Young Women Diagnosed With Breast Cancer After Childbirth Face Higher Risk of Metastasis

A recent study that found that women under age 45 diagnosed with early-stage breast cancer within 10 years of giving birth were at higher risk of the cancer coming back as metastatic than young women with early-stage breast cancer who never gave birth. The study was published in JAMA Network Open.

Background

Past research showed that young women diagnosed with early-stage breast cancer within 5 years of their last birth had a higher risk of developing metastatic breast cancer than young women with early-stage breast cancer who never gave birth. Metastatic breast cancer, also called stage IV breast cancer, means that the cancer has spread beyond the breast to other parts of the body, such as the bones, liver, lungs, or brain.

Researchers believe that this higher risk of developing metastatic breast cancer is caused by changes in breast tissue that happen after a baby is born. They think these changes may make it easier for cancer cells to use lymph nodes to spread from breast tissue to other parts of the body.

The purpose of this study was to understand if the increased risk of cancer coming back continued for women diagnosed more than 5 years after a young woman’s last birth.

Design

This study followed 701 participants from the Colorado Young Women’s Breast Cancer Cohort who were 45 years or younger when they were diagnosed and had been treated for stage I to III breast cancer. Researchers placed the women who had given birth into groups based on how long after their last childbirth they were diagnosed

• within 5 years
• between 5 and 10 years
• 10 years or more

Participants who had never given birth were placed in a separate group.

Results

The study found that women who gave birth in the last 10 years were more likely to have a metastatic breast cancer recurrence than their peers who never gave birth. Those diagnosed with stage I or stage II breast cancer who gave birth in the last 10 years had a risk of breast cancer travelling to other parts of the body 3.5 to 5.0 times as high as participants who never gave birth.

Participants diagnosed with breast cancer 10 or more years after their last childbirth still had a higher risk of developing metastatic breast cancer compared to those who had never given birth. But they had a significantly lower risk than women diagnosed less than 10 years after the last time they gave birth.

The researchers also found that participants diagnosed within 5 years of their last birth were more likely to have cancer spread to their lymph nodes.

The study had limitations: the participants were primarily from Colorado, non-Hispanic white, lean, and less likely to die from breast cancer than researchers would expect. The results may have been different with a more diverse group of women.

What This Means for You

About 45 percent of the young women diagnosed with breast cancer in this study were within 10 years of their last birth. The researchers say this means that nearly half of all young women with early-stage breast cancer may have an increased risk of metastatic breast cancer recurrence.

If you have been diagnosed with early-stage breast cancer and have recently given birth, talk to your healthcare provider about this study. Recent childbirth could raise the risk of breast cancer traveling to other parts of your body. Ask your healthcare provider about factors that could decrease or increase your risk of breast cancer returning or spreading and what he or she recommends.

Goddard ET, Bassale S, Schedin T, et al. Association between postpartum breast cancer diagnosis and metastasis and the clinical features underlying risk. JAMA Netw Open. 2019;2(1):e186997. doi:10.1001/jamanetworkopen.2018.6997