Canadian doctors have reported a new method for preserving the fertility of women undergoing cancer treatment, which they say offers an alternative to embryo and ovarian tissue freezing. In a recent letter to the Lancet medical journal, the team describe the removal of immature eggs from the ovaries of young cancer patients, which are then matured in the laboratory. The technique has so far proved successful for eight women, say the scientists, who are based at the McGill University Health Center in Montreal.
Currently, women about to undergo cancer treatment that could leave them sterile are able to use IVF followed by freezing of the resulting embryos. However, this option is only open to patients with a partner, and even then is not always possible, according to team leader Seang-Lin Tan. 'There is often inadequate time to undertake an IVF cycle before starting chemotherapy and the IVF fertility drugs should not be used for some cancers', he explained.
The doctors wrote to the Lancet in response to a recent report by a US team, which described the world's first viable human embryo created using frozen, thawed ovarian tissue. But although a baby monkey has been born using this approach, the technique has yet to lead to a pregnancy in humans. In their letter, the Canadian doctors say they have carried out ovarian tissue freezing for 'at least a dozen patients', but add that 'more knowledge and evidence is needed' before the procedure becomes routine clinical practice.
The letter cites the case of a 33-year old woman diagnosed with breast cancer, who was about to start chemotherapy. The doctors collected a total of 30 immature eggs, without using hormone stimulation, and managed to freeze 17 matured eggs. 'Our technique does not involve hormone therapy or surgery. Women with cancer should be offered immature egg collection and egg or embryo freezing to preserve their fertility before they commence their cancer treatment', concludes Tan.