help detect recurrence in the surveillance setting.
Keywords: cancer surveillance; circulating tumor DNA.