Presently, ovarian tissue freezing is still in a trial stage. Optimal indication, clinical efficacy, and technical conditions for freezing tissue are still being explored and changing.
The treatment is authorized by law in the regulation for biotechnology § 2–17 in Norway. The Womens' Clinic at Oslo University Hospital located at Rikshospitalet performs ovarian tissue freezing for Norway.
Thawing and reintroduction of tissue, and possibly in vitro fertilization, are possible techniques for reestablishing fertility after full remission of cancer. On a world basis, only a minority of births have been documented after reintroduction of ovarian tissue. Until now, it has not been relevant to reintroduce ovarian tissue for women in Norway who have stored tissue at Oslo University Hospital. Due to the experimental nature of the method, the patient must be well informed of the uncertainty surrounding the technique and the need for further method development.
The indication for ovarian tissue freezing is gonadotoxic treatment including chemotherapy and radiation therapy which lead to a high probability (> 50%) of sterility. The treating oncologist makes the final decision for the procedure.
Ovarian tissue freezing provides women who are treated for cancer the possibility of maintaining their fertility.
Examples of diagnoses where ovarian tissue freezing may be relevant:
- Cancer in pediatric and adolescent years:
- Cancer in women of reproductive age:
- breast cancer
- Benign hematological diseases, for example thalassemia or major aplastic anemia. Freezing of ovarian tissue is rarely indicated in other benign diseases.
Theoretically, there is no lower age limit for removing ovarian tissue, but an individual assessment must be done in each case.
- Age > 35 years
- HIV infection, hepatitis B, hepatitis C or syphilis
- Conditions which exclude a laparoscopic ovariectomy
- Treatment which prevents future pregnancy such as a hysterectomy or life-long treatment where pregnancy is contraindicated.
- Ovarial reserve is already lost due to, for example, previous chemotherapy or induction treatment. Previously completed chemotherapy with preserved ovarial reserve is not a contraindication.
- Disseminated systemic cancer is a relative contraindication. Risk of micrometastases in frozen tissue makes reintroduction of tissue in these cases inappropriate. In vitro fertilization of egg cells is a technique apparently several years into the future. These patients should therefore be well under 35 years.
- Maintain fertility in females £ 35 years undergoing treatment that will eradicate or strongly reduce fertility.