Dr. Chino talks with Dr. Erin Roesch and patient advocate Julia Maues about pregnancy associated cancer with a focus on breast cancer, the most common cancer diagnosed during pregnancy. This discussion is based off an JCO OP review article published in late 2024 called "Multidisciplinary Management of Pregnancy-Associated Breast Cancer."

Transcript

Dr. Fumiko Chino:
Hello and welcome to Put Into Practice, the podcast for the JCO Oncology Practice. I'm Dr. Fumiko Chino, an assistant professor in radiation oncology at MD Anderson Cancer Center with a research focus on access, affordability, and equity.

The incidence of early-onset cancer—new cancers in adults under the age of 50—is rising by 1% to 2% annually. Young women appear to be at particular risk, with cancer incident rates over 80% higher than similarly aged male counterparts. Collectively, that means that more patients are being diagnosed with cancer during their childbearing years. Pregnancy-associated cancer occurs in 1 in every 1,000 to 3,000 pregnancies and refers to cancer that is diagnosed either during pregnancy or within 1 year of delivery.

On today's episode, we'll be talking about pregnancy-associated cancer, with a focus on breast cancer, as it is the most common cancer diagnosed during pregnancy. This discussion will be based off of a JCO OP article published in late 2024 called "Multidisciplinary Management of Pregnancy-Associated Breast Cancer."

I'm excited to welcome both the first author of this review article and a patient advocate to the podcast today. They are both passionate about improving outcomes for people with breast cancer.

Dr. Erin Roesch is an assistant professor of medicine at Cleveland Clinic Lerner College of Medicine and a medical oncologist at the Cleveland Clinic Taussig Cancer Institute specializing in the treatment of breast cancer. She is involved in clinical trials research, and some of her specific interests include the care of young women diagnosed with breast cancer, fertility in oncology patients, and women's health and survivorship.

Julia Maues is a patient advocate working with researchers, clinicians, and other stakeholders to ensure research is patient-centered, innovative, accessible, and inclusive. She was working as an economist when she was diagnosed with breast cancer while pregnant in 2013. After delivering her son, she found out that cancer had already spread to her bones, liver, and brain. Julia co-founded GRASP (Guiding Researchers and Advocates to Scientific Partnerships), an organization that connects and fosters collaborations between researchers and patient advocates. She is also active within the Metastatic Breast Cancer Alliance and helped write the ASCO guideline for brain metastasis.

Our full disclosures are available in the transcript of this episode, and we've already all agreed to go by our first names for the podcast today.

Erin and Julia, it's really wonderful to speak to you today.

Dr. Erin Roesch:
Thank you. I appreciate the opportunity to be here and discuss this really important topic.

Julia Maues:
Thank you for having me. It's very important to include the patient voice on this topic, and unfortunately, I have a personal experience with this.

Dr. Fumiko Chino:
Our topic today is pregnancy-associated cancer. Erin, can you give us a quick overview of the background for pregnancy and breast cancer? I know in the recent era, breast cancer rates for those under the age of 50 have been rising faster than for other cancers, up to 1.4% per year since the mid-2000s. I'd always thought that pregnancy-associated cancer was pretty rare, and so I was really shocked to read in your paper that for women younger than 35, 1 in 6 with breast cancer are diagnosed around pregnancy.

Dr. Erin Roesch:
Yes. So, a cancer diagnosis during pregnancy is rare, with the incidence, as mentioned, of about 1 in 3,000 pregnancies, with pregnancy-associated breast cancer, or PABC, representing about 7% of all breast cancers diagnosed per year. Among women under the age of 45, PABC accounts for roughly about 2.5% to just over 6% of breast cancer cases. And for women less than 35 years, this rises to about 15.5%.

Studies have shown a rise in PABC in recent years, and this is anticipated to continue with the trend of delayed age at childbearing. In regards to the pathophysiology of pregnancy-associated breast cancer, various hypotheses have been proposed to kind of try and shed more light on how this occurs and the driving factors for PABC. So these include hormonal changes that occur during pregnancy and lactation, immunologic changes that can lead to the immune tolerance of tumor cells, and also breast tissue involution that occurs after delivery and breastfeeding, which can lead to a proinflammatory state.

In regards to risk factors, these include a positive family history, which is one of the strongest risk factors for breast cancer development, this includes pregnancy-associated breast cancer, pathogenic germline mutations—specifically BRCA1 or 2—and older maternal age at time of birth. We also know that breastfeeding has been shown to have a protective effect against breast cancer development.

Dr. Fumiko Chino:
So what I'm hearing from you is that just given the incidence rising in younger people and also delayed pregnancy, that this is really something that we're unfortunately going to be facing more and more frequently in our clinics and something that patients unfortunately will find that they have to face as well.

Dr. Erin Roesch:
Yes, yes, I think that's accurate. And just again, I think points to the importance of awareness of this particular topic.

Dr. Fumiko Chino:
Now, Julia, your lived experience in this space is really invaluable. Do you mind sharing it with us?

Julia Maues:
Yeah, of course. I was pregnant at 29, and I found a lump in my breast. I had an excellent OB-GYN and team, and the