Having breast cancer during pregnancy is very rare. But more and more women are choosing to have children later in life, and the risk of breast cancer goes up as women get older. Because of this, doctors expect there will be more cases of breast cancer during pregnancy in the future.

Breast cancer is found in about 1 in every 3,000 pregnant women. Breast cancer is the most common type of cancer found during pregnancy, while breastfeeding, or within the first year of delivery. You may hear this called gestational breast cancer or pregnancy-associated breast cancer (PABC). The special concerns of breast cancer during pregnancy are reviewed here.

Finding breast cancer during pregnancy

When a pregnant woman develops breast cancer, it’s often diagnosed at a later stage than it would be if the woman were not pregnant. It’s also more likely to have spread to the lymph nodes. This is partly because hormone changes during pregnancy. Pregnancy stops monthly menstrual cycles and the levels of estrogen and progesterone go up. Prolactin, a hormone that tells the breasts to prepare for nursing, also goes up during pregnancy. These hormone changes cause the breasts to change. They may become larger, lumpy, and tender. This can make it harder for the woman or her 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 screening for breast cancer is often delayed until after the pregnancy is over. Pregnancy and breast feeding can also make breast tissue denser. This can make it harder to see an early cancer on a mammogram. Also, the early changes caused by cancer can be easily mistaken for the normal changes that happen with pregnancy. Delayed diagnosis remains one of the biggest problems with breast cancer in pregnancy.

If you find a lump or notice any changes in your breasts, take it seriously. If your doctor doesn’t want to check it out with tests such as a mammogram, ask about other kinds of imaging tests such as ultrasound or MRI. You may need to get a second opinion. Any suspicious breast changes should be checked out or even biopsied before assuming they are a normal response to pregnancy.

Mammograms can find most breast cancers that start when a woman is pregnant, and it’s thought to be fairly 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 that most of it does not reach other parts of the body. For extra protection, a lead shield is placed over the lower part of the belly to stop radiation from reaching the womb. Still, scientists can’t be certain about the effects of even a very small dose of radiation on an unborn baby.

Even during pregnancy, early detection is an important part of breast health. Talk to your doctor or nurse about breast exams and the best time for your next mammogram. As always, if you find a lump or change in your breasts, tell your doctor or nurse right away.

Breast cancer diagnosis and staging during pregnancy

Breast biopsy during pregnancy

A new lump or abnormal imaging test result may cause concern, but a biopsy is needed to find out if a breast change is cancer. During a biopsy a piece of tissue is taken from the area of concern. Breast biopsies are most often done using a needle. This is usually done as an outpatient procedure (even on a pregnant woman). The doctor uses medicine to numb just the area of the breast involved in the biopsy. This causes little risk to the fetus.

If a needle biopsy doesn’t provide an answer, a surgical biopsy is the next step. This means removing a piece of tissue through a small cut (incision) in the breast. Surgical biopsies are often done under general anesthesia (where drugs are used to put the patient into a deep sleep), which carries a small risk to the fetus.

You can get more details on different types of breast biopsies in our document called For Women Facing a Breast Biopsy.

Tests to learn the stage of the breast cancer

If breast cancer is found, other tests may be needed to find out if cancer cells have spread within the breast or to other parts of the body. This process is called staging. Staging is very important for pregnant women with breast cancer because their cancers tend to be found at a more advanced stage (the tumor is likely to be bigger and to have spread beyond the breast). Which staging tests may be needed depends on your case.

Keep in mind that tests like ultrasound and magnetic resonance imaging (MRI) scans do not expose the fetus to radiation. Overall, these tests are thought to be safe and can be used if they are important to your care. But the contrast material (dye) sometimes used in MRI crosses the placenta, the organ that connects the mother to the fetus. It has been linked with fetal abnormalities in lab animals. For this reason, an MRI with contrast dye is not recommended during pregnancy. But an MRI without contrast can be used if needed.

Chest x-rays are sometimes needed to help make treatment decisions. They use a small amount of radiation. They are thought to be safe for pregnant women when the 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, especially if the cancer is thought to be just in the breast. For some of these tests, doctors may be able to adjust the way the test is done to limit the amount of radiation the fetus is exposed to if the tests musts be done.

In very few 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, but there are no reported cases of breast cancer being transferred from the mother to the fetus.

Breast cancer treatment during pregnancy

If breast cancer is found during pregnancy, the treatment recommendations depend on things such as:

• The size of the tumor
• Where the tumor is
• If the cancer has spread and if it has, how far
• How far along the pregnancy is
• What the woman prefers

Treating a pregnant woman with breast cancer has the same goal as treating a non-pregnant woman: control the cancer and keep it from spreading. But the extra concern of protecting a growing fetus may make reaching these goals more complex.

