EP347/#879 Detection of progression or regression of gynecologic cancers by circulating tumor DNA (CTDNA)

Objectives

The use of post-operative circulating tumor DNA (ctDNA) to detect cancer recurrence has been reported in various studies but the literature describing variable changes in ctDNA is limited. The objective of this study is to describe the utility of single and serial ctDNA values in detecting the progression or regression of gynecological cancers.

Methods

This is a retrospective observational study including nineteen patients, aged >=18 years who had the ctDNA test completed at hematology/oncology clinic of William Beaumont – Royal Oak and Troy Hospitals, Michigan, USA.

Results

Among the nineteen patients, fifteen had breast, three had ovarian, and one had endometrial cancer. The median age at diagnosis was 57 years, and 73.7% of patients had either stage III or IV disease. Our primary endpoint, the correlation of single ctDNA results with imaging showing either progression or residual disease, showed a sensitivity and specificity of 100% and 93.3%, respectively. Secondarily, serial ctDNA analysis in ten patients revealed both sensitivity and specificity of 100% for up-trending ctDNA to detect progression, down-trending to detect regression, and negative results to detect the absence of disease. The positive ctDNA results detected disease progression with a median lead-time of 36.5 days compared to imaging.

Conclusions

Given the high sensitivity and specificity to detect disease progression and regression in gynecologic cancer by single and serial values in our study, we conclude that ctDNA can be a valid way to monitor for changes in disease status. Further clinical studies are required to prove the utility of ctDNA in detecting changes in disease status