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Scientists Trace How Cancer Passed Between Twins Before Birth : ScienceAlert (opens in a new tab)

sciencealert.com · 2026-10-08

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The study doesn't address any of the story's claims. We found the paper, but it doesn't report the details the story leads with.

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6 claims in this story

Showing all 6 claimsChoose a verdict to focus the list.

Claim 1 of 6Not coveredA facial mass detected before birth led to early delivery of identical twin sisters, and tumors were found in both babies after birth.View evidenceHide evidence

Why this verdict

The abstract-level profile supports that this was a monozygotic newborn twin case involving a soft-tissue cancer shared in utero, but it does not report a prenatal facial mass, early delivery, or the post-birth clinical detection sequence. Those clinical details cannot be verified from the supplied abstract-depth evidence.

1

Study evidence

The tumour originated in one twin and then spread transplacentally to the co-twin in utero, as inferred from multi-sample whole-genome sequencing and phylogenetic reconstruction.

“we perform whole genome sequencing on multiple tumour, normal, and placental samples to reconstruct the phylogeny of a soft tissue cancer that spread in utero between monozygotic twins”
Claim 2 of 6Not coveredThe study in Nature Communications says the cancer began in one sister and passed to the other in the womb, most likely through a single transfer late in the second trimester.View evidenceHide evidence

As statedsingle transfer late in the second trimester

Why this verdict

The core claim that the tumour originated in one twin and spread transplacentally to the co-twin in utero via a single seeding event is supported by the abstract-level profile. However, the specific timing stated as 'late in the second trimester' is not provided in the abstract profile, which explicitly notes that quantitative timing estimates and uncertainty are unavailable at this depth.

1

Study evidence

The tumour originated in one twin and then spread transplacentally to the co-twin in utero, as inferred from multi-sample whole-genome sequencing and phylogenetic reconstruction.

“we perform whole genome sequencing on multiple tumour, normal, and placental samples to reconstruct the phylogeny of a soft tissue cancer that spread in utero between monozygotic twins”
Claim 3 of 6Not coveredThe tumors were reported as undifferentiated sarcomas, and all tumor samples carried the same MN1-ZNF341 gene fusion.View evidenceHide evidence

Why this verdict

The abstract-level profile describes a soft-tissue cancer shared between monozygotic newborn twins, but it does not identify the tumours as undifferentiated sarcomas or report an MN1-ZNF341 fusion in all tumour samples. These molecular and histopathologic specifics are not verifiable from the supplied profile.

1

Study evidence

The tumour originated in one twin and then spread transplacentally to the co-twin in utero, as inferred from multi-sample whole-genome sequencing and phylogenetic reconstruction.

“we perform whole genome sequencing on multiple tumour, normal, and placental samples to reconstruct the phylogeny of a soft tissue cancer that spread in utero between monozygotic twins”
Claim 4 of 6Not coveredResearchers sequenced 10 tumor samples, 12 normal tissue samples from the twins, and 11 placental samples, plus 12 placental samples enriched for placenta-forming cells.View evidenceHide evidence

As stated10 tumor samples, 12 normal tissue samples, 11 placental samples, 12 enriched placental samples

Why this verdict

The profile supports use of multi-sample whole-genome sequencing across tumour, normal, and placental samples, but the abstract-depth evidence does not give the exact sample counts or the stated enriched placental sampling. The numerical details are therefore not verifiable at this depth.

1

Study evidence

The tumour originated in one twin and then spread transplacentally to the co-twin in utero, as inferred from multi-sample whole-genome sequencing and phylogenetic reconstruction.

“we perform whole genome sequencing on multiple tumour, normal, and placental samples to reconstruct the phylogeny of a soft tissue cancer that spread in utero between monozygotic twins”
2

Study evidence

Multi-sample WGS-based lineage reconstruction indicates unexpected asymmetrical contributions of embryonic lineages to the placenta and to each monozygotic twin, challenging the classical symmetric model of twinning.

“This generalisable and scalable approach additionally allows us to dissect the earliest stages of twinning, revealing unexpected asymmetrical contributions of embryonic lineages to the placenta and each twin and challenging the classical model of twinning.”
Claim 5 of 6Not coveredThe analysis suggested normal cells had also moved in the opposite direction, with a spleen sample from twin A showing about 75 percent of sampled cells originating in twin B.View evidenceHide evidence

As statedaround 75 percent

Why this verdict

The profile supports analyses of embryonic and placental lineage contributions and asymmetry, but it does not mention normal-cell movement in the opposite direction, a spleen sample from twin A, or an approximately 75% contribution from twin B. Those details cannot be checked from the abstract-level profile.

1

Study evidence

Multi-sample WGS-based lineage reconstruction indicates unexpected asymmetrical contributions of embryonic lineages to the placenta and to each monozygotic twin, challenging the classical symmetric model of twinning.

“This generalisable and scalable approach additionally allows us to dissect the earliest stages of twinning, revealing unexpected asymmetrical contributions of embryonic lineages to the placenta and each twin and challenging the classical model of twinning.”
Claim 6 of 6Not coveredThe authors also inferred that the twins' earliest cell lineages contributed unevenly to their bodies and placenta, favoring an earlier embryonic split than the classical model predicts.View evidenceHide evidence

Why this verdict

The abstract-level profile supports the broader point that the authors inferred unexpected asymmetrical embryonic lineage contributions to the placenta and each twin, challenging the classical model of twinning. However, the more specific framing that the pattern favored an earlier embryonic split than the classical model predicts is not stated in the supplied abstract-depth profile.

