Breast Cancer and Pregnancy: What You Need to Know

Written by: Beth Dougherty
Medically Reviewed By: Ann Partridge, MD, MPH; Filipa Lynce, MD; and Erica Mayer, MD, MPH

Key Takeaways 

  • While rare, breast cancer can develop during pregnancy. 
  • Most changes in the body are not a result of cancer, but anything out of the ordinary should still be examined by a healthcare provider. 
  • Even during pregnancy, there are almost always treatment options available to you that are effective and safe for you and your child. 
  • After treatment for early-stage, hormone-receptor-positive breast cancer, there is a safe way to temporarily pause endocrine therapy to pursue pregnancy. 

During pregnancy, a person’s body undergoes countless changes, including in the breasts. While changes in your body during this time are completely normal, it is still important to be aware of your own health and what is normal for you — even though anything unusual that is discovered will usually not be cancer. 

While rare, breast cancer can occur during pregnancy. Oftentimes, it can be difficult to separate a cancerous mass or lump, or another common sign of breast cancer, from what is a normal part of pregnancy. Ultimately, if you notice any changes to your body or anything unusual, it is important to report it to your health care provider.  

“If you find something that’s worrisome, make sure to have it professionally evaluated, and don’t be afraid to seek a second opinion,” says Ann Partridge, MD, MPH, co-founder and director of the Young and Strong Program for Young Adults with Breast Cancer at the Susan F. Smith Center for Women’s Cancers at Dana-Farber. “Research is constantly evolving, and it’s important for patients to get medically accurate information.” 

One new area of research is investigating the safety of pursuing pregnancy after breast cancer. If you are trying to balance the desire to have the best therapy possible with the desire to have a child, the POSITIVE clinical trial results suggest a way forward. For people who have been treated for early-stage hormone-receptor-positive breast cancer and who are taking hormone therapy to prevent recurrence, taking break from hormone therapy to have a baby did not increase risk of recurrence in the short-term. 

“We are still investigating the long-term risk, but this is encouraging for people who really want to have a baby,” says Partridge.   

Signs and symptoms of breast cancer 

The symptoms of breast cancer do not change if you are pregnant. However, they may be overlooked more often or dismissed as a result of the pregnancy, so it is important to be aware of them. 

The most common symptom of breast cancer is a new mass or lump, though most lumps are not breast cancer. Cancerous lumps do not all feel the same but tend to be irregular in shape and may feel firm or solid. These lumps can vary in size, and whether you can feel it may depend on where the lump is located in the breast, how big the breast is, and how deep the lump is positioned within the breast. 

Ultimately, it is impossible to diagnose a breast lump just by touch, so it is important for you to speak with your doctor if you notice any changes in your breasts

Other common signs and symptoms that may indicate breast cancer include: 

  • Mass or lump 
  • Dimpling of the skin or nipple (also referred to as peau d’orange) 
  • Asymmetry or one side feeling/looking more swollen 
  • Hard, round bumps in armpits 
  • Redness or flaky skin in the nipple or breast area 
  • Skin that is warm to touch 
  • Nipple discharge other than breast milk 
  • Pain 
  • Nipple turning inward (retraction) 

Even if you are experiencing one or more of the symptoms above, it does not mean you have cancer. For women who are pregnant, this is especially true, as common symptoms of breast cancer often overlap with benign causes. 

This is one of the reasons why it is important to have open communication with your health care provider and report any changes to your body.   

[Learn more about the signs of breast cancer.] 

Inflammatory breast cancer  

Inflammatory breast cancer (IBC) is a very rare and aggressive disease in which cancer cells block the lymph vessels (thin tubes that carry fluids and white blood cells through the lymphatic system) in the skin of the breast. IBC gets its name because it often causes the breast to appear red or inflamed. 

Someone with IBC will usually be able to pinpoint the exact moment they noticed a change in their breast. Symptoms typically present over a 24-hour period, and this form of breast cancer can often be detected without a lump. Common symptoms of IBC include: 

  • Redness of the breast 
  • Rapid swelling or enlargement of the breast 
  • Pain or itchiness of the breast 
  • Thickening of the skin on the breast and ridged or dimpled skin texture (peau d’orange) 
  • Swelling of the lymph nodes in your armpit or above/below the collarbone 

For patients who are pregnant or breast feeding, IBC is often originally misdiagnosed as mastitis: an inflammation of the breast due to an infection. Mastitis, which most frequently occurs in women who are breast feeding, is treated with antibiotics and typically resolves within a week of starting medication. 

