Breast Cancer and Fertility
As breast cancer survival rates improve, quality of life becomes increasingly important. For
young women diagnosed with breast cancer, a major concern on their minds may be what effect
the cancer or treatment will have on their fertility. The increasing use of chemotherapy for
breast cancer has implications in the physical and psychological state of women, so it is
important for women to know what risks and options they have.
The Biology of Female Fertility
Female germ cells (oocytes) give rise to the gamete (ovum/egg) that comes together with the
male gamete (sperm) during fertilization. The female germ cells proliferate before birth and stop
at a certain stage of the growth cycle. A female is born with about 1 million oocytes -- all the
eggs she will ever have in her life. By puberty the number has reduced to about 300,000 and
with each menstrual cycle there is further loss.
Chemo’s Effect on Fertility
Chemotherapy can cause temporary or permanent amenorrhea (lack of a menstrual period) due to
an increased loss of oocytes. If the number of viable cells falls below a critical number, ovarian
failure can occur. Essentially, a woman goes into early menopause and becomes unable to have
children anymore. Even if a woman continues having normal menstrual cycles after
chemotherapy, fertility may still be impaired and menopause may start earlier than it normally
would have. Women with breast cancer are less likely to get pregnant compared to other
women, but it is unclear whether this is due to direct effects, natural changes with advancing age,
or a change in attitude.
In general, chemotherapy for breast cancer appears to "age" reproductive function by about 10
Despite this, one nationwide study has shown that there is no direct risk of adverse birth
outcomes for women with breast cancer. This includes prematurity, low birth weight, stillbirth,
and congenital abnormalities. A history of breast cancer also does not mean that breastfeeding is
off limits, as there is no proof of increased risk of cancer in infants who are breastfed by mothers
with a history of or current breast cancer.
The risk of temporary or permanent menopause after chemo depends on several factors. Most
studied so far is the type and dose of drug used. As a general rule, alkylating agents are more
likely to induce amenorrhea than anthracyclines or antimetabolites. Studies show that the "CMF
regimen" (cyclophosphamide, methotrexate, and 5-fluorouracil) leads to amenorrhea in 21-71%
of women under 40 years of age; the rates are even higher in older women. However, this
combination is not commonly used anymore. Anthracycline-based chemotherapy regimens have
lower incidences of amenorrhea due to lower dose of cyclophosphamide.
It is important to remember that breast cancer doesn’t necessarily mean the end of the road.
There are options available for women who wish to protect their fertility before getting treatment
for breast cancer in case their fertility is affected by the chemotherapy. Among these options
include embryo cryopreservation and Luteinizing Hormone-Releasing Hormone (LHRH) agonist
to protect the ovaries. These methods are still being investigated, but they offer hope to young
women who wish to keep their options open.
Stephanie Wu BS, Shikha Jain MD
Jones AL. Fertility and pregnancy after breast cancer. The Breast. 2006;15(S2):S41-S46.
Hickey M et al. Breast cancer in young women and its impact on reproductive function. Human
Reproduction Update. 2009;15(3):323-339.
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