Freezing Ovarian Tissue
Thirteen live births have occurred as the result of ovarian tissue preserved through cryopreservation and subsequent transplantation. The women who became mothers had their tissue frozen in advance of treatment for solid tumors and lymphoma. But this form of fertility preservation may not be safe for those who suffer from leukemia. This is according to recent research that was published in the online journal of the American Society of Hematology, called Blood.
Cryopreservation necessitates the removal of ovarian tissue which is then frozen. This is done before such patients undergo treatments such as radiation and chemotherapy. Once the cancer has been placed into remission, this tissue is then implanted back into the woman patient. However, physicians are concerned that leukemia patients run the risk that re-implanted tissues may contain malignant leukemia cells that could trigger a cancer recurrence.
Study author Marie-Madeleine Dolmans, MD, who is a professor at Brussels' Universite Catholique de Louvain said that the implanted tissue in those patients in remission for chronic and acute cases of leukemia bring a significant risk for returning cancer.
Fertility preservation is very important for young people with cancer. Acute lymphoblastic leukemia (ALL) tends to be diagnosed in the young. The National Cancer Institute says that most patients diagnosed with ALL, 71%, are under the age of 35. In chronic myelogenous leukemia (CML), 10% of these cases are in people under 35. Current estimates suggest that in 2010, 2,180 women will be diagnosed with ALL while 2,070 women will be diagnosed with CML.
Aggressive cancer therapies can damage reproductive organs. For this reason, the Belgian researchers decided to test the safety of ovarian tissue cryopreservation in leukemia patients. For the purposes of their study, the researchers chose to focus on 12 female ALL patients and 6 female CML patients. These 18 study participants were aged 2-31 years at the time they opted for ovarian tissue cryopreservation from 1999-2008.
While microscopic examination did not at first reveal the existence of cancerous cells in the ovarian tissue gathered from the patients, a technique known as real-time quantitative polymerase chain reaction (RT-qPCR) resulted in the discovery of cancerous cells in the ovarian tissue of 70% of the ALL patients along with another 33% of the tissue samples of the CML patients.
The researchers then grafted the tissue into 18 mice and observed them over a 6 month period. The mice that received ovarian tissue from the CML patients showed no signs of developing cancer cells, but four of the mice that received tissue from the ALL patients developed tumors.