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AACR 2023: Special Symposium on Pregnancy and Breast Cancer

By BCRF | May 19, 2023

BCRF dives into this complicated diagnosis and what current research shows

Pregnancy is an exciting time in a woman’s life but may also be a time of great stress and worry about pregnancy complications, parenting, birth, finances, and more. For one in 3,000 pregnant women, they’ll face a shocking and devastating reality: a breast cancer diagnosis.

At this year’s American Association of Cancer Research (AACR) Annual Meeting, the presidential address, one of the conference’s most prominent events, was focused on this important issue. BCRF investigator Dr. Ann Partridge—a pioneering researcher on this topic who also recently presented and published major findings from a BCRF-supported study on pregnancy after breast cancer—chaired this insightful and moving symposium.

The panel was especially timely for several reasons: Breast cancer is the most common cancer found during pregnancy because it is also, unfortunately, one of the most common cancers in younger women. Breast cancer in pregnant women is increasing—likely due to a combination of more early-onset cancers being diagnosed and first-time mothers delaying pregnancy until later ages. State-by-state changes in reproductive healthcare are also significantly complicating options for these patients now and in the future. 

Here, we discuss this complex diagnosis and issues pregnant women with breast cancer face that were covered in this important session.

Diagnosing breast cancer during pregnancy

Breast cancer can be detected throughout a person’s pregnancy, but it can be more complicated to screen for and diagnose because of pregnancy itself: A lump may be interpreted as a normal change in the breast tissue due to the pregnancy and standard-of-care mammography is not recommended during pregnancy. Nevertheless, the majority of these breast cancers are found in the first trimester.

During pregnancy, health care providers routinely conduct a series of prenatal tests to assess how the fetus is developing. Depending on the mother’s age, high-risk status, and other factors, a doctor may recommend screening to look for any chromosomal abnormalities, and more and more, doctors are using a noninvasive test that examines cell-free DNA (cfDNA).

Researchers have discovered that cells release fragments of DNA into circulating blood (what’s called cfDNA). In a pregnant woman, the baby’s cfDNA circulates in her bloodstream as well, so doctors can examine fetal cfDNA for conditions like Down Syndrome with a blood draw as early as nine weeks.   

Researchers noted in the AACR symposium that in some cases cfDNA testing can reveal cancer in pregnant women. Just like normal cells, tumor cells release fragments of DNA into the blood that may be discovered incidentally while analyzing fetal cfDNA. While a pregnant woman may appear asymptomatic, this circulating tumor DNA indicates that a tumor is present and further tests are used to confirm. The person’s health care team must then work to gauge whether immediate treatment is needed or if it can wait until later in the pregnancy or postpartum.

Weighing risks and treatment challenges

The prognoses for pregnant women with breast cancer are similar to non-pregnant women, but treatment decisions are more complicated. Many considerations enter the picture as doctors strive to develop a treatment plan that benefits the woman without harming her baby.

Providers must consider if the fetus is at risk from the woman’s illness, if there are short- and long-term risks from treatment to both mother and fetus (toxicities), and whether the breast cancer could end the pregnancy itself. These complicated questions must all be considered as part of the decision-making process to provide the best breast cancer treatment.  

Investigators during this session were quick to note that the fetus’ wellbeing is closely tied to the pregnant woman’s wellbeing. This is top of mind for her and her cancer care team as they work together to make decisions and balance maternal and fetal wellbeing.

How breast cancer is treated during pregnancy

As AACR panelists shared, there is a lack of clinical trial data informing how pregnancy-related breast cancer is treated, in part due to the small number of possible participants and the difficulty of ethically randomizing them for such a study. This means that there is very little data to support the safety and efficacy of using standard-of-care treatments for these patients; but, thanks to research, investigators have made some gains to inform care.

Surgery is generally considered safe during pregnancy, but radiation, hormone therapies, and targeted therapies such as CDK4/6 inhibitors and trastuzumab (Herceptin®; used to treat HER2-positive breast cancer) are not recommended because they can affect fetal growth and development. Retrospective studies correlating different types of chemotherapies given during pregnancy with maternal and fetal outcomes (such as preterm birth, newborn size, congenital malformations, and other considerations) have provided clinicians with data showing that they are typically safe after the first trimester.

Generally, doctors start with a diagnostic workup to determine the characteristics of the individual’s breast cancer, including hormone receptor and HER2 status and stage of the disease. As in non-pregnant women, a treatment strategy is developed based on these factors.

However, in pregnant women, the timing of treatment is more critical and is highly dependent on the stage of the pregnancy. For instance, surgery can be performed to remove the tumor at all stages of pregnancy, but certain chemotherapies should only be given at later stages. The timing of birth is also considered: For some women, doctors recommend they be induced and deliver early to start certain treatments for their breast cancer.

Special care considerations for pregnant women with breast cancer  

Although rare, a woman’s situation may become more precarious if continuing a pregnancy jeopardizes her breast cancer prognosis, her health, or the health of the fetus.

At AACR, Dr. Virginia F. Borges of the University of Colorado spoke poignantly about patient anxieties in these situations as they try to make incredibly heavy decisions about continuing pregnancy. Dr. Borges stressed the need to support pregnant women with breast cancer so that they can make the right personal choices for themselves with support from their medical team and family.

Speaking from the patient perspective, advocate Julia Maues spoke about her personal experience with breast cancer during pregnancy years prior. Emotional at times, Maues echoed Dr. Borges and stressed how instrumental her care teams were to her prognosis and son’s health. She also reiterated how her teams’ sensitivity helped her navigate all her options to make the best personal and medical decisions possible.     

The importance of further research

Each breast cancer journey is different. As pregnant women with breast cancer navigate a diagnosis, they amass a healthcare team of oncologists, maternal-fetal medicine and neonatal health specialists, and psychosocial professionals who all use knowledge gained from current and past research to best treat each individual’s breast cancer. Research has given pregnant women with breast cancer hope that they can be successfully treated and carry to term.

“We need to engage multidisciplinary teams, utilize external resources, and contribute to registries and research so that we can learn more from the [patient] experiences that are happening now,” Dr. Partridge said.