Two children in Japan may have developed lung cancer after inhaling cancer cells from their mothers at birth, according to a new case report.
About 1 in 1,000 babies are born to mothers with cancer, but only about one in 500,000 of these newborns develops cancer from their mothers. Although these cases are extremely rare, the researchers knew that the transfer could happen if the cancer cells, traveling in the mother’s blood, enter the placenta.
Now researchers in Japan have identified a previously unknown route of transmission: two babies born to mothers with cervical cancer may have developed lung cancer after “aspirating” tumor cells that were present in the amniotic fluid, secretions or blood from the cervix, wrote the authors in a case study published on January 7 in The new English medical journal.
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The cases involved a 23-month-old boy who went to a local hospital in Japan with a cough that did not break for two weeks and a 6-year-old boy who went to the hospital with chest pains. Both boys were diagnosed with lung cancer.
The 23-month-old boy’s mother was diagnosed with cervical cancer three months after the boy was born, but probably had a tumor at the time of his birth. The boy and his mother were treated with chemotherapy, various medications and surgeries to remove cancerous tissue; and while the boy’s cancer disappeared, the mother progressed and led to her death five months later.
The 6-year-old boy’s mother had a known cervical tumor during pregnancy, but it appeared stable and was not treated at the time, according to the report. After delivery, a biopsy revealed that she had cervical cancer; she died two years after surgery to remove the tumor. The boy passed chemotherapy among other treatments and had his left lung removed; he was followed for 15 months after surgery and remained cancer free, according to the report.
To understand the relationship between tumors in mothers and their children, the researchers compared the tumor tissues and normal tissues of two young patients and their mothers, looking specifically for mutations in 114 cancer-related genes. They found that boys ‘lung tumors had many genetic similarities to their mothers’ cervical tumors.
The boys’ tumors lacked the Y chromosome – one of the two sexual crossomes passed from father to son – meaning that the tumor was probably inherited from the mothers. They also found that the tumors had characteristics similar to the tumors found in the mothers of each of the boys, such as mutations that occur in cells called somatic cells that are not normally transmitted to their children. Lung tumors also contained small genetic mutations similar to the mother’s that were not found in the child’s other tissues. The tumors of both boys also contained DNA from the human papillomavirus (HPV), which probably causes most cases of cervical cancer.
The “detailed genomic examination and comparison of the mother’s and child’s cancer cells provide unmistakable evidence” that the two tumors are from the same clone, or group of identical cells, said Sir Mel Greaves, founding director of the Center for Evolution and Cancer in The London Cancer Research Institute, which was not part of the study. “The story is very reliable.”
Because these patients developed tumors specifically in the lungs and not throughout the body, as is common in most other documented cases of cancer spreading from mother to child, babies probably “aspirated” their mothers’ tumor cells during birth, they wrote the authors.
It is “quite likely, though not likely” that this is what happened, Greaves told Live Science by email. Although extremely rare, these cases indicate that it is possible to transfer cancer to babies during birth, which is why the authors recommend Caesarean sections for mothers with cervical cancer.
“This is a very interesting report,” said Dr. Theodore Laetsch, a pediatric oncologist and director of the Very Rare Malignant Tumors Program at Children’s Hospital in Philadelphia, who was also not involved in the study. It is “clear from the genetic data that both babies’ cancers came from cancer in their mothers.”
But “I still think it’s possible that the cancer has crossed the placenta, as has been described in other patients, and that the cancer cells have only grown in the lungs for other reasons,” wrote Laetsch in an email to Live Science.
Originally published on Live Science.