Study: Sarcoma spread between identical twins via placenta before birth
Genetic analysis reveals that an undifferentiated sarcoma tumor originating in one identical twin spread across the shared placenta to the other twin during pregnancy, presenting a rare prenatal cancer transmission documented in a study published in Nature Communications.
- Researchers utilized full genome sequencing on tumor samples, normal tissue, and the placenta to reconstruct the intrauterine disease pathway of identical twins Amelia and Amaya.
- Magnetic resonance imaging at 33 weeks of gestation initially identified a facial mass in one fetus, with subsequent postnatal examinations confirming soft-tissue sarcomas in both infants.
- Mutational timeline modeling indicates that the rare transplacental metastasis occurred once during the late second trimester, accompanied by the incidental transfer of normal cells.
Prenatal Magnetic Resonance Imaging Findings at 33 Weeks
The clinical timeline began during the thirty-third week of gestation. Fetal magnetic resonance imaging detected a distinct mass located on the face of one of the twins. Approximately one week after birth, attending physicians confirmed the presence of tumors in both infants. Diagnostic evaluations classified the malignancy as an undifferentiated sarcoma, which is a rare form of soft-tissue cancer.
Tumor Cells Spread Between Twins via Shared Placenta
Investigators sought to determine whether the malignancies developed independently in each child or spread from one twin to the other. By comparing genetic variations across tumor samples, normal tissue, and the placenta, researchers mapped the origin of the cellular pathology. The analysis established that the tumor cells originated in the first twin and reached the second twin via the shared placenta prior to birth. Computational modeling of genetic mutations suggested that the metastasis took place during the late second trimester, though this temporal estimate represents a mathematical model rather than a direct real-time observation.
Non-Malignant Cells Also Crossed Between Twins During Gestation
Beyond mapping the oncogenic lineage, the genomic investigation revealed that non-malignant cells also crossed between the twins during gestation. Following the short lifespans of the infants, who passed away shortly after birth, the family consented to post-mortem examinations to support ongoing medical research. As noted across the published findings, this transplacental transmission remains an exceptional anomaly and does not imply that cancer generally spreads between individuals or that monochorionic twin pregnancies inevitably result in disease transfer.
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