Researchers Identified Rare In-Utero Cancer Transmission
A study traced a cancer spread between twin sisters through their shared placenta during gestation.
Updated on Oct. 9, 2026 in Cancer
Scientists have confirmed a rare instance of cancer transferring from one fetus to another within the womb. The study, published in Nature Communications, highlights a complex biological exchange between twins.
Why it matters
This case provides evidence that cancer cells can cross the placenta between twins, complicating clinical understanding of fetal tumors. Understanding these mechanisms helps researchers distinguish between independent and transferred disease.
A genetic analysis of 33 total samples from two twins diagnosed with undifferentiated sarcomas confirmed that tumor cells originated in one twin and spread to the other. The study traced this transfer using accumulated DNA mutations to establish cellular family trees.
The players
Wellcome Sanger Institute
A genomics and genetics research organization that contributed to the study.
Great Ormond Street Hospital
A specialized children's hospital that participated in the research.
University of Cambridge
A public research university that co-authored the findings on fetal cancer transmission.
The details
Researchers determined the cancer originated in one twin during the first trimester before transferring to the other by the late second trimester. By analyzing DNA mutations across tumor, normal tissue, and placental samples, the team tracked the migration of cells. The twins also exchanged normal cells, as evidenced by one twin possessing approximately 75 percent of cells from the other in a spleen sample, identifying the placenta as the route for this cellular movement.
Timeline
The cancer is estimated to have originated in the first twin at the end of the first trimester.
The transfer to the second twin likely occurred during the late second trimester.
A fetal MRI scan detected a facial mass in one twin at 33 weeks of gestation.
Both sisters were diagnosed with sarcomas at birth.
Health Landscape
The study marks a unique application of genomic sequencing techniques typically used by the Wellcome Sanger Institute to investigate rare fetal pathology. This finding expands the medical understanding of how the shared placental environment can facilitate the transmission of cellular disease.
This case highlights the highly specialized nature of fetal tumor diagnosis, which often involves complex imaging and genetic testing. Parents facing similar high-risk prenatal diagnoses should consult with maternal-fetal medicine specialists and pediatric oncologists.
The takeaway
This rare event demonstrates that cellular transfer between twins is a biological possibility during gestation. Discuss any concerns regarding fetal imaging results with your obstetrician or a maternal-fetal medicine specialist.
Further reading
For more information on the latest research in this field, visit our Cancer section.
Source note: This article includes information reported by ScienceAlert.