If after a week your symptoms do not improve, it is important for patients and healthcare providers to follow up and seek a specialist. Persistent symptoms do not necessarily mean you have IBC, but they should be examined by a trained specialist. 

“If worrisome changes in the breast don’t improve with antibiotics, don’t be afraid to be your own advocate,” explains Filipa Lynce, MD, director of the Inflammatory Breast Cancer Program at the Susan F. Smith Center. “While incredibly rare, IBC can develop in pregnant women, and catching it early may lead to more effective treatment.” 

Treatment during pregnancy 

A breast cancer diagnosis can be a difficult and life-altering discovery. For patients who are also pregnant, the news can be incredibly overwhelming. 

However, if you are diagnosed with breast cancer while pregnant, there will almost always be treatment options available to you. Furthermore, there is no evidence that breast cancer itself can harm a developing baby. 

Most women diagnosed with breast cancer can still undergo many routine parts of breast cancer therapy including surgery. Likewise, if necessary, some chemotherapy regimens are considered generally safe in the second and third trimester of pregnancy. Chemotherapy can also lower the mother’s blood cell counts, so it is recommended to stop chemotherapy when nearing the time of delivery. 

Other therapies used in breast cancer treatment, such as radiation therapy, hormone therapy, targeted therapy, as well as the vast majority of clinical trials, must be held off until after delivery. 

A breast cancer diagnosis during pregnancy may lead to delicate conversations with your oncologist, and it is important to be honest and open so that you can come to the best decision for you and your child. 

“Regardless of your situation, there are almost always safe and effective treatments for breast cancer care in pregnancy,” says Erica Mayer, MD, MPH, director in the Breast Oncology Program at the Susan F. Smith Center. “It is important for a woman and her doctor to discuss all of the aspects of cancer care in pregnancy. 

“Small compromises may be necessary as a treatment plan is formulated; however, the overall plan will be directed towards a goal of providing effective and modern cancer care while protecting the developing baby.” 

Pregnancy after breast cancer 

Young adults with breast cancer often desire to have a biological child but question the safety of pursuing pregnancy after breast cancer.  

However, people who were diagnosed with early-stage, hormone-receptor-positive breast cancer are often prescribed hormone therapies, such as tamoxifen, aromatase inhibitors, and ovarian suppression medication, for 5 – 10 years after treatment to prevent recurrence. These drugs, also called endocrine therapy, can make pregnancy impossible or dangerous. Yet delaying pregnancy for 5 – 10 years can make it difficult for patients to conceive since fertility naturally decreases over time. 

A recent clinical trial, called POSITIVE and led by Partridge, investigated the safety of taking a break from hormone therapy for this patient group. The results show that pausing hormone therapy for two years to attempt conception, deliver a baby, and breast feed does not increase the risk of breast cancer recurrence in the short term.  

The study followed 500 premenopausal women aged 42 or younger diagnosed with stage I or stage II hormone-receptor-positive breast cancer. 

Patients followed this protocol: 

  • They stayed on hormone therapy for 18 – 30 months prior to taking a break to ensure patients benefit from some risk reduction. 
  • They stopped hormone therapy for a mandatory three months prior to conception to ensure the drugs are “washed out” of the body, as these medicines can cause birth defects. 
  • They resumed hormone therapy after pursuing pregnancy to keep the risk of recurrence low.  

Of those followed, 8.9% had breast cancer recurrence compared to 9.9% of similar patients in a separate cohort who did not pause hormone therapy. Rates of conception and childbirth were on par with or higher than rates in the general public. 

A subset analysis within POSITIVE compared women who became pregnant to those who did not. It confirmed previous retrospective data that pregnancy itself and the associated hormones don’t appear to increase risk of relapse in this population. 

“Those who paused hormone therapy to become pregnant did just as well as those who did not temporarily interrupt hormone treatment,” says Partridge. “At least in the short term, it is safe for the population we studied to become pregnant after a breast cancer diagnosis.” 

The study is ongoing so that the researchers can confirm long-term safety.  

If you have any questions regarding your specific situation, please bring them to your healthcare provider.