How does cancer treatment affect fertility in women?

A lot of things must take place for a couple to make a baby, and a “system malfunction” at any point can lead to infertility. Cancer, or more often some cancer treatments, can interfere with some part of the process at almost any stage and affect your ability to have children.

Studies have suggested that women with cancer are less likely to be given information about preserving their fertility than men. If you are interested in having children in the future, you might need to be the one to start this conversation with your cancer team or your doctor.

Chemotherapy

Many chemotherapy (or chemo) drugs will damage some of the eggs stored in the ovaries. The effect will depend on the type and dose of chemo. It’s hard to predict how many women will be fertile after chemo since the woman’s age, the types of drugs she gets, and her drug dose all make a big difference. The drugs most likely to cause infertility are the alkylating drugs and nitrosoureas such as:

• Cyclophosphamide (Cytoxan^®)
• Ifosfamide (Ifex^®)
• Melphalan (Alkeran^®)
• Busulfan
• Procarbazine
• Chlorambucil (Leukeran^®)
• Carmustine (BCNU)
• Lomustine (CCNU)
• Mechlorethamine (Mustargen)

On the other hand, chemo drugs that have a low risk of causing infertility include:

• Methotrexate
• 5-fluorouracil (5-FU)
• Vincristine (Oncovin^®)
• Bleomycin
• Dactinomycin

Chemo and pregnancy

Age makes a difference: Women who are treated for cancer before they are 30 have the best chance of becoming pregnant after treatment. The good news is that young women who stop having menstrual periods during treatment often start having periods again after they are off chemo for a while.

After chemo, fertility may not last long: This means that even girls who had chemo before puberty (the time when periods begin and other body changes happen like growth of breasts and body hair) or young women whose menstrual periods start back after chemo are at some risk for early (premature) menopause. When a woman stops having periods long before the average age of 51, it’s considered premature menopause. She becomes infertile because her ovaries stop releasing eggs. Early menopause also means that the ovaries stop making the female hormones estrogen and progesterone.

Periods don’t always mean fertility: Even if a woman’s periods start back after cancer treatment has stopped, her fertility is still uncertain. Usually some eggs are destroyed by cancer treatment. You may need a fertility expert to help you find out if you are actually fertile.

Avoid getting pregnant during chemo: Many chemo drugs can hurt a developing fetus, causing birth defects or other harm. You might be fertile during some types of chemo, so you will need to use very effective birth control. Talk with your doctor about this.

It can harm the baby if you get pregnant too soon after chemo: Women are often advised not to get pregnant within the first 6 months after chemo because the medicine may have damaged the eggs that were maturing during treatment. If a damaged egg is fertilized, the embryo could miscarry or develop into a baby with a genetic problem. Studies about this are hard to find.

Bone marrow or stem cell transplant

Bone marrow or stem cell transplant usually involves high doses of chemo and sometimes radiation before the transplant. This often permanently stops a woman from releasing eggs. Talk with your doctor or nurse about this risk before starting treatment. (See the sections called “Chemotherapy” and “Radiation treatments” for more on these parts of the transplant.)

Radiation treatments

Radiation therapy uses high-energy rays to kill cancer cells. These rays can also damage a woman’s ovaries. For a woman having radiation therapy to the abdomen (belly) or pelvis, the amount of radiation absorbed by the ovaries will determine if she will become infertile. High doses can destroy all the eggs in the ovaries and cause early menopause. Even if the radiation is not aimed right at the ovaries, the rays bounce around inside the body and can still damage the ovaries. When radiation is directed inside the vagina, the ovaries absorb a high dose of radiation. Radiation to the uterus can increase the risk of miscarriage, low-birth weight infants, and premature births. This happens because the treatment can cause scarring which restricts flexibility and blood flow to the uterus. These problems also can interfere with the growth and expansion of the uterus during pregnancy.

Sometimes radiation to the brain may affect the pituitary gland. The pituitary gland signals the ovaries to make hormones. Interference with these signals can affect egg production. This may or may not affect fertility depending on the focus and dose of the radiation.

You may be fertile when you start getting radiation treatments, but it’s important to avoid pregnancy until after treatment is completed. Talk with your doctor about this.

Surgery

Surgery on certain parts of the reproductive system can cause infertility. For some cancers in women, a hysterectomy is part of the treatment. A hysterectomy is surgery to remove the uterus either through the vagina or through a cut made in the abdomen (belly). Once the uterus is removed, a woman cannot carry a child. The ovaries might be removed (called an oophorectomy) at the same time the uterus is taken out. Without ovaries, a woman can’t get pregnant because she no longer has any eggs. In some women with early stage ovarian or cervical cancer, the surgeon will try to save one ovary, if possible, to preserve eggs. Keeping at least one ovary also preserves the hormones that prevent menopause symptoms like hot flashes and vaginal dryness. Some women with small cervical cancers can have a surgery called a trachelectomy, which removes the cervix but leaves the uterus behind so a woman can carry a pregnancy. (See “Radical trachelectomy” under the section called “Preserving fertility in women before cancer treatment.”)

Sometimes surgery can cause scarring in the fallopian tubes. These scars may block the tubes and prevent eggs from traveling to meet the sperm. This means they can’t become fertilized and move on to the uterus to implant in the lining.

Other treatments

Hormone therapies used to treat breast cancer or other cancers can affect your ability to have a child. The effect of some of the newer treatments on fertility and pregnancy, like vaccines, immune therapies, or biological response modifiers, is not yet known. It’s always best to talk to your doctor, nurse, or other member of your health care team about your treatment and any possible effects on your sexual function and fertility.