Surgery for breast cancer is generally safe in pregnancy. Other treatments for breast cancer, such as chemotherapy, hormone therapy, targeted therapy, and radiation can harm the fetus if given during pregnancy. Although chemotherapy seems to be safe for the fetus if given later in pregnancy, it isn’t safe early on. If a women has breast cancer in early pregnancy and needs chemotherapy right away, she may be asked to think about ending the pregnancy. For some breast cancers, such as inflammatory breast cancer, a delay in treatment would likely harm the patient.

Older studies reportedly found that ending a pregnancy in order to have cancer treatment didn’t improve a woman’s prognosis (outlook). (See the section “Survival rates after breast cancer during pregnancy” for further discussion on this.) Even though there were flaws in these studies, ending the pregnancy is no longer routinely recommended when breast cancer is found. Still, this option may be discussed when looking at all the treatment choices available, especially in aggressive cancers that may need immediate treatment. Women and their families need to fully understand the risks and benefits of all their options before making treatment decisions.

Surgery

Surgery to remove the cancer in the breast and nearby lymph nodes is generally safe in pregnancy. This is a major part of treatment for any woman with early breast cancer, including women who are pregnant. For many cancers, either removing the entire breast (mastectomy) or just the part containing the cancer (breast-conserving surgery - BCS) is an option. Mastectomy is used more often for pregnant women with breast cancer because women who have breast-conserving surgery need radiation therapy afterward.

Radiation could affect the fetus if it is given during the pregnancy, so it can’t be given until after delivery, and delaying radiation too long could increase the chance of the cancer coming back. Cancer that’s found in the third trimester may mean very little delay in radiation treatments, so there would probably be no effect on outcome. And radiation is normally given after chemotherapy (chemo), so a woman who will be getting chemo after surgery may have little or no delay in her radiation treatments. But cancers found early in the pregnancy may mean a longer delay in starting radiation. These cancers often need to be treated with mastectomy.

In addition to removing the tumor in the breast, one or more lymph nodes in the armpit also need to be removed to check for cancer spread. One way to do this is an axillary lymph node dissection. This removes many of the lymph nodes under the arm. Another procedure, called a sentinel lymph node biopsy (SNLB), might be an option depending on the how far along you are in pregnancy and your cancer stage. This procedure uses tracers and dye to pinpoint the nodes most likely to contain cancer cells. SNLB allows the doctor to remove fewer nodes. But there are concerns about the effects the radioactive tracer and blue dyes that are used for SNLB might have on the fetus. Because of these concerns, some experts recommend that SLNB only be used later in pregnancy.

Anesthesia

Surgery for breast cancer generally carries little risk to the fetus. But there are certain times in pregnancy when anesthesia (the drugs used to make you sleep for surgery) may be riskier for the fetus.

Many doctors, such as a high-risk obstetrician, a surgeon, and an anesthesiologist will need to work together to decide the best time during pregnancy to do surgery. If the surgery is done later in the pregnancy, the obstetrician may be there just in case there are any problems with the baby during surgery. Together, these doctors will decide which drugs and techniques are the safest for both the mother and the baby.

Treatment after surgery

Depending on the cancer’s stage, a woman may get more treatment such as chemotherapy, radiation, and/or hormone therapy after surgery to help lower the risk of the cancer coming back. This is called adjuvant treatment. In some cases, this treatment can be put off until after delivery.

More information about the kinds of surgery used to treat breast cancer can be found in our document Breast Cancer.

Chemotherapy

Chemotherapy, which is also called chemo, may be used along with surgery (as an adjuvant treatment) for some earlier stages of breast cancer. It also may be used by itself for more advanced cancers.

Chemo is not given during the first 3 months of pregnancy (the first trimester). Because most of the baby’s internal organs develop during this time, the safety of chemo hasn’t been studied in the first trimester. The risk of miscarriage (losing the baby) is also the greatest during this time.

For many years, it was thought that all chemo would harm an unborn baby no matter when it was given. But studies have shown that certain chemo drugs used during the second and third trimesters (months 4 through 9 of pregnancy) don’t raise the risk of birth defects, stillbirths, or health problems shortly after birth, though they may increase the risk of early delivery. Researchers still don’t know if these children will have any long-term effects.

When a pregnant woman with early breast cancer needs chemo after surgery (adjuvant chemo), it’s usually delayed until at least the second trimester. If a woman is already in her third trimester when the cancer is found, the chemo may be delayed until after birth. The birth may be induced (brought on) a few weeks early in some cases. These same treatment plans may also be used for women with more advanced cancer.

Chemo should not be given after 35 weeks of pregnancy or within 3 weeks of delivery because it can lower the mother’s blood counts. This could cause bleeding and increase the chances of infection during birth. Holding off on chemo for the last few weeks before delivery allows the mother’s blood counts to return to normal before childbirth.

Radiation therapy

Radiation therapy to the breast is often used after breast-conserving surgeries (lumpectomy or partial mastectomy) to help reduce the risk of the cancer coming back. The high doses of radiation used for this can harm the fetus any time during pregnancy. It may cause miscarriage, birth defects, slow fetal growth, or a higher risk of childhood cancer. Because of this, doctors don’t use radiation treatment during pregnancy.

Pregnant women who choose lumpectomy or partial mastectomy may be able to have surgery during pregnancy and then wait until after the baby is born to get radiation therapy. But this treatment approach has not been well-studied. Waiting too long to start radiation can increase the chance of the cancer coming back.

Hormone therapy

Hormone therapy is often used as adjuvant treatment after surgery or as treatment for advanced breast cancer in women with hormone receptor positive breast cancer. Drugs used for hormone therapy of early breast cancer include tamoxifen, anastrozole, letrozole, and exemestane. Other hormone therapy drug can be used for advanced breast cancer.

Hormone therapy should not be used during pregnancy because it can affect the fetus. It should be delayed until after the woman has given birth.

Targeted therapy

Drugs that target HER2, like trastuzumab (Herceptin^®), pertuzumab (Perjeta^®), ado-trastuzumab emtansine (Kadcyla^™) and lapatinib (Tykerb^®), are an important part of the treatment of HER2-positive breast cancers in women who aren’t pregnant. Trastuzumab is used as a part of adjuvant treatment after surgery, pertuzumab can be used with trastuzumab before surgery, and all of these drugs can be useful in treating advanced cancer. But based on animal studies and reports of women who were treated during pregnancy, none of these drugs are considered safe for the fetus if taken during pregnancy.

Everolimus (Afinitor^®) and bevacizumab (Avastin^®) are also targeted drugs that can be used to treat advanced breast cancer. Again, neither of these drugs is safe to use during pregnancy.

Breastfeeding during cancer treatment

Most doctors recommend that women who have just had babies and are about to be treated for breast cancer should stop (or not start) breastfeeding.

If surgery is planned, stopping breastfeeding will help reduce blood flow to the breasts and make them smaller. This can help with the operation. It also helps reduce the risk of infection in the breast and can help avoid having breast milk collect in biopsy or surgery areas.

Many chemo, hormone, and targeted therapy drugs can enter breast milk and be passed on to the baby. Breastfeeding isn’t recommended if the mother is getting chemo, hormone, or targeted therapy.

If you have questions, such as when it might be safe to start breastfeeding, be sure to talk with your health care team. If you plan to start back after you’ve stopped breastfeeding for a while, you will want to plan ahead. You may need extra help from breastfeeding experts.

Pulling all the treatment plans together

The hardest part of treatment is when there is a conflict between the best known treatment for the mother and the well-being of the fetus. If you are pregnant and have breast cancer, you may have hard choices to make—be sure you know all your options and get expert help. Your obstetrician will need to work with your surgeon, oncologist, radiation oncologist, and others involved in your care. A counselor or psychologist should also be part of your health care team, to help give you the emotional support you need.

If you would like more information on breast cancer and its treatment, please read our document called Breast Cancer.

Survival rates after breast cancer during pregnancy

Pregnancy can make it harder to find, diagnose, and treat breast cancer. Most studies have found that the outcomes among pregnant and non-pregnant women with breast cancer are about the same for cancers found at the same stage, but not all studies agree. A 2013 study looked at more than 300 women diagnosed during pregnancy. During the 5-year follow-up, researchers reported comparable survival in women at the same stage whose breast cancer was found when they weren’t pregnant. Disease-free survival tended to be slightly shorter in the pregnant women.

Some doctors believe that ending the pregnancy may help slow the course of more advanced breast cancers, and they may recommend that for some women with advanced breast cancer. It’s hard to do research in this area, and good, unbiased studies don’t exist. Ending the pregnancy makes treatment simpler, but older studies that looked at pregnant women have reportedly not found that ending the pregnancy improves a woman’s overall survival or cancer outcome. Of note, there were some flaws that could have biased the outcomes of these studies. For example, the women who had more advanced disease were more likely to end their pregnancies. More recent studies on this can’t be found in the available medical literature, and it’s hard to know if outcomes would be different with more modern treatments.

Studies have not shown that the treatment delays, sometimes needed during pregnancy, have an effect on breast cancer outcome either. But this, too, has proven to be a difficult area to study. Finally, there are no reports showing that breast cancer itself can harm the baby.

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Main Reference: http://www.cancer.org/cancer/breastcancer/moreinformation/pregnancy-and-breast-cancer