For the first time, scientists have shown how mothers may be able to pass cancerous cells on to their children during birth. The new research describes two cases where children may have acquired lung cancer by inhaling cancer cells from their mothers’ uterine cervical tumors when they cried for the first time.
While this remains an incredibly rare way to get cancer, the researchers say their work highlights another good reason why people should get the human papillomavirus (HPV) vaccine, which can prevent most cases of cervical cancer.
The study, led by the National Cancer Center in Tokyo, is published in the New England Journal of Medicine. It tells the story of two boys who started to fall ill at 23 months and 6 years old, respectively, developing symptoms such as cough and chest pain, and were quickly diagnosed with lung cancer. After the children were born, it was also discovered that both mothers had cervical cancer.
The cases were initially thought to be coincidental, but unusual similarities started to emerge between the mothers and their children. Tumors from both the mother and the child were positive for HPV type 16, one of the most high-risk HPV types that can lead to cervical cancers and pre-cancerous cervical lesions. Next-generation sequencing of the tumors also revealed the boys’ tumors had the same genetic mutations as those found in the cancers of their mothers.
Furthermore, the boys’ tumors lacked the Y chromosome. Since human males typically have one Y chromosome and one X chromosome, while females typically have two X chromosomes, this indicated the tumor had come from their maternal side.
It is known that cancer can spread to unborn children via the placenta in rare instances, however, the researchers argue that something different occurred in these two cases. They note how the tumors were seen only in the lungs and were localized along the airway. This, they argue, suggests the mothers’ cancerous cells were present in the amniotic fluid, secretions, or blood from the cervix and were inhaled by the babies as they were born.
It’s also pretty unusual that one of the patients was 6 years old when their cancer first became apparent since it must have originated shortly before or during their birth. The researchers believe this is because the transmitted tumors had sparked an alloimmune response, which is how the immune system deals with donor tissues and blood transfusion, and his body was trying to keep the cancer at bay.
One of the boys was treated with a cancer immunotherapy drug Opdivo and the other had his lung cancer surgically removed. Unfortunately, both mothers later died from cervical cancer.
It's important to stress that these cases of acquired cancer cells are exceptionally rare and shouldn't keep expecting parents up at night. HPV is really common — almost every sexually-active person will come into HPV at some time in their life — and often harmless, but a few types of the virus can increase the risk of cervical cancer. Fortunately, vaccines against HPV have been found to dramatically reduced cervical cancer rates. The researchers maintain that the most simple and effective way to prevent similar cases such as this is for people to receive the HPV vaccine.
“Preventing the onset of cervical cancer in mothers is expected to help prevent the transfer of mother-derived cancers to children. You can now be vaccinated against the human papillomavirus (HPV). It is expected that the incidence of cervical cancer will decrease as the number of vaccinated people increases,” the National Cancer Center in Tokyo said in a press release.