OVARIAN CRYOPRESERVATION NOT SAFE FOR HEMATOLOGICAL MALIGNACIES

August 19, 2010 — Ovarian tissue cryopreservation is a relatively new option for cancer patients who wish to preserve fertility prior to undergoing chemotherapy and radiotherapy. But even though autotransplantation of frozen–thawed ovarian tissue harvested before chemotherapy/radiotherapy has thus far led to 13 live births, a serious risk might accompany this procedure.

In a report published online July 1 in Blood, researchers believe that this method of fertility preservation might be unsafe for patients with leukemia. The risk is that the reimplanted tissue might harbor malignant cells that could induce disease recurrence.

When investigating cryopreserved ovarian tissue from 6 patients with chronic myeloid leukemia (CML) and 12 with acute lymphoblastic leukemia (ALL), standard histology did not reveal any malignant cells. However, with quantitative PCR, the researchers found positive leukemic markers in the ovarian tissue of 70% of the ALL patients and of 33% of the CML patients.

For further analysis, ovarian tissue from the 18 patients was grafted into mice for an observational period of 6 months. All of the mice grafted with ovarian tissue from the CML patients stayed healthy, but 4 grafted with ovarian tissue from the ALL patients developed intraperitoneal leukemic masses.

In 3 of the 4 mice that developed leukemic masses, the authors note, the ovarian tissue used for grafting had been positive on PCR for leukemic markers. However, in the fourth mouse, no molecular markers had been found.

"Given our findings, further research is needed to develop safer options for fertility preservation in patients with acute and chronic leukemias," said study author Jacques Donnez, MD, professor at the Université catholique de Louvain in Brussels, Belgium, in a statement.

Promising Option But Risky in Leukemia

Advances in cancer treatment, such as aggressive chemotherapy and radiotherapy, and bone marrow transplantation have greatly increased the life expectancy of young female cancer patients, the authors note. However, these therapies generally lead to a loss of both endocrine and reproductive functions, resulting in premature menopause and infertility.

Currently, several options exist for young women interested in preserving their fertility prior to undergoing treatment: in vitro fertilization (IVF) with embryo cryopreservation, oocyte cryopreservation, and ovarian tissue cryopreservation. The authors point out that IVF procedures with embryo cryopreservation or mature oocyte cryopreservation are only applicable if chemotherapy can be delayed.

Another option, immature oocyte retrieval in the luteal phase followed by in vitro maturation, has been proposed. But no pregnancies to date have been reported using this technique in cancer patients.

Thus, for patients unable to delay chemotherapy and for prepubertal patients, cryopreservation of ovarian tissue remains the main option.

Dr. Donnez colleagues note that in their department, 44% of all malignant indications for ovarian tissue cryopreservation are hematologic malignancies, such as Hodgkin's lymphoma (22%), leukemia (11.3%), and non-Hodgkin's lymphoma (11%).

But a major concern is that the frozen–thawed ovarian tissue might be contaminated with malignant cells, and might induce a recurrence of the disease after reimplantation. In the case of leukemia, they write, the malignant cells might be present in the bloodstream and at risk of being transferred.

Safety Seen in Other Cancers

The results seen in this study were not unexpected, said Claus Yding Andersen, DMSc, from the Laboratory of Reproductive Biology and The Fertility Clinic, Copenhagen University Hospital, Denmark.

In an interview with Medscape Medical News, Dr. Andersen explained that his group recently completed their own study and came to the same conclusions.

"We saw the same results, and we could find traces of malignant tissue," he said. "So for now, ovarian cryopreservation is not recommended for leukemia patients."

In the study by Dr. Andersen's group — which is currently in press (Fertil Steril. DOI:10.1016/j.fertnstert.2009.11.032) — histology and immunohistochemistry did not reveal leukemic cell infiltration in the ovarian tissue in any of the 26 study participants. However, in the majority of cases where it was possible to use PCR, evidence of leukemic cells was detected in the ovarian tissue.

The procedure appears to be safe, thus far, for patients with other cancers, including breast cancer and Hodgkin's lymphoma, Dr. Andersen pointed out. "We haven't had any reports yet of recurrences caused by autotransplantation, and 1 breast cancer patient has been followed for several years."

"Right now it appears that using this technique in breast cancer patients is safe, but we really need to do more studies to make sure of that," he added. "Patients with Hodgkin's lymphoma have received the most transplants; none have relapsed and there [have been] no signs of cancer cell infiltration."

None of the autotransplantations performed to date appear to have caused a reintroduction of the original disease, Dr. Andersen said. However, in the study by Dr. Donnez and colleagues, the cells proved to be viable in a mouse model and caused disease, indicating that the presence of leukemic cells in the ovarian tissue might cause a relapse in humans.

Dr. Andersen pointed out that all of these patients are at risk for relapse, as is the case with cancer in general. "Whether their disease relapse is caused by the transplant or other factors is something that we just don't know," he said.

Clear Evidence of Ovarian Contamination

The study by Dr. Donnez and colleagues involved patients who were between the ages of 2 and 31 years at the time their ovarian tissue was cryopreserved (from 1999 to 2008). The mean age of patients with ALL was 14.5 years and with CML was 24.7 years.

All of the CML patients were carriers of the BCR–ABL1 gene; the ALL patients were carriers of various mutations, reciprocal chromosomal translocations, hyperdiploidy, or hypodiploidy. In 2 of the ALL patients, the authors note that they were unable to detect any molecular markers of disease and, therefore, molecular genetic analysis could not be conducted on their ovarian tissue.

Among the 6 CML patients, the ovarian tissue of 2 was found to be positive for the BCR–ABL leukemic marker. All of the CML patients had been treated with hydroxycarbamide, with or without imatinib, prior to referral for ovarian tissue cryopreservation.

Similarly, the ovarian tissue of 7 of the 10 ALL patients (2 were excluded from PCR analysis) had positive markers. The analysis showed that the tissue from 1 patient was positive for the BCR–ABL fusion gene, from 1 patient for t(1;19)(q23;p23.3), and from the remaining 5 patients for immunoglobulins and/or TCRγ rearrangement genes.

The authors point out that the 3 ALL patients whose ovarian tissue was negative for immunoglobulins and/or TCRγ rearrangement genes had received chemotherapy prior to ovarian tissue cryopreservation.

Among the remaining 7 patients, all of whom had ovarian tissue that was positive for ALL markers, 4 had not received any treatment prior to ovarian tissue cryopreservation, and the other 3 had undergone 1 regimen of chemotherapy.

The results of this study provide "clear evidence" of ovarian contamination by leukemic cells in both ALL and CML patients, and show that human ovarian tissue positive for ALL markers on PCR can transmit the disease in an animal model, the authors conclude.

The data also show that "chemotherapy before ovarian cryopreservation does not exclude malignant contamination," and that "reimplantation of cryopreserved ovarian tissue from patients with ALL puts them at risk of disease recurrence," they write.

All authors have disclosed no relevant financial relationships.

Blood. Published online July 1, 2010. Abstract