HEIDI STEVENS ,
Star tribune |
Freezing girls' reproductive tissues before their cancer treatments could enable them to bear children in adulthood. But the results are unclear.
For parents of young children diagnosed with cancer, looking ahead can be at once terrifying and consoling. Now, a burgeoning field of research allows those parents to consider their prepubescent child's ability to someday bear children -- and to take steps to protect that ability.
"Survival rates for pediatric cancers are higher than ever," says reproductive endocrinologist Dr. Jani Jensen, head of the fertility preservation program at Mayo Clinic in Rochester. "We hope their experience with this illness is a blip on the radar screen of a life that includes the things we all want, including the option to have children."
Of the estimated one in 500 children diagnosed with cancer per year, roughly 80 percent will be cured, according to the Women and Infants Hospital of Rhode Island, where a pediatric oncofertility team last year completed a fertility preservation treatment on a 17-month-old girl.
Because the aggressive methods necessary to treat certain types of cancers can cause infertility -- and because pediatric patients' bodies aren't physically prepared to bear children -- doctors are exploring fertility treatments that go beyond freezing eggs or freezing sperm.
"It's high-tech," Jensen says. "But it's a reality."
For prepubertal boys, options are "very limited," Jensen says. "Freezing pieces of testicular tissue is being done on an experimental basis."
For girls, the treatments are further along in the research process. Jared Robins, medical director of the program for fertility preservation at Women and Infants Hospital, says the procedure he performed on the 17-month-old Rhode Island girl last year is the most viable method.
"The current standard is autotransplantation, which is removing ovarian tissue before it's damaged, freezing it, and transplanting it back into the intended mother when she reaches child-bearing age," he says.
The tissue can be attached to a remaining ovary, another site in the pelvis, or even other sites in the body, Jensen says, with the idea that the pieces will regain their blood supply and possibly start remaking hormones or even spontaneously growing eggs. The procedure is performed by an obstetrician/gynecologist or physician with specific training in reproductive endocrinology and infertility. Another possibility, which Jensen describes as "in the works," is to remove the immature eggs from a patient's ovary and bring them to maturation in a laboratory setting.
"All the eggs a woman will ever have, she has by the time she's born," Robins explains. "The problem is that we're not very effective at taking early eggs and developing them outside the body into mature eggs that are able to achieve ovulation and ultimately become fertilized."