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Thursday, 27 September, 2001, 00:47 GMT 01:47 UK
Ovary transplant safety fears eased
eggs
Researchers are hoping that mature eggs can be produced
Ovary tissue removed from cancer patients for transplantation back after treatment is unlikely to pose a threat to future health, say experts.

Chemotherapy can often harm a woman's ability to have a child afterwards, as it destroys cells in the ovaries.

"Ovary grafting" is seen as one way of getting round this, with the tissue taken out of harm's way until the treatment is over, then put back into the body again.


We can now be more optomistic about the application of ovarian cryopreservation and transplantation in cancer patients

Dr Samuel Kim, study leader
However, there had been fears that the untreated tissues could be harbouring cancer cells, and that putting them back into a cured patient would allow the disease to spread again.

To test this, research teams from Leeds and Manchester took ovary tissue from women who had been diagnosed with particularly aggressive forms of non-Hodgkin's lymphoma or Hodgkin's lymphoma.

This was transplanted into mice who had been treated so their natural immune defences were down.

As a comparison, a part of the each woman's lymphatic system - definitely containing cancer cells - was taken out and transplanted into other mice.

No cancers

None of the mice given ovarian transplants went on to develop new lymphoma cancers.

However, all of the mice given the other transplants did develop new cancers.

Doctors working on the project are encouraged by this, and suggest that this means the risks to women from ovary grafts are low.

Dr Samuel Kim, who led the study, said: "Ovarian tissue from cancer patients has been banked at many centres worldwide in preparation ultimately for transplantation back into patients after successful treatment.

"However, this step requires prior assurance that the tissue will not transmit disease after grafting.

"The study was based on worst-case scenarios of highly aggressive lymphomas that were likely to have already spread at the time the ovarian tissue was harvested."

He said: "We can now be more optomistic about the application of ovarian cryopreservation and transplantation in cancer patients, although these reassuring findings should not be interpreted as an absolute assurance of safety."

Difficult techniques

The team is now working on ways to decrease the risk by screening tissues prior to transplantation for any sign of malignancy.

The safety of ovarian grafts is just one hurdle with which scientists are grappling.

Harvesting, freezing and successfully thawing tissue is a highly technical challenge, but persuading it to start working again once replaced in the human body is also proving extremely difficult.

One UK patient is known to have menstruated following a graft, but the transplant only functioned for a couple of months.

The technique, once refined, would hopefully help pre-pubescent cancer patients, who are too young for eggs to be collected and frozen for later IVF use.

Doctors would also have to coax the immature egg follicles in their tissue to mature correctly before they could be used in fertility procedures.

See also:

27 Feb 01 | Health
Human ovaries 'grown in mice'
23 Sep 99 | Medical notes
Ovary grafting
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