Chemotherapy is a powerful, life-saving treatment for childhood cancers. While its primary goal is to eradicate cancerous cells, a significant concern for patients and families is its potential impact on future fertility. Understanding this side effect is important for those navigating cancer treatment and its long-term implications.
How Chemotherapy Affects Reproductive Organs
Chemotherapy drugs target and destroy rapidly dividing cells, including healthy reproductive cells. In females, chemotherapy can damage the ovaries, which contain a finite number of oocytes (egg cells). This damage can reduce both the quantity and quality of eggs, potentially leading to primary ovarian insufficiency (POI), where ovaries stop functioning properly. Some agents induce DNA breaks within oocytes, which can lead to the loss of primordial follicles.
For males, chemotherapy affects the testes, responsible for producing sperm and testosterone. These drugs can harm spermatogonia, the cells that continuously produce new sperm. Damage to these sperm-producing cells can result in reduced sperm count or even azoospermia (complete absence of sperm). While some damage might be temporary, leading to recovery, permanent impairment is also possible.
Factors That Influence Fertility Risk
The likelihood and severity of fertility impairment depend on several factors. The specific type of chemotherapy drugs used is a primary determinant, with alkylating agents posing a high risk. These drugs are known for their gonadotoxic effects, meaning they are toxic to reproductive organs.
The cumulative dose and duration of treatment also play a crucial role; higher doses and longer periods increase the risk of permanent fertility damage. A child’s age at treatment influences susceptibility, as pre-pubertal ovaries may exhibit some resistance compared to post-pubertal ovaries. However, recent research suggests that even in pre-pubertal boys, chemotherapy can have a greater effect on the testes than previously assumed, impacting future sperm count.
Sex differences also exist. Females have a fixed supply of eggs, making them vulnerable to depletion, while males continuously produce sperm, potentially allowing for recovery. Combination therapies, multiple chemotherapy drugs or chemotherapy combined with radiation, can further elevate the risk of permanent infertility.
Options for Fertility Preservation
Several strategies exist to preserve future fertility for individuals undergoing childhood cancer treatment, though their applicability depends on age and pubertal status. For post-pubertal boys, sperm banking is a well-established and effective method where samples are collected and frozen before treatment. This is considered the gold standard for male fertility preservation.
For pre-pubertal boys who do not produce mature sperm, testicular tissue cryopreservation is an experimental option. This procedure involves surgically removing and freezing a small piece of testicular tissue containing spermatogonial stem cells, with the hope of using these cells to restore fertility. While promising, techniques to generate viable sperm from this tissue are still under development.
Post-pubertal girls have options like oocyte (egg) cryopreservation or embryo cryopreservation. Egg freezing involves stimulating the ovaries to produce multiple eggs, which are then retrieved and frozen. Embryo cryopreservation follows a similar process, but eggs are fertilized with sperm before freezing. Both methods require ovarian stimulation, which may delay cancer treatment.
Ovarian tissue cryopreservation is the only available fertility preservation option for pre-pubertal girls, as it does not require hormonal stimulation. This minimally invasive procedure involves removing and freezing a portion of ovarian cortical tissue, which contains immature eggs. After cancer treatment, the tissue can be reimplanted to restore ovarian function.
Managing Infertility After Treatment
Facing infertility after childhood cancer treatment can be challenging for survivors. The focus during active treatment is often on survival, and the long-term impact on fertility may only become apparent years later. Assisted reproductive technologies (ART) may offer pathways to parenthood.
In vitro fertilization (IVF) using previously preserved gametes (eggs or sperm) is a common ART approach. If gametes were not preserved or are not viable, other options include donor sperm or donor eggs, or gestational surrogacy. Adoption also provides a path to building a family for many cancer survivors.