The side effects of chemotherapy depend mainly on the drugs the patient receives. Like other types of breast cancer treatment, side effects vary from person to person.
In general, anticancer drugs affect rapidly dividing cells. These include blood cells, which fight infection, cause the blood to clot, and carry oxygen to all parts of the body. When blood cells are affected by anticancer drugs, patients are more likely to get infections, bruise or bleed easily, and may have less energy during treatment and for some time afterward. Cells in hair follicles and cells that line the digestive tract also divide rapidly. As a result of chemotherapy, some patients may lose their hair and may have other side effects, such as loss of appetite, nausea, vomiting, diarrhea, or mouth sores.
Fortunately, many of these chemotherapy side effects can now be controlled, thanks to improvements in drugs that are used to reduce or prevent vomiting, called antiemetics and other medications. Side effects generally do not last long, and gradually disappear during the recovery phase of the chemotherapy cycle or after the treatment is completed.
With modern chemotherapy, long-term side effects are quite rare. However, there have been cases where the heart is weakened, and second cancers such as leukemia have developed. Also, some anticancer drugs can damage a woman’s ovaries. If the ovaries fail to produce hormones, the woman may have symptoms of menopause, such as hot flashes and vaginal dryness. Her periods may become irregular or stop, and she may not be able to become pregnant. However, some women may still be able to get pregnant during treatment. Because the effects of chemotherapy on an unborn child are not known, it is important for a woman to talk to her provider about birth control before treatment begins. After treatment, some women regain their ability to become pregnant, but in women over the age of 35 or 40, infertility is likely to be permanent.