Thankfully this rarely occurs, but so horrifying that it does. A study found that occasionally babies can contract cancer from their mothers during childbirth.
The Japanese study described the (rare) transmission of cervical cancer to two babies during birth, when the babies must have inhaled tumor cells as they were being born. Both later developed lung cancers, which were exact genetic matches to their mothers' cancers.
This is how rare it is: Approximately one in 1000 live births involves a mother who has cancer, but transmission of the cancer is estimated to only occur to one infant for every 500,000 mothers with cancer. 1 in 500,000. Most other cases have involved leukemia, lymphoma, and melanoma cancer cells crossing the placenta during pregnancy (transplacental transmission).
From Medical Xpress: Women may transmit cancer to infants in childbirth, reports suggest
In extremely rare instances, newborns can contract cancer from their pregnant moms during delivery, a new case report suggests.
Two boys, a 23-month-old and a 6-year-old, developed lung cancers that proved an exact genetic match to cervical cancers within their mothers at the time of birth, Japanese researchers report. It appears that the boys breathed in cancer cells from their mothers' tumors while they were being born, cancer experts say.
"In our cases, we think that tumors arose from mother-to-infant vaginal transmission through aspiration of tumor-contaminated vaginal fluids during birth," said lead researcher Dr. Ayumu Arakawa, a pediatric oncologist with the National Cancer Center Hospital in Tokyo.
The small number of previously observed cases typically have involved cancer cells traveling across the placenta and into the still-developing fetus, researchers said. Leukemia, lymphoma and melanoma are the most common cancers that children contract through suspected transplacental transmission.
These are the first cases in which newborns appear to have contracted lung cancer by breathing in cancer cells from cervical tumors, cancer experts said.
"I found it fascinating, personally. I didn't know this was possible," said Debbie Saslow, senior director of HPV-related and women's cancers at the American Cancer Society.
Most cervical cancers are caused by human papillomavirus (HPV), a virus against which there is an effective vaccine. Cases like this will become even rarer as more boys and girls are vaccinated against HPV, Saslow said.
Doctors discovered cancer in both lungs of the 23-month-old boy after his family took him to the hospital for a cough that had gone on for two weeks. His mother had received a diagnosis of cervical cancer three months after the infant's birth.
The 6-year-old boy went to a local hospital with chest pain on his left side, and a CT scan revealed a 6-centimeter mass in his left lung. His mother had a cervical tumor that was thought to be benign at the time of delivery; she died from cervical cancer two years after his birth.
"Neither mother was known to have a cervical cancer. The first patient had a negative pap smear, and the second had a cervical mass but it was thought to be benign. I don't know the obstetricians would have done anything differently based on the information they had," said Dr. Shannon Neville Westin, a gynecologic oncologist with the University of Texas MD Anderson Cancer Center.
Both boys still are alive following successful cancer treatment, the Japanese researchers said. The findings were reported Jan. 7 in the New England Journal of Medicine.
The New England Journal of Medicine: Vaginal Transmission of Cancer from Mothers with Cervical Cancer to Infants