1

Study evidence

Multi-sample WGS-based lineage reconstruction indicates unexpected asymmetrical contributions of embryonic lineages to the placenta and to each monozygotic twin, challenging the classical symmetric model of twinning.

“This generalisable and scalable approach additionally allows us to dissect the earliest stages of twinning, revealing unexpected asymmetrical contributions of embryonic lineages to the placenta and each twin and challenging the classical model of twinning.”
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Context layer

What the story left out

Important study details the story did not include.

  • Inference limitations: the abstract profile lacks methodological detail on sample counts, sequencing depth, mutation counts, phylogenetic model parameters, robustness metrics, and sensitivity analyses.

    The story includes some inferential caveats, but it does not acknowledge the broader abstract-level limitation that robustness metrics and sensitivity details are not available in the supplied profile. This matters for interpreting the strength and precision of directionality, timing, and lineage-allocation claims.

    From Multi-sample whole-genome sequencing with phylogenetic reconstruction; secondary_data; multi-sample WGS lineage tracing

  • Generalizable/scalable approach: the paper presents the WGS lineage-tracing approach as generalizable and scalable for dissecting childhood tumour origins and early twinning processes.

    The story focuses on this twin case and its inferred transfer and lineage findings, but it does not appear to present the authors' broader claim that the approach is generalizable and scalable.

    From Multi-sample whole-genome sequencing with phylogenetic reconstruction; secondary_data; multi-sample WGS lineage tracing

5 things the story did carry across
  • Central tumour-phylogeny finding: multi-sample WGS was used to infer that the cancer originated in one twin and spread transplacentally to the co-twin in utero via a single seeding event.
  • Methodological basis: the paper used whole-genome sequencing across multiple tumour, normal, and placental samples with phylogenetic and molecular-timing inference.
  • Developmental-lineage finding: the approach revealed unexpected asymmetrical embryonic lineage contributions to the placenta and each twin, challenging the classical twinning model.
  • Timing inference: the paper reports molecular timing of tumour diversification and transplacental spread, but the abstract profile does not provide quantitative timing estimates, confidence intervals, or details sufficient to assess precision.
  • Single-case limitation: the evidence comes from one reported monozygotic twin pair, limiting generalizability to other pregnancies or twin cancers.
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Study layer

Study at a glance

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Pieces of work

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Evidence read

study summary

Lead result

secondary data

1Lead resultsecondary dataReconstruct the phylogeny of a soft tissue cancer shared in utero between monozygotic newborn twins to determine the tumour’s origin (which twin), timing of diversification, and whether transplacental spread occurred once or multiple times.Multi-sample whole-genome sequencing with phylogenetic reconstructionExpand

In plain English

Using whole-genome sequencing of multiple tumour, normal, and placental samples from a monozygotic newborn twin pair, the authors reconstruct the tumour phylogeny and infer that the cancer arose in one twin, diversified, and spread transplacentally to the co-twin in utero via a single seeding event. The sequencing-based approach also permits analysis of early embryonic lineage contributions, revealing asymmetrical inputs to placenta and twins and challenging classical twinning models.

Key findings

  • The tumour originated in one twin and then spread transplacentally to the co-twin in utero, as inferred from multi-sample whole-genome sequencing and phylogenetic reconstruction.
  • Molecular timing analysis of the reconstructed phylogeny indicates diversification and transplacental spread occurred at specific points during development and supports a single seeding event rather than multiple independent transfers.
“we perform whole genome sequencing on multiple tumour, normal, and placental samples to reconstruct the phylogeny of a soft tissue cancer that spread in utero between monozygotic twins”
What this piece can’t prove
  • Abstract lacks methodological detail (sample counts, sequencing depth, mutation counts, phylogenetic methods and model parameters, and uncertainty measures).

3 further details could not be confirmed from the summary.

2secondary dataUse multi-sample whole-genome sequencing across twins and placenta to infer early embryonic/twinning lineage relationships, including asymmetric embryonic contributions to placenta and each twin, challenging the classical model of twinning.secondary data; multi-sample WGS lineage tracingExpand

In plain English

Using multi-sample whole-genome sequencing of tumour, normal, and placental samples from monozygotic twins, the authors reconstruct developmental phylogenies and report unexpected asymmetrical contributions of embryonic lineages to the placenta and to each twin; they present this as challenging the classical model of twinning and state the approach is generalisable and scalable.

Key findings

  • Multi-sample WGS-based lineage reconstruction indicates unexpected asymmetrical contributions of embryonic lineages to the placenta and to each monozygotic twin, challenging the classical symmetric model of twinning.
  • The WGS phylogenetic approach enabled reconstruction of a tumour origin in one twin and timing of diversification and a single transplacental spread to the co-twin; the authors repurpose the same approach to make inferences about early embryonic lineage allocation.
“This generalisable and scalable approach additionally allows us to dissect the earliest stages of twinning, revealing unexpected asymmetrical contributions of embryonic lineages to the placenta and each twin and challenging the classical model of twinning.”
What this piece can’t prove
  • Apparent inference stems from analyses of one twin pair (implied by case-report framing), which limits assessment of how generalisable the observed embryonic lineage asymmetry is across pregnancies.

2 further details could not be confirmed from the summary.

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Open the paper in Tessa

Embryonic origin of cancer in newborn twins

Nature Communications · 2026

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Crossref, PubMed, Europe PMC · 16 candidate papers

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