The New England Journal of Medicine has a potentially disturbing report from Japan of two little boys, one aged two, the other aged six, diagnosed with lung cancer (they are not related) whose mothers had cervical cancer. Genome sequencing found that the tumours in the kids, although they seemed very different from the mothers, were genetically related to their mum's tumour. The assumption was that cancer cells had spread to the boys in the physical process of being born.

Dr Alison Brand is director of gynaecological oncology at Westmead Hospital in Sydney. Welcome to the Health Report, Alison.

Alison Brand: Thanks for having me.

Norman Swan: So have you ever heard of this before?

Alison Brand: No, I had not heard of this before this and, I have to say, it's virtually unheard of, and the New England Journal of Medicine, which is the peak journal in medicine to publish a case report. So you know if they've published this case report they have really examined the data very closely to verify that it is true. And I think we have to do believe some of it because it has been published in the New England Journal of Medicine.

Norman Swan: Let me just divert from the core story here, which is about cervical cancer moving to the kids and getting into their lungs. You're a gynaecological surgeon, you do a lot of surgery, what's the story with gynaecological seeding and surgery? There has been a lot of discussion about that, whether in fact you can spread cancer with surgery itself.

Alison Brand: The old wives' tale was that once you open up the belly and let the air in, then the cancer just spreads terribly, and of course we know that's not true. That really came from the fact that when patients had operations many years ago, they found cancer but then they couldn't do much about it, there was no chemotherapy or there was no radiotherapy. So really this whole business of surgery spreading cancer is probably not true at all. We do know that cancer from the mum can sometimes cross the placenta and get into babies, but that's usually haematologic malignancies.

Norman Swan: So it's leukaemia.

Alison Brand: Leukaemia, that's right, and otherand basically the babies then have widespread disease because it got into their bloodstream and then went throughout the body. These particular two case reports are really unusual because it doesn't look like it came transplacentally or through the placenta, it looks like it came as the baby has passed through the birth canal, and landed in the lung, which is the kind of closest place that the babies could breathe in some of the cells that were in the vagina as they pass through the birth canal.

Norman Swan: And because of that you wouldn't think it was human papilloma virus related, which is the cause of cervical cancer, because it was the actual tumour itself that got transmitted.

Alison Brand: Yes, that's right, although we haven't often thought that cancer is catching. I think that's the one thing that we've said; you can't touch someone who has cancer and then catch it, and in many ways you catch lots of viruses, and women can pass their HPV infections in some rare cases to their babies. And so this is unusual in that the cancer has really been caught from the mother and that's highly unusual.

I guess when we look at this we have to look atas we examine any reports, we have to say is this biologically plausible, and I guess in rare cases it is biologically plausible, although you mostly expect that the tumour cells on the top of tumours are really those ones that are often non-viable or not living and therefore can't attach to something and grow there. But I think that the next generation sequencing that they have done here really suggests to us that maybe there is some truth to all of this, albeit rare, rare, rare.

Norman Swan: Is it routine to screen for cervical cancer in pregnancy?

Alison Brand: It is routine that patients should have had a recent screen prior to their pregnancy, and if they haven't, to have one done during pregnancy. What you have to remember though, Norman, is certainly the mother of the first patient had had a normal cervical screen seven months prior to delivering her baby, and it's important because she had a very rare neuroendocrine tumour, so a very rare type of cervical tumour that probably wouldn't have been picked up by screening anyway. But those are very rare tumours, and the vast majority of cervical cancers can be picked up by screening, and certainly are much better picked up by the new screening test that we have that looks at HPV presence.

Norman Swan: And before we go, just tell usbecause the screening program has changed, it now happens every five years if I remember rightly, and you are checking for HPV. So, just give us a very brief outline of the screening program now.

Alison Brand: So it used to be that we looked at the cells on the cervix to check to see whether or not they had precancerous changes. That had up to a 30% false negative rate, and therefore we had to screen more often to make sure that we didn't miss anything. Now we check by looking at what we call high risk HPV virus, which is human papilloma virus, which is known to cause cervical cancer, and we check for that high risk HPV, and because the test is so sensitive, then if there is a negative test, we only need to do the test every five years. And I think the take-home message here for women who are pregnant is that we shouldn't worry so much about giving your baby cancer from you, what we should really worry about is making sure that we prevent cancer in the first place by having regular screening and, if eligible, making sure your boys and girls have vaccinations.

Norman Swan: Alison, thank you for joining us.

Alison Brand: Thank you.

Norman Swan: Dr Alison Brand is director of gynaecological oncology at Westmead Hospital in Sydney.

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Cancer gene sequencing and an unexpected transmission - Health Report - ABC News