Breast Cancer During Pregnancy: Diagnosis, Surgery and Treatment
Breast cancer during pregnancy can usually be safely diagnosed and treated without waiting until after the baby is born. Breast cancer surgery, including lumpectomy or mastectomy and sentinel lymph node biopsy, can be performed during pregnancy, while certain chemotherapy treatments can be safely given during the second and early third trimesters. The best treatment for breast cancer in pregnancy depends on the stage of the cancer, breast cancer subtype and how many weeks pregnant you are, and should be carefully coordinated between your breast cancer surgeon, oncologist and obstetric team.
Being diagnosed with breast cancer while pregnant can understandably create an immediate conflict in your mind: How do we treat the cancer without harming the baby?
Fortunately, treating the mother and protecting the pregnancy are not mutually exclusive. Many aspects of modern breast cancer treatment can safely proceed during pregnancy. Others — particularly radiotherapy, hormone therapy, HER2-targeted treatment and immunotherapy — usually need to wait until after delivery.
The key is therefore not simply whether breast cancer can be treated during pregnancy, but which treatments can be given safely at each stage of pregnancy and in what order.
As a specialist breast cancer and oncoplastic surgeon, I work closely with the other specialists involved in a woman's care to develop an individual treatment plan. You can read more about my approach to breast surgery and breast cancer care.
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What is pregnancy-associated breast cancer?
Pregnancy-associated breast cancer (PABC) generally refers to breast cancer diagnosed during pregnancy or within the first year after giving birth.
Pregnancy causes major changes within the breast. Breasts become larger, firmer and often more nodular as the milk-producing tissue develops. These normal changes can make a new breast lump more difficult to recognise and, importantly, can sometimes lead women to assume that a lump is simply part of pregnancy or breastfeeding.
A breast lump during pregnancy should still be investigated.
Most breast lumps occurring during pregnancy are not breast cancer. However, a new or persistent breast lump should not simply be attributed to pregnancy, particularly if it is firm, enlarging or otherwise concerning.
Pregnancy is not a reason to delay assessment of a breast lump.
Can I have breast imaging while pregnant?
Yes. Breast imaging can be safely performed during pregnancy when clinically indicated.
For a new breast lump, targeted breast ultrasound is particularly useful and does not involve radiation. Mammography can also be performed during pregnancy when required.
The important principle is that a potentially concerning breast symptom should be appropriately investigated rather than waiting until after delivery.
Can I have a breast biopsy during pregnancy?
Yes. A breast biopsy can be safely performed during pregnancy.
If imaging identifies a suspicious breast lesion, a core needle biopsy is generally used to obtain tissue for diagnosis. The biopsy tells us whether the lump is cancerous and, if breast cancer is identified, provides important information about the tumour.
This includes whether the cancer is:
oestrogen receptor (ER) positive
progesterone receptor (PR) positive
HER2 positive
triple-negative breast cancer
These results are particularly important during pregnancy because the safest treatment sequence differs between the various breast cancer subtypes.
Can breast cancer surgery be performed during pregnancy?
Yes. Breast cancer surgery can generally be safely performed during all three trimesters of pregnancy.
Surgery remains one of the main treatments for breast cancer during pregnancy. Depending on the cancer and the stage of pregnancy, this may involve either lumpectomy (breast-conserving surgery) or mastectomy, together with appropriate assessment of the lymph nodes under the arm.
Pregnancy does create additional considerations for anaesthesia, positioning during surgery and prevention of blood clots, particularly later in pregnancy. Breast cancer surgery during pregnancy should therefore be coordinated with the obstetric and anaesthetic teams.
Do I need a mastectomy if I am pregnant?
No. Being pregnant does not automatically mean that you need a mastectomy.
For suitable early breast cancers, lumpectomy or breast-conserving surgery may still be an option.
The main issue is not the lumpectomy itself. The difficulty is that lumpectomy is normally followed by breast radiotherapy, and radiotherapy is generally postponed until after the baby is born.
Therefore, the number of weeks remaining in the pregnancy becomes important.
For example, a woman diagnosed at 30 weeks of pregnancy has a relatively short interval before radiotherapy can commence after delivery. A woman diagnosed at six weeks would potentially have a much longer delay.
This is one of the reasons why the treatment of breast cancer during pregnancy needs to be individualised rather than applying the same operation to every woman.
Breast cancer treatment by trimester
One useful way of understanding breast cancer treatment during pregnancy is to divide treatment according to the trimester.
Breast cancer in the first trimester
The first trimester — up to approximately 13 weeks — is the most challenging period for breast cancer treatment because this is when the baby's organs are developing.
Chemotherapy is generally avoided during the first trimester.
Breast surgery, however, can still be performed.
For women diagnosed early in pregnancy who wish to continue their pregnancy, mastectomy may sometimes be recommended, particularly if lumpectomy would create an unacceptably long delay before radiotherapy could be given.
However, mastectomy is not an automatic requirement. Breast-conserving surgery may still be considered in carefully selected women, particularly later in the first trimester.
The decision depends on the cancer itself, its subtype, lymph node involvement and the anticipated timing of other treatments.
Breast cancer in the second trimester
The second trimester — approximately 14 to 27 weeks — provides considerably more flexibility for breast cancer treatment.
Both lumpectomy and mastectomy can be considered according to the usual cancer-related factors.
Importantly, certain chemotherapy regimens can also be administered during the second trimester when chemotherapy is required.
For some cancers, chemotherapy may be recommended before surgery. This is called neoadjuvant chemotherapy and may be particularly useful for:
larger breast cancers
cancers involving the lymph nodes
triple-negative breast cancer
cancers where reducing the tumour size may allow breast-conserving surgery.
Radiotherapy following lumpectomy is postponed until after delivery.
Breast cancer in the third trimester
Treatment during the early third trimester may be similar to treatment during the second trimester.
As delivery approaches, however, treatment planning changes.
Chemotherapy is generally avoided after approximately 35 weeks, as low blood counts around the time of delivery could increase the risk of infection or bleeding for the mother and baby.
When breast cancer is diagnosed very late in pregnancy, breast surgery may still proceed during pregnancy. Alternatively, where obstetrically appropriate and the baby has reached sufficient maturity, delivery and subsequent cancer treatment can sometimes be coordinated.
Can I have chemotherapy while pregnant?
Yes. Some breast cancer chemotherapy can be safely given during pregnancy, but the timing is extremely important.
Chemotherapy is generally avoided during the first trimester.
Certain commonly used breast cancer chemotherapy drugs, including anthracycline-based treatments and, in appropriate circumstances, taxanes, may be used during the second and early third trimesters.
Chemotherapy is generally stopped as delivery approaches.
However, chemotherapy is only one form of systemic breast cancer treatment. Several other modern treatments are usually postponed until after delivery, including:
hormone or endocrine therapy, such as tamoxifen
HER2-targeted therapy, such as trastuzumab
immunotherapy
radiotherapy
This is why knowing the breast cancer subtype is so important when planning treatment during pregnancy.
Does the type of breast cancer matter during pregnancy?
Yes. Breast cancer subtype can significantly change the treatment plan during pregnancy.
Breast cancer is not one disease. Treatment differs substantially between hormone receptor-positive, HER2-positive and triple-negative breast cancer.
HER2-positive breast cancer during pregnancy
HER2-positive breast cancer would normally be treated using HER2-targeted medications such as trastuzumab (Herceptin), usually in combination with chemotherapy.
HER2-targeted treatment is generally avoided during pregnancy because of potential harm to the developing baby, including significant reduction in amniotic fluid.
Depending on the trimester, chemotherapy may still be given during pregnancy, with HER2-targeted therapy commencing after delivery.
Triple-negative breast cancer during pregnancy
Triple-negative breast cancer (TNBC) does not express oestrogen receptors, progesterone receptors or HER2.
Systemic treatment is particularly important for many triple-negative breast cancers. When diagnosed during the second or early third trimester, chemotherapy can often be administered before surgery when appropriate.
Immunotherapy, which is now an important component of treatment for some triple-negative breast cancers outside pregnancy, is generally avoided during pregnancy.
Hormone receptor-positive breast cancer during pregnancy
Hormone receptor-positive breast cancers are cancers that express oestrogen receptors (ER) and/or progesterone receptors (PR).
Treatments such as tamoxifen form an important part of the long-term management of many of these cancers.
However, endocrine treatment is not used during pregnancy because of potential fetal harm and is therefore postponed until after delivery.
Surgery and, where indicated, chemotherapy can still form part of the treatment plan during pregnancy.
Can I have a sentinel lymph node biopsy while pregnant?
Yes. Sentinel lymph node biopsy can be performed during pregnancy using an appropriate technique.
Sentinel lymph node biopsy is commonly performed during breast cancer surgery to determine whether cancer has spread to the lymph nodes under the arm.
During pregnancy, sentinel node mapping can be performed using a small dose of technetium-99m radiocolloid.
Blue dyes normally used as an additional method of finding the sentinel lymph node are generally avoided during pregnancy.
The word radioactive understandably causes concern during pregnancy. However, the very small dose of radiocolloid used for sentinel lymph node mapping should not be confused with radiotherapy.
Can I have breast reconstruction during pregnancy?
Breast reconstruction may be possible during pregnancy, but simpler and staged approaches are generally preferred.
If mastectomy is required, an immediate tissue-expander reconstruction may be considered in carefully selected women.
However, pregnancy causes significant and continuing changes to breast volume and shape. Further changes occur following delivery, breastfeeding and eventually when lactation stops. These changes can make it difficult to predict the final breast shape and symmetry.
Complex reconstruction also means longer surgery and must never unnecessarily delay cancer treatment.
For these reasons, definitive breast reconstruction or more complex reconstructive procedures may be better delayed until after pregnancy and completion of the necessary cancer treatment.
Does breast cancer mean I need to terminate my pregnancy?
No. A diagnosis of breast cancer does not automatically mean that a pregnancy needs to be terminated.
Many women can undergo breast cancer surgery during pregnancy and, depending on gestational age, receive appropriate chemotherapy while continuing their pregnancy.
The first trimester presents the greatest challenge because chemotherapy and several other treatments cannot generally be given safely during this period.
Decisions around pregnancy therefore need to consider:
the stage and biology of the cancer, the number of weeks of pregnancy, which treatments are required and when they need to start, as well as the woman's own wishes and priorities.
These are highly individual decisions and should be made together with an experienced multidisciplinary team.
Will pregnancy make my breast cancer prognosis worse?
Pregnancy-associated breast cancers can sometimes be diagnosed at a more advanced stage, partly because normal pregnancy-related breast changes may make a cancer more difficult to recognise.
The important issue is therefore avoiding unnecessary delay in diagnosis and treatment.
A breast lump that persists during pregnancy or breastfeeding should not simply be watched for several months on the assumption that it is pregnancy-related.
With appropriate and timely treatment, many women diagnosed with breast cancer during pregnancy can be treated successfully.
Treating breast cancer while protecting the pregnancy
A diagnosis of breast cancer during pregnancy can initially make it feel as though there are two competing priorities: treating the cancer and protecting the baby.
In many situations, we can do both.
The key is carefully coordinating the timing of breast surgery, lymph node surgery, chemotherapy, delivery, radiotherapy and subsequent targeted or hormonal treatment.
There is therefore no single treatment pathway for “breast cancer during pregnancy”.
A woman who is seven weeks pregnant with a small ER-positive breast cancer faces very different decisions from someone who is 24 weeks pregnant with triple-negative breast cancer, or someone diagnosed with HER2-positive breast cancer at 36 weeks.
The stage of pregnancy matters. The stage and subtype of the breast cancer matter. Most importantly, the individual woman and her priorities matter.
For more information about breast cancer surgery, breast-conserving surgery, oncoplastic techniques, mastectomy and breast reconstruction, visit my Breast Surgery page.