Chemotherapy can significantly affect fertility, but the extent and permanence of this impact vary widely depending on several factors such as the type of chemotherapy drugs used, the dosage, the patient’s age, and whether radiation or surgery is also involved. Chemotherapy works by targeting rapidly dividing cells, which includes not only cancer cells but also healthy cells like those in the ovaries or testes responsible for producing eggs and sperm. Because of this, chemotherapy can damage or destroy these reproductive cells, leading to reduced fertility or even permanent infertility.
In women, chemotherapy can harm the ovarian reserve, which is the finite number of eggs a woman is born with. Unlike men, who continuously produce new sperm, women do not regenerate eggs, so damage to these cells can be permanent. Some chemotherapy drugs, especially alkylating agents such as cyclophosphamide, are particularly harmful to fertility. The damage can cause a temporary loss of menstrual cycles during treatment, but in some cases, menstruation and fertility may return months or years later. However, for others, chemotherapy can lead to premature ovarian failure or early menopause, meaning the ovaries stop functioning and no longer produce viable eggs. The younger a woman is at the time of treatment, the better her chances of recovering fertility, as younger ovaries tend to be more resilient.
In men, chemotherapy can reduce sperm production by damaging the cells in the testes that create sperm. This can result in a low sperm count or poor sperm quality, sometimes permanently. Radiation therapy near the testicles or brain can also disrupt hormone production that regulates sperm development, further affecting fertility. For boys treated with chemotherapy or radiation before or during puberty, there is a risk of delayed puberty or permanent infertility depending on the treatment intensity and location.
Radiation therapy, often used alongside chemotherapy, can compound fertility issues. Radiation directed at the pelvis can directly damage the ovaries, uterus, or testes. In women, pelvic radiation can cause scarring and reduce blood flow to the uterus, which may impair its ability to carry a pregnancy even if eggs remain viable. High doses of radiation can cause immediate ovarian failure, while lower doses might cause a gradual decline in fertility over time. Radiation to the brain can affect the hypothalamus or pituitary gland, which control hormone production critical for reproductive function, potentially disrupting menstrual cycles or sperm production.
The hypothalamic-pituitary-ovarian (HPO) axis in women is a key hormonal signaling pathway that controls menstruation and ovulation. Chemotherapy can disrupt this axis, causing menstrual cycles to stop temporarily or permanently. Younger women without prior ovulatory issues are more likely to regain normal cycles after treatment, but the longer and more intense the chemotherapy, the higher the chance that menstruation will not return. Hormone replacement therapy can sometimes help manage symptoms of early menopause induced by chemotherapy.
Because of these risks, fertility preservation strategies are often recommended before starting cancer treatment. These may include freezing eggs, embryos, or sperm to use later. Fertility preservation acts as a backup plan, especially important since cancer treatment and recovery can delay attempts to conceive, and fertility naturally declines with age. For women, retrieving eggs before chemotherapy yields the highest chance of preserving fertility. For men, sperm banking is a common approach.
Even when fertility returns after chemotherapy, pregnancies may require careful monitoring due to potential risks to the mother and baby. Some cancer treatments can increase the risk of complications such as miscarriage or premature birth. Additionally, oncologists usually advise waiting for a period after treatment before trying to conceive to ensure the patient’s health is stable and to avoid diagnostic conflicts during pregnancy.
In children treated with chemotherapy, fertility risks depend on their age, sex, and the treatment specifics. Younger children and those who have not yet gone through puberty may be more vulnerable to fertility damage. Boys face risks to sperm production, while girls may experience reduced ovarian reserve and menstrual irregularities. Radiation to the pelvis or brain can further increase thes