Vaginal Transmission of Cancer from Mothers with Cervical Ca
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Researchers report two cases of pediatric lung cancer that have resulted from the vaginal transmission of uterine cervical cancer cells from mother to infant, either during, or just prior to, birth. The study is published in the New England Journal of Medicine.

Maternal–fetal transfer of cancer cells is exceptionally rare ~ 1 per 500,000 mothers with cancer, whereas ~ 1 in 1000 live births involve a mother with a diagnosis of cancer. Eighteen cases of maternal–fetal transfer have previously been reported – all of which are believed to have occurred via transplacental mother-to-fetus transmission. However, transmission via the birth canal during vaginal delivery is also theoretically possible. For example, if the mother has cervical cancer, transformed cells residing in the fluids within the birth canal could enter the lungs of the infant during delivery.

The discovery of the two cases (both male) was made during routine sequencing of paired samples of cancerous and normal tissue, which was part of a prospective clinical trial. The first boy received a diagnosis of lung cancer at 23-months and the second was diagnosed at six years of age. Both mothers were diagnosed with cervical cancer shortly after the birth of the children (within three months).

The authors were able to confirm mother-to-infant transmission based on various findings. The tumors in both boys lacked the Y chromosome. Tumor cells from the infants also shared multiple somatic mutations and single nucleotide polymorphism alleles with the cervical tumor cells of each mother. In addition, the human papillomavirus (HPV) genome was detected in the boys’ tumor cells. This was a notable finding, as HPV infection is linked to cancer; Types 16 and 18 are responsible for ~ 70% of cervical cancers. Tumor growth in both cases was localized to the bronchi, the main airways leading from the trachea to the lungs, suggesting that the tumors arose from aspiration of tumor-contaminated fluids during vaginal delivery.

In the publication, the authors note that next generation sequencing “may be a useful tool to diagnose cancer that is transmitted from mothers to infants and to understand the prevalence of this transmission.”