874 Abnormal cell-free DNA screening in the setting of malignancy: could cancer stage and type matter?

With increasing cfDNA aneuploidy screening, there is a corresponding increase in “false positive” and “non-reportable” results the setting of maternal malignancy. We hypothesize that these may be further characterized depending on stage type cancer. This was retrospective review cases with screening diagnosis malignancy during pregnancy. abstracted history, diagnoses, results, fetal outcomes from medical record. identified 13 2015-2019 Four patients did not pursue screening. Three underwent first trimester one quad (all normal). Five had (Table 1), three whom an abnormal result: case III rectal adenocarcionoma resulted “non-reportable”, IV serous ovarian carcinoma as “monosomy 13”, acute myeloid leukemia “concerning for mosaic monosomy X”. There were two non-metastatic breast cancer both normal results. No fetuses genetic abnormality. Corroborating previous isolated reports, we demonstrated secondary to Our data suggest cancers hematologic spread are likely detected by cfDNA, while those less tumor shedding not. Ultimately, prove useful identifying certain types Conversely, indicated known it invalidate interpretation status. Larger patient cohorts needed characterize association different pattern well implement appropriate protocols diagnostic work up.