Pregnancy-associated breast cancer
Pregnancy-associated breast cancer is breast cancer that is diagnosed during pregnancy, breastfeeding or in the first year post-delivery. It affects one in every 3000 pregnancies.
Most women are able to undergo treatment for breast cancer while pregnant, without harming their unborn baby. The cancer itself is not associated with a risk to the baby’s development. Termination of the pregnancy isn’t usually advised, as research has not shown termination to improve outcomes for women. However, if women have aggressive or advanced disease, or chemotherapy is required during the first trimester of pregnancy, termination may be discussed with the patient. This decision should follow a full discussion between the patient and their multidisciplinary team and obstetrician.
Diagnosing breast cancer in pregnancy
Pregnancy-associated breast cancer may be diagnosed at a later stage, due to changes in the breast during pregnancy and breastfeeding, which make cancer more difficult to detect. Pregnant women will undergo the triple test to confirm a diagnosis of breast cancer. Ultrasound is considered safe during pregnancy, although shielding will be used for the abdomen. MRI is not usually recommended for women in the first trimester.
Treatment during pregnancy
Treatment can start during pregnancy, however if the patient is close to their due date, it may be recommended for treatment to be delayed until after birth.
Surgery to excise the cancer can be performed at any stage during pregnancy. However, a full mastectomy will likely be recommended as radiation therapy is not advised during pregnancy (breast conserving surgery requires follow-up radiation therapy). Women in the third trimester of their pregnancy may be able to have breast conserving surgery, provided radiation therapy starts after the birth of their baby.
A sentinel node biopsy can be carried out during pregnancy, using a lower dose of the radiation tracer. Breast reconstruction is only offered as a delayed procedure in pregnant women, due to the length of the operation and recovery time required.
Chemotherapy is not given during the first trimester but is generally considered safe in the second and third trimesters. Treatment is stopped three weeks prior to the patient’s due date to avoid complications at birth (i.e. infection) but can be continued after birth.
Endocrine therapy is not recommended during pregnancy but may be taken after birth. Herceptin is used after birth, if needed.
Birth and post-birth
Most patients diagnosed during pregnancy are able to reach full-term and experience no additional complications at delivery. Where possible, Caesarean section is avoided as it carries a heightened risk of infection, particularly for those patients undergoing chemotherapy.
Women will be advised not to breastfeed during treatment, as treatments can pass through the bloodstream and into breastmilk. Patients should discuss the viability and safety of breastfeeding during treatment with their oncologist.
Patients may require extra support in caring for their newborn while undergoing cancer treatment. Patients should discuss eligibility for assistance with their medical team, and arrange practical support with friends and family.
