If you are diagnosed with breast cancer while pregnant, how far you are into your pregnancy (first, second or third trimester) will influence the use of diagnostic tools and the treatment you receive. Ultrasound on your breast will not hurt your unborn baby and shielding will be used to protect your abdomen during mammography. MRI is not usually recommended for women in the first trimester (conception to 12 weeks). The cancer itself will not affect your baby's development, nor their likelihood of cancer in later life.
The treatment you receive will depend on the type of breast cancer you have and the trimester of your pregnancy. Most women are able to undertake treatment while pregnant but some choose not to and such decisions should be undertaken in careful consultation with your partner (if you have one), your obstetrician and oncologist. If chemotherapy is advised during the first trimester (if the cancer is particularly aggressive and delaying treatment could endanger you), a termination may be discussed with you.
Treatment during pregnancy
The following is an overview only - all treatment decisions should be made in consultation with your specialist team. If you are nearing the end of your pregnancy, your team may decide to delay any treatment until after birth.
A sentinel node biopsy procedure is not usually recommended during pregnancy as the dye/radioactive tracer used in this procedure may harm your baby. However the procedure is sometimes carried out using much lower doses.
Breast cancer surgery to remove the tumour can be performed at any time during pregnancy. Due to the risk radiation treatment poses to your unborn child, a full mastectomy will most likely be recommended because a partial mastectomy (also known as a lumpectomy) would require follow up radiotherapy. However, if you're in the third trimester, breast conserving surgery may be performed. Breast reconstruction is an option for you too but due to the length of this operation and recovery time needed, it would be delayed until after birth.
Chemotherapy to destroy the cancer cells is possible during pregnancy but is not given during the first trimester as it could harm your baby. It is generally safe during the second and third trimesters. Chemotherapy is usually stopped 3 weeks prior to your due date to avoid complications at birth (eg there is a higher risk of infection for you) but can be continued after birth.
Radiotherapy is often given after chemotherapy, but would not commence until after birth (when chemotherapy is over). Radiotherapy is not recommended at any time during pregnancy as it poses a risk to your unborn baby, even low-dose. It may be possible to delay radiotherapy until after birth - your specialists will discuss this with you.
Hormone blocking therapies such as Tamoxifen are not given during pregnancy but can be taken after birth, if appropriate for your type of cancer. The targeted treatment Herceptin (for HER2 positive breast cancers) is not usually given during pregnancy but is fine after birth if appropriate for your type of cancer.
Delivering your baby
Most women diagnosed during pregnancy complete their full term and experience no difficulties at delivery. Caesarean section is avoided when possible as it carries a heightened risk of infection for you (especially if you have been having chemotherapy which affects the immune system).
You may find it hard to cope with caring for your new baby. You may still feel unwell, tired or 'out of sorts' after treatment. You may be unable to care for your baby as you would like to. Having chemotherapy after birth or starting radiotherapy present challenges also. Stopping breast feeding is advised before treatment commences. Breast feeding is not recommended during treatment for breast cancer as the drugs can pass through the bloodstream and into breast milk.
If you're experiencing difficulties, share how you're feeling with those close to you and ask for some practical support. Letting people know what you need is the first step. Your breast care nurse can help with some information and support options too.