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Breast cancer during pregnancy isn't common. But if you find a lump or notice any changes in your breasts that concern you, tell your doctor or nurse right away. There are a variety of tests a pregnant woman can have if breast cancer is suspected. And there are options for treating breast cancer if you are pregnant.
If you are pregnant and breast cancer is found, it may be called gestational breast cancer or pregnancy-associated breast cancer (PABC).
Breast cancer is found in about 1 in every 3,000 pregnant women. It is the most common type of cancer found during pregnancy.
Changes in hormone levels during pregnancy cause the breasts to change. The breasts may become larger, lumpy, and/or tender. This can make it harder for you or your doctor to notice a lump caused by cancer until it gets quite large.
Another reason it may be hard to find breast cancers early during pregnancy is that many women put off breast cancer screening with mammograms until after the pregnancy. Even when women do get mammograms, pregnancy and breastfeeding can make breast tissue denser, which can make it harder to see an early cancer on a mammogram.
Because of these challenges, when a pregnant woman develops breast cancer, it’s often diagnosed at a later stage than it usually is in women who are not pregnant. For example, it’s more likely to have already spread to lymph nodes.
If you find a lump or other changes in your breasts that concern you, don’t ignore them. Tell your doctor or nurse right away. Any suspicious breast changes should be checked out or even biopsied (see below) before assuming they are a normal response to pregnancy.
Along with a clinical breast exam, several types of imaging tests can be used to look for breast abnormalities, if needed. Typically a breast ultrasound and/or mammogram can be done. A breast biopsy (removing a piece of the abnormal area to check it for cancer cells) is often another option, especially if imaging tests show a suspicious finding. (See below.)
A main concern with any imaging test during pregnancy is whether it exposes the developing fetus to radiation, which could be harmful, especially during the first trimester.
Mammograms can find most breast cancers that start when a woman is pregnant, and it’s generally thought to be safe to have a mammogram during pregnancy. The amount of radiation needed for a mammogram is small, and the radiation is focused on the breasts, so most of it doesn’t reach other parts of the body. For extra protection, a lead shield is placed over the lower part of the belly to help keep radiation from reaching the womb. Still, small amounts of radiation might reach the fetus, and scientists can’t be certain about the effects of even a very small dose of radiation on an unborn baby.
Ultrasound exams of the breast do not use radiation and are thought to be safe during pregnancy. This is typically an easy test to have, so it’s often the first test used to evaluate a change in the breast (such as a lump) during pregnancy.
Other tests, such as PET scans, bone scans, and computed tomography (CT) scans are more likely to expose the fetus to radiation (see below).
Magnetic resonance imaging (MRI) does not use radiation. However, breast MRIs typically require that a contrast material called gadolinium is injected into the blood in order to get useful images. This contrast can cross the placenta (the organ that connects the mother to the fetus) and has been linked with fetal abnormalities in lab animals. Because of this, doctors typically don’t recommend breast MRI during pregnancy.
If a new breast lump or abnormal imaging test result raises concerns about a breast change possibly being cancer, a biopsy is typically done. During a biopsy, small pieces of breast tissue are taken from the area of concern.
The most common breast biopsy technique is a core needle biopsy, which uses a hollow needle to remove the pieces of breast tissue. This is usually done as an outpatient procedure, even if you’re pregnant. Most often, numbing medicine (local anesthesia) is used to numb just the area of the breast where the biopsy will be done. This causes little risk to the fetus.
If a core needle biopsy doesn’t give a clear answer, a surgical biopsy is typically the next step. For this type of biopsy, a larger piece of breast tissue is removed through a small cut (incision) in the breast. Surgical biopsies are often done under general anesthesia (where you are given medicine to put you into a deep sleep), which carries a small risk to the fetus.
If breast cancer is found, you might need other tests to find out if cancer cells have spread within the breast or to other parts of the body. This process is called staging. Different staging tests may be needed, depending on your situation.
As noted above, ultrasound scans do not use radiation and are safe during pregnancy.
Chest x-rays are sometimes needed to help make treatment decisions. They use a small amount of radiation to create the images. They’re generally thought to be safe to have when you’re pregnant, as long as your belly is shielded.
Other tests, such as PET scans, bone scans, and computed tomography (CT) scans are more likely to expose the fetus to radiation. These tests are not often needed to stage breast cancer, especially if the cancer is thought to be just in the breast. If one of these tests is needed, doctors might be able to make adjustments to limit the amount of radiation exposure to the fetus.
The treatment of breast cancer in pregnant women is typically similar to that used for non-pregnant women, especially for early-stage disease, although some adjustments might be needed to help protect the fetus. Learn more in Treating Breast Cancer During Pregnancy.
Breast cancer has never been found to spread from the mother to the fetus. But in a few rare cases, the cancer has reached the placenta (the organ that connects the mother to the fetus). This could affect the amount of nutrition the fetus gets from the mother.
For answers to some common questions about pregnancy after having had breast cancer, see Pregnancy After Breast Cancer.
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.
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Last Revised: January 14, 2022