Post-Cancer Fertility Treatment

Fertility hope for cancer patients

Doctors have grown the world's first embryo from frozen human ovary tissue, raising the strongest hopes yet that the technique could be used to restore fertility in cancer patients whose treatment would otherwise damage the ovaries irreparably.

The patient was aged 30 and newly diagnosed with breast cancer when the tissue from the ovary was frozen, and 36 when it was replaced into her abdomen. Within three months the transplanted tissue began producing eggs again. An egg was harvested after stimulation with IVF drugs and mixed with her partner's sperm to create the embryo, said Kutluk Oktay in the medical journal The Lancet.

Although the embryo did not result in pregnancy, its creation represents a big step in the quest to refine the technique, which has previously been successful only in animals.

This is certain to be welcome news to young women who are cancer patients. I'm not so sure it's a good thing.

Breast cancer, leukaemia and lymphomas such as Hodgkin's disease were among the cancers that affected young women who might benefit from the freezing technique, Dr Boyle said.

Many cancers and other diseases of the young have an inherited basis. In the natural scheme of things, the incidence of inherited cancers was kept in check by high mortality rates, and in modern times, treatments that rendered the patient infertile - a devastating loss for the individual, but a genetic "safety valve" for the population. Natural selection is not pretty, nor is it kind - but it's necessary if gene frequencies are to be kept under control. Also, many of these cancer predispositions are inherited as autosomal dominants - meaning that high numbers of the children of these patients could face the prospect of suffering from it as well.

Eugenics? Not quite - questioning the wisdom of cheating the Darwinian system has nothing to do with race "purification", but with the realities of population genetics and gene frequencies. When you interfere with natural selection against disease genes, gene frequencies for those disorders do not remain static - they rise.

As dog breeders, we face constant challenges to control genetic disorders in our breeding programs - ocular, heart, kidney problems, diseases of the blood - and cancer. But they are not evenly distributed. For example, 25% of all female Boxers will develop mammary cancer, and bone cancers will take high percentages of Poodles and Dobermans. In contrast, my own breed is rarely affected with early onset cancers, but autoimmune disease and immunocompromised dogs are serious problems in some lines.

While the goals and methods in breeding purebred animals are light years away from those of human families - the rules that govern them at the chromosomal level are exactly the same. With dog breeding, we have an advantage that human medicine has lost with specialization. We get to see the "big picture".

Oncologists are charged with restoring the health of their patients and extending their lives. They are not usually concerned with genetic counselling. Fertility specialists specialize in producing children - this is their measure of success. Those children will not return to the office later in life for treatment of BRCA1 breast or ovarian cancer. They may be retired before most of their success stories are ready to have children of their own.

In dog breeding, the cycle is much shorter - generations turn over every 2 years, instead of every 20. We often have 4 or more generations in a household at the same time, and they age more quickly. We witness how breeding from animals of questionable health and longevity impacts that of later generations - and that it does so exponentially.

I know it's a comparison that will make some people uneasy, or even angry. But it's hard not to take a long view when you read about "advancements" in treating human infertility, and wonder if they really understand what it is they're doing.

Posted by Kate at March 9, 2004 11:50 AM