The Importance of Understanding Breast Cancer in Pregnancy

Breast cancer is the most common invasive cancer diagnosed during pregnancy. ^{1 –4} It is, therefore, critical for care providers to carefully evaluate all pregnant women with new breast symptoms, to avoid a delay in diagnosis. The study by Rojas et al. ⁵ in this issue provides a very helpful review of the incidence, imaging findings, and treatment of pregnancy-associated breast cancer (PABC).

The importance of this work is well stated in the abstract, where it is pointed out that the incidence of PABC is increasing as more women choose to delay childbearing and as the incidence of breast cancer rises. ^1,4

This article defines PABC and the incidence, 20% of breast cancers in women aged 25–29 years, and indicates that outcomes can be equivalent to nonpregnant patients matched for age and stage. It is also noted that breast imagers must be aware that diagnosis and defining extent of disease are essential for rapid and appropriate treatment. Detection is frequently achieved by breast ultrasound, and mammography is considered safe, especially with abdominal shielding. Breast MRI is not used during pregnancy due to concerns regarding contrast agents containing gadolinium. ^1,6

Treatment is summarized in this review and the surgical team must be aware that both lumpectomy and mastectomy are feasible. Sentinel node guidance and procedures are appropriate and decrease the risk of surgical complications, similar to women who are not pregnant.

Chemotherapy can be safely used without impacting fetal outcomes in the second and third trimesters, which indicates that pregnancy can be continued while treatment is implemented. However, medical oncologists must be aware of the importance of the selection of safe and effective treatment regimes. There are several drugs that should be avoided and others are contraindicated. Radiation therapy must be delayed until postpartum for fetal safety.

As pregnancy changes blood volume as well as physiology, drug clearance through liver and kidneys may be altered. Yet at this time, no changes in treatment intervals or dose are currently recommended. Monitoring of blood counts and toxic effects should be more frequent as this can be impacted.

Pregnancy can mean that requirements for supportive therapy are greater as side effects such as dizziness, nausea, and vomiting may be accentuated. There are many considerations for maternal and fetal health that must be considered and this is best done with a team approach with oncology and obstetrical experts. At the time of delivery, vaginal delivery is preferred for maternal health if this is possible as this results in fewer complications.

After delivery a unique set of challenges arise requiring a knowledgeable and available multidisciplinary team. This must address maternal and neonatal needs, importantly, cytopenia issues in both mother and fetus. If delivery results in a premature fetus, appropriate care and expertise must be available.

This informative review raises several important points. Pregnant women should be educated regarding the expected changes in their breasts during pregnancy and the importance of reporting symptoms to their providers in a timely manner. The most common presentation of PABC is a palpable mass. ^1,4 Patient and provider awareness regarding normal physiological breast changes during pregnancy versus more worrisome lumps can mean the difference between early and late detection. Thus, providers should be familiar with symptoms of breast cancer, and refer their pregnant patients for breast imaging when there is a question of a suspicious clinical finding. Radiologists must be aware of the appropriate evaluation of breast symptoms in pregnant women, including the expected breast changes on imaging. ^6,7 A multidisciplinary oncology team approach to treatment is required. Although there is still debate regarding outcomes, ^8,9 this review reports that timely detection, diagnosis, and treatment can lead to survival for PABC being equivalent to breast cancers in nonpregnant women.