NIAGARA-ON-THE-LAKE, Ontario, Canada--A new technique is being
employed in an attempt to eventually restore the reproductive
potential of girls and young women receiving radiotherapy or
chemotherapy for cancer. Five families in a study from the United
Kingdom have chosen to have ovarian cortical tissue samples removed
and frozen prior to cancer therapy.
"With the increasing success in the treatment of childhood
leukemia and other cancers, we need to address the long-term
problems," Louise Bath, MD, Department of Child Life and Health,
University of Edinburgh, said at the 5th International Conference for
Long-Term Complications of Treatment of Children and Adolescents for
Cancer, hosted by Roswell Park Cancer Institute. "One of the
more distressing complications of cancer treatment is the potential
loss of fertility," she said.
A Study in Sheep
One method of preserving fertility is to harvest mature eggs from the
ovary prior to therapy. However, this option is not feasible for
prepubescent girls. A study in sheep showed that cryopreserved strips
of ovarian cortical tissue, which contain primordial follicles, could
be used to restore fertility.
Eight sheep underwent ovariectomy, and strips of their cortical
tissue were frozen. The tissue was later thawed and transplanted back
into the sheep. All eight had return of their estrous cycles, and one
even became pregnant due to a failed vasectomy on the part of the ram.
The selection criteria for women in the Edinburgh study are age less
than 30 years, no previous chemotherapy or radiotherapy, no existing
children, a greater than 50% chance of cancer cure, and a greater
than 50% risk of ovarian failure from the cancer treatment.
Seven families were approached for this tissue storage option. The
mean age of the patients was 12.4 years (range, 1.5 to 14.9 years),
and the cancers included Hodgkins disease, Ewings sarcoma,
extradural ependymoma of the lumbar region, and vaginal
rhabdomyosarcoma. Thus far, six families have given informed consent,
and five girls have undergone the procedure to save tissue samples.
Using a laparoscopic technique, 6 to 10 strips of ovarian cortex are
taken under direct visualization from one ovary. The tissue is
manipulated in an aseptic environment and stored in Leibovitz medium
with 10% DMSO and 10% autologous serum at less than -135°C in
the vapor phase of liquid nitrogen.
"There are multiple ethical issues to deal with when considering
the collection and storage of this tissue," Dr. Bath said.
Informed consent must be obtained, which includes consent for the
destruction of the tissue in the event of the childs death, and
the child has to undergo an additional surgical procedure to obtain
the tissue. "We make no guarantees that this technique will
restore fertility, and ultimately the re-implantation attempt will be
the patients decision to make, based upon future knowledge and
medical techniques," she said. "However, we believe that
there is potential to keep the tissue in a viable state for many
years, which offers hope to these girls."