Breast cancer during pregnancy

Niru Anne, MD

Surgical Oncology

A breast cancer diagnosis is devastating at any time, but it’s especially frightening during pregnancy. What are the treatment options? Is it safe to have chemotherapy while pregnant? Breast surgeon Niru Anne, MD, explained what you need to know.

How common is breast cancer during pregnancy?

Breast cancer is the most common cancer during pregnancy, occurring in 1 in 3,000 women. Breast cancer during pregnancy is defined as any cancer in the breast that’s found during pregnancy or breastfeeding, or within one year of having a baby. The average age of onset when it comes to breast cancer in pregnancy is about 30 to 38.

Can pregnancy cause breast cancer?

Pregnancy itself does not cause breast cancer, but it can make it harder to detect the breast cancer.

“There are multiple changes that happen in the breasts during pregnancy and breastfeeding,” Dr. Anne said. “There’s a lot of glandular growth and changes in the ducts, so it can become quite difficult to detect a mass. Everything in the breast feels like a lump because the glands are so big. This leads to a delay in diagnosis. And because of this, the stage of the cancer we find during pregnancy may be much higher.”

Can breast cancer be treated during pregnancy?

“A diagnosis of breast cancer does not mean that treatment must be put off until the pregnancy is done,” Dr. Anne said. “It’s important to have timely treatment. There’s also no data that says terminating the pregnancy is going to improve the cancer outcomes. Pregnant women who get treated during their pregnancy for breast cancer do go on to have healthy babies and healthy lives after.”

How is breast cancer diagnosed during pregnancy?

If you notice a lump, mass or nipple discharge, the first step is to reach out to your OB/GYN who can perform a clinical breast exam.

The next step is a breast ultrasound, which is safe during pregnancy. With breast ultrasound, there is no concern for radiation exposure to mother or baby, and the test is very good at detecting a mass or a lump.

If the ultrasound detects a mass, a mammogram may be recommended. To prevent radiation exposure to mother and baby, a lead shield would be placed over the abdomen of the mother.

“Mammograms are very difficult to interpret so we try not to do a mammogram unless we must,” Dr. Anne said. Regardless of the mammogram’s results, a biopsy is needed.

“If someone feels a lump, we’ve got to do a biopsy regardless of what that mammogram shows or doesn’t show because there’s a potential for a misinterpretation of the mammogram,” Dr. Anne explained. “We could do a fine needle aspiration version, which means we take out some cells, or we could do a core needle biopsy, which involves taking out a little piece of the tissue.”

A test that is not typically used during pregnancy is MRI, because it uses a contrast agent that could pass the placenta barrier.

How is breast cancer treated during pregnancy?

Once cancer has been diagnosed, it’s important to have an accurate assessment of the cancer’s stage to determine the right course of treatment. Staging involves doing chest X-rays to check the lungs for disease. Again, the mother’s abdomen would be shielded during this procedure. An ultrasound can also be used to look at the liver and make sure there are no signs of the disease.

Bone scans and CT scans are typically avoided because radiation exposure is high. MRI, which is often used to check the spine, is also avoided unless necessary.

“If the cancer is found to be early stage, which is stages one and two, pregnant women are treated just like non-pregnant women, with a few modifications to maintain the baby’s safety,” Dr. Anne said. “Early-stage breast cancer, fortunately, is a very treatable condition whether the person is pregnant or not pregnant.”

Surgery is the preferred method of treatment because breast surgery can be done during pregnancy without harming the baby or the mother. “It’s best to do the surgery in the second or third trimester to avoid any potential effect from the anesthesia on the baby,” Dr. Anne said.

Certain types of chemotherapy can be offered during the second and third trimester, but radiation should only occur after the baby’s delivered.

For the most effective treatment, Dr. Anne said it’s important to have a multidisciplinary care team, which includes an OB/GYN, a medical oncologist, surgical oncologist, and radiation oncologist. It’s also important to have a maternal fetal medicine team and NICU support for the baby.

“About 10% of the babies born to mothers undergoing treatment for breast cancer need NICU support, so it’s very important to deliver in a hospital with perinatologists and maternal fetal medicine specialists,” Dr. Anne said.

What does breast cancer treatment look like if you’re breastfeeding?

Surgery and radiation can be performed without any impact to the breastmilk. However, chemotherapy agents can be passed to the baby through breastmilk. If you want to continue breastfeeding, your medical oncologist can discuss which chemotherapy options are safest.

How does breast cancer treatment during pregnancy affect the baby?

“There are case reports, both European and U.S. based, that looked at how chemotherapy affected delivery outcomes,” Dr. Anne said. “There’s some interesting data where they looked at whether there were any developmental delays in children born to mothers who had chemotherapy. The number of patients is small, but data showed 97% of the children had no developmental delays. It’s a small retrospective study that looked at follow up on children past elementary school and into middle school.”

The bottom line

When it comes to breast cancer during pregnancy, is it’s important to raise concerns early because a delayed diagnosis can lead to higher stage breast cancers.

Pay attention to how your breasts are changing and reach out to your OB/GYN if you have any concerns. “If it’s your first pregnancy and you’re unsure what your breast should feel like, just go and get evaluated,” Dr. Anne